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Evaluating Self-Unlocking Doors in Rollover Accidents using a Shock Testing Machine | Automotive manufacturers often rely upon features such as automatic locking to enhance the security and crashworthiness of doors in rollover accidents. This can be verified in warnings conveyed to vehicle owners through some owner's manuals. At the present time, there are no requirements on the dynamic performance of door locking systems within the Federal Motor Vehicle Safety Standards (FMVSS), although some static inertia requirements exist for latch systems. Field accident investigation and laboratory testing has revealed that some locked doors can self-unlock in rollover accidents when a vehicle sustains a roof impact. Using standard laboratory shock testing machinery, the acceleration boundaries required to trigger self-unlocking have been mapped for some sample doors. Impact pulses of surprisingly low levels of acceleration, when combined with sufficient duration have been found to trigger this response. Furthermore, two entirely different failure mechanisms have been identified and documented thus far. One failure mode results directly from inertial triggering of the locking system; this mode is anticipated by FMVSS. The second failure mode is the unexpected consequence of the vibratory response of the lock system linkage. This failure mode has not yet been recognized in the safety literature. This paper presents the findings of a field accident investigation where self-unlocking was believed to have occurred as well as test data from doors exhibiting the two different self-unlocking mechanisms. |
Investigation of Crash Impact Induced Oscillatory Response of Elements of Automotive Latch Systems | Vehicle door closure systems often include self-balancing double pendulum mechanisms. For example, the counterweight in the outside handle assembly is used to reduce handle motion under inertia loadings occurring during crash events. The system is configured in such a way that the inertia forces developed during a crash are applying opposite moments to each of the pendulums (i.e., to the handle and the counterweight). Investigation of crash impact induced oscillatory response of such mechanisms is presented in this paper. A comprehensive dynamic model is developed that captures all essential characteristics of the double pendulum mechanism. An important aspect of the model is its discontinuous nature due to potential impacts between both pendulums and between one of the pendulums and the base part. Analytical conditions of self-balancing of the double pendulum system are formulated and used to provide an insight into the principles of self balancing. During dynamic simulations of the system, high frequency / high acceleration amplitude oscillatory motion of the base part provides inertia input to the system. It is shown that the double pendulum systems usually respond to such excitation with irregular motion. A methodology has been developed to study this system behavior and to analyze the resulting motion of the system. The multi-level analysis presented in the paper is used to investigate the conditions under which the system may not respond to external excitations, and to quantify the irregular response of the system when it does. The sensitivity of the solutions of the dynamic model to variation of system parameters and input characteristics is also addressed in the paper. |
Testing and Modeling of Elevator Door Retention During Hallway Applied Lateral Loads | Most do not consider there to be a risk in pushing on, bumping into or falling against an elevator door from the hallway side. However, the lack of the elevator cars presence alone, and the potential for severe injury or even death make this seemingly mundane situation potentially critical. Standards exist relative to such situations, and past and current designs attempt to account for this possibility, still people get injured interacting with these doors every year. In order to evaluate a real-world elevator door system's ability to withstand the quasi-static and impactive loads that can be placed on it by the general public during its life, both intentionally and unintentionally, a predictive tool is needed. This work represents the combination of empirical laboratory testing and numerical modeling of a typical elevator door system exposed to quasi-static and dynamic loading. The test procedures and methodology employed in this work provided repeatable and reliable results in quasi-static and dynamic testing. Numerical simulation using MADYMO established a robust and accurate quasi-static model of a primary door failure mode. The quasi-static MADYMO model can be used for quasi-static loading at any height of load application on the door and at any gib engagement depth up to full engagement with reliable and repeatable results. The dynamic MADYMO model showed accuracy at the 3 mm (0.12 in.) gib engagement depth at any contact height and any contact speed. A preliminary 6 mm (0.24 in.) gib engagement depth dynamic model has been verified for full-mass impacts of up to 1.5 m/s (4.8 ft/s). |
DRE NVH Contribution Analysis of Vehicle Cavity Fillers - NVH Target Setting Process | The goal of this study is to measure the Noise, Vibration and Harshness (NVH) performance of passenger vehicle cavities under different drive conditions. Until now, little attention has been given to the impact of NVH performance of cavity fillers with respect to the driver's perception. To further understand this phenomenon, a four door sedan was instrumented with several microphones placed within different vehicle cavities. After instrumentation, the vehicle was tested under various road conditions; cruise, idle, street run, rough road and wide open throttle. The resulting data shows that there is a substantial noise presence in the hinge pillar and lower rocker cavities for all test conditions. The data also provides a means to rank the importance of the sound contribution of each vehicle cavities with respect to other cavities. To understand the NVH contribution of individual cavities to the driver's perception, the vehicle was placed inside a semi-anechoic chamber. The goal was to compute the transfer function of each cavity with respect to the driver's ear (DRE). The individual transfer functions could have been calculated by placing the random noise generator within each cavity while measuring the response at the DRE. This technique would have required several iterations of moving the noise generator from cavity to cavity. However, using the reciprocity concept, the noise generator can be placed at the DRE and the responses at all cavities can be measured simultaneously. Finally, having the road data along with all transfer functions, the relative importance of each cavity was determined with respect to the driver's ear. This methodology would enable vehicle manufacturers to understand the importance of cavity fillers to the vehicle's overall NVH performance. This technique would also help to optimize the application and provides NVH target setting goals for the vehicle cavity fillers. |
Numerical Investigation of the Transmission Loss of Seals and Slits for Airborne SEA Predictions | Seals and slits are often an important transmission path for vehicle interior noise at mid and high frequencies, and they are therefore often included in system level SEA models of interior noise. The transmission loss of seals and slits in such models is typically either measured experimentally or predicted using simple analytical models. The problem with the former is that it is expensive to investigate different design options using test; the problem with the latter is that simple analytical models often do not contain enough detail. The objective of this paper is therefore to investigate how much detail is needed in order to predict the transmission loss of typical slits and seals. Typical door seals are not directly exposed to exterior and interior sound fields, but instead are inserted in complicated “channel” sections formed by the door and pillar or rail structures. This study is therefore divided in two parts. The first part focuses on the effect of the channel (a “slit” type aperture between two acoustic spaces). The acoustic performance of various slits is investigated using fast 3D numerical models based on the Hybrid FE-SEA method. The use of this method makes it possible to diagnose the parameters controlling the transmission loss of a slit or seal across a broader frequency range than is possible with standard numerical methods such as BEM. The second part of the paper focuses on the transmission loss of the seal itself (with and without the presence of the channel). The sensitivity of the transmission loss to the deformation of the seal is also investigated (the deformation of the seal is predicted using a full non-linear deformation/contact analysis). |
Practical Application of Six Sigma with a Focus on Transmitted Variation – A Door Check Arm Opening Effort Case Study | This paper presents an approach for Six Sigma strategies to reduce the occurrence of failure mechanisms. In general terms, there are two ways to reduce the failures: a) shifting or tuning - DMAIC approach or b) shrinking - DCOV approach. When shifting or tuning, we move the mean output away from the failure mode boundary and when shrinking, we reduce the variability of the output. Also, the paper illustrates with a case study - Cargo truck door opening effort check arm - where demand and capacity distributions had its distance to failure mode increased leading to high-quality low-cost alternative in vendor tooling. |
Simulation of Outer Door Handle and Latch Responses in Side Impact using Component Test Methodology | A dynamic component test methodology using a door sub-system was developed to simulate the outside door handle/latch responses (accelerations and deformations) as in a full-vehicle NHTSA FMVSS 214 side impact test. The test methodology consists of a door sub-system (with door inner components) which is allowed to pivot by means of a hinge at the top of the door. The lateral structural load path affecting the door/rocker response was accounted and simulated (obtained from full-vehicle FE analysis) in this methodology by means of an energy absorbing material (Aluminum honeycomb) of predetermined stiffness. A bullet sled simulating the Moving Deformable Barrier (MDB) surface and stiffness at the same relative location to the door/rocker (as in full-vehicle test) strikes the stationary hinged door at an initial velocity of approx. 30 mph (longitudinal component of crab cart velocity of 33.5 mph). Upon impact, the door sub-system rotates about the hinge simulating both the acceleration at the outer handle and latch, and overall deformation of the door. The front door responses (acceleration and velocity) near outer handle and latch from the component test methodology are compared to full-vehicle for validation. |
Development of Door Module Plate with Long-fiber-reinforced Thermoplastic Polypropylene | These days, many new applications for long-fiber-reinforced thermoplastic Polypropylene (PP-LFT) have been coming in the worldwide automobile market. Main issue of this paper is to explain how PP-LFT door module plate was developed, which processes were executed, and what kind of advantages we can get, once it is used as door module plate. Some of steel parts in the car have been changed to the reinforced PP-LFT with weight-saving. Change of material can make modularity more efficient, and then improvement of manufacturing process results in cost-saving. Stress analyses and MoldFlow analyses have been performed to choose the optimized conditions and a product model. Then various tests including waterproof test, drop-weight test and stiffness test have been executed to check if the weight-reduction is suitable for mass-production. PP-LFT door module plates including 40% glass-fiber were used in this paper using above mentioned methods, and, as a result, it is proved to get 21.5% weight reduction of plate and 12% reduction of door module assembly versus conventional steel module plates. |
CAE Virtual Door Slam Test for Plastic Trim Components | Visteon has developed a CAE procedure to qualify plastic door trim assemblies under the vehicle door slam Key Life Test (KLT) environments. The CAE Virtual Door Slam Test (VDST) procedure simulates the environment of a whole door structural assembly, as a hinged in-vehicle door slam configuration. It predicts the durability life of a plastic door trim sub-assembly, in terms of the number of slam cycles, based on the simulated stresses and plastic material fatigue damage model, at each critical location. The basic theory, FEA methods and techniques employed by the VDST procedure are briefly described in this paper. Door trim project examples are presented to illustrate the practical applications and their results, as well as the correlation with the physical door slam KLTs. The successful application of CAE virtual KLT has demonstrated that VDST can reduce product development time and cost, by evaluating and improving the durability of plastic door trim components at early design stage, before a prototype is made and physically tested. |
An Application of Car Crash Test Technology to a Causal Investigation of a Revolving Door Accident | On March 26, 2004, a fatal accident occurred when the head of a 6-year-old child was trapped in a large revolving door in a high-rise building in Tokyo. To investigate the cause of the accident, Prof. Yotaro Hatamura, representing Hatamura Institute for the Advancement of Technology, gathered experts in various fields including architecture and door manufacture, and initiated the “Door Project,” with the cooperation of the building company. Nissan Motor Co. participated in this project, and conducted load measurement tests on various doors. Applying car crash test technology, including production of special door test dummies and high-speed photography, it was possible to simulate the accident while taking human movement into account. As a result, we obtained important data for accident cause investigation. In this paper, we report the results of application of car crash test technology through an introduction of test results on various doors, and envisage the possibility of future contribution of this technology to man-machine safety issues. |
Modeling of Door Slam Noise Index by using Sound Quality Metric | Door slam noise is very important sound, because Door Slam noise gives a big effect in high-class feeling of vehicle and brand identity. But it is very difficult to analyze door slam noise by traditional analysis and overall sound level. Moreover, the short occurrence time of Door Slam noise makes the analysis more difficult. In this paper, we used the latest developed sound quality methods for analyzing Door Slam noise. And we had performed jury test for luxury vehicles. After that we had carried out correlation analysis between objective analysis and subjective test. Finally, we could suggest Door Slam noise Index by linear regression analysis. |
Simple Test Method for Squeak & Rattle Evaluation of Door Trim by Using Statically Repeated Loading Robot Arm | Recently, major car maker is specified squeak and rattle test method for subsystems or components by objective method. Generally these test method is focused on vibration environmental conditions. Especially, door trim which is located close to occupant is required additional test for squeak and rattle which is produced by occupant's interaction with door trim. To evaluate this condition, generally it can be tested by subjective method such as striking or pushing and twisting several positions of door trim. Dosing so is very time consuming and including variation results as different decisions. So, this paper suggest a new approach for evaluating squeak and rattle which is relating occupant contacting conditions to interior part, especially interior door trim. Multi-axis robot arm is examined to push automatically several points of door trim. Subjective response index for noise is checked at each point and compared with objective values which are evaluated by acceleration level of vibration. Results on subjective and objective method show that they have similar trend at each test point and is thus to adapt to new test method. |
Blind Spot Monitoring by a Single Camera | A practical and low cost Blind Spot Monitoring system is proposed. By using a single camera, the range and azimuth position of a vehicle in a blind spot are measured. The algorithm is based on the proposed RWA (Range Window Algorithm). The camera is installed on the door mirror and monitoring the side and rear of the host vehicle. The algorithm processes the image and identifies range and azimuth angle of the vehicle in the adjacent lane. This algorithm is applied to real situations. The 388 images including several kinds of vehicles are analyzed. The detection rate is 86% and the range accuracy is 1.6[m]. The maximum detection range is about 30[m]. |
Optimization of MAC Side Window Demister Outlet by Parametric Modelling through DFSS Approach | In recent years clearing the mist on side windows is one of the main criterions for all OEMs for providing comfort level to the person while driving. Visibility through the side windows will be poor when the mist is not cleared to the desired level. “Windows fog up excessively/don't clear quickly” is one of the JD Power question to assess the customer satisfaction related to HVAC performance. In a Mobile Air Conditioning System, HVAC demister duct and outlet plays an important role for removing the mist formation on vehicle side window. Normally demister duct and outlet design is evaluated by the target airflow and velocity achieved at driver and passenger side window. The methodology for optimizing the demister outlet located at side door trim has been discussed. Detailed studies are carried out for creating a parametric modeling and optimization of demister outlet design for meeting the target velocity. In this methodology, a parametric modeling of demister outlet design using the factors such as length, width, vane angles and demister outlet to window angle is created using CATIA. Design for six sigma methodologies is followed for robust optimization and arrive at the combination of appropriate design factors which influences the velocity at side windows. L18 orthogonal design array matrix has been created and flow simulations are carried out using the commercial CFD software STAR CCM+. The impacts of each design factors and levels on the side window velocity have been analyzed extensively and best combination of design factors have been found out. Parametric modelling of demister outlet significantly aids in reducing the manual design time for simulation by 50% and DFSS approach helps in finding out the optimized design factors of demist outlet during the design phase of new programs. |
A New Method of Characterizing Wind Noise Sources and Body Response for a Detailed Analysis of the Noise Transmission Mechanism | Interior noise caused by exterior air flow, or wind noise, is one of the noise-and-vibration phenomena for which a systematic simulation method has been desired for enabling their prediction. One of the main difficulties in simulating wind noise is that, unlike most other noises from the engine or road input, wind noise has not one but two different types of sources, namely, convective and acoustic ones. Therefore, in order to synthesize the interior sound pressure level (SPL), the body sensitivities (interior SPL/outer source level) for both types of sources have to be considered. In particular, sensitivity to the convective input has not been well understood, and hence it has not been determined. Moreover, the high-frequency nature of wind noise (e.g., the main energy range extends up to 4000 Hz) has limited the effective application of CAE for determining body sensitivities, for example, from the side window glass to the occupants’ ears. This paper presents a new approach to the analysis of wind noise which has been restricted by the intrinsic nature of the noise sources (i.e., a mixture of convective and acoustic components). To cope with this dual-input complexity, a new transmission model was built to treat noise sources characterized simply as “forces” impinging upon the body surfaces regardless of the type of source and noise transfer functions (NTFs) employed as body sensitivities to the forces. This model enables a quantitative synthesis of interior noise and also a contribution analysis of the sources and/or body sensitivities with high accuracy. |
Vibration Design of Experiments with Varying Factors on a Panel-Beam System | Both vehicle roof systems and vehicle door systems typically have viscoelastic material between the beams and the outer panel. These materials have the propensity to affect the vibration decay time and the vibration level of the panel with their damping and stiffening properties. Decay time relates to how pleasant a vehicle door sounds upon closing, and vibration level relates to how loud a roof boom noise may be perceived to be by vehicle occupants. If a surrogate panel could be used to evaluate decay time and vibration level, then a design of experiments (DOE) could be used to compare the effects of different factors on the system. The purpose of this paper is to show the effect of varying test factors on decay time and vibration level on a panel-beam system with viscoelastic material applied. The results were calculated using DOE software, and they were used to construct optimized systems for validation testing. The test regimen used a modal hammer to excite the system and a piezoelectric accelerometer to measure the response. The input force measured with the modal hammer was used to normalize the structural responses. The conclusions of this work are presented and examined. |
Interior Noise Reduction in a Passenger Vehicle through Mode Modulation of Backdoor | Inside cabin of a passenger car, low frequency booming noise still presents a major hurdle for NVH engineers to fine tune a vehicle. Low frequency booming noise is presently taken care with addition of mass damper and large reinforcements. These conventional countermeasures add weight to the vehicle as well as increase the overall production cost. The study presented in this paper proposes a countermeasure model that not only reduces the booming noise but also avoids any weight and cost addition. It has been focused for low frequency booming noise around 30 ∼ 40 Hz. Within the range mentioned, one of the major reasons for booming noise in hatchback models is the bending resonance of backdoor. By modifying the mode of the backdoor in such a manner that it cancels the effect of bending on the vehicle acoustic cavity, improvement can be achieved in terms of sound pressure level at the driver’s right ear location (DREL). Present study utilizes an innovative approach to change the bending mode of the backdoor into twist mode. This has been achieved by offsetting the latch and striker assembly from conventional center location to either side on the transverse axis. The study has been done on a correlated full vehicle trimmed model of a subject vehicle. Maximum improvement of 6 dB(A) has been achieved through the proposed countermeasure. The countermeasure has been applied horizontally to all hatchback models having a backdoor that opens downside-up. The effect of the countermeasure was found to be substantial. |
Novel Aircraft Ground Operation Concepts Based on Clustering of Interfaces | The projected uptick in world passenger traffic challenges the involved stakeholders to optimise the current aviation system and to find new solutions being able to cope with this trend. Since especially large hub airports are congested, operate at their capacity limit and further extensions are difficult to realise. Delays due to late arrival of aircraft or less predictable ground operation processes disrupt the airport operations in a serious way. Various concepts improving the current turnaround processes have been presented thus far, whereby radical aircraft design changes have little chances for realisation in the short term. By maintaining the established overall aircraft configuration, the concepts promote higher probability to become commercially available for aircraft manufactures and operators. Based on a clustering of aircraft interfaces, such as doors and service panels, for state-of-the-art passenger aircraft, concepts targeting to reduce the required resources and time are presented. First studies show that relocating and installing wider passenger doors allow shortening the passenger egress and ingress process by up to 55% compared to current short-to-medium haul aircraft. From a cabin layout point of view, a merger of two galleys and spatial separation from the cabin entrance area would enable a parallelisation of de-/boarding and catering operations which save up time to 20%. The implementation of these single improvements radically shortens the average turnaround time by almost 55% for a full-service carrier and 32% for a low-cost carrier scenario. Furthermore, weight penalties due to additional installed aircraft systems are translated into block fuel deltas of around +0.3% on a 500 nm (926 km) trip. The presented concepts promote a large improvement potential to turnaround time with minor-to-moderate aircraft modifications as well as a higher level of process robustness and thus have the potential to increase airline revenues. |
Design Methodology of an Automotive HVAC Mechanism and Its Numerical Validation Using Multibody Simulation | In order to ensure a comfortable space inside the cabin, it is very essential to design an efficient heating ventilating and air-conditioning (HVAC) system which can deliver uniform temperature distribution at the exit. There are several factors which impact on uniformity of temperature distribution. Airflow distribution is one of the key parameter in deciding the effectiveness of temperature distribution. Kinematics links and linkage system typically termed as ‘mechanism’ is one of the critical sub-systems which greatly affects the airflow distribution. It is not the temperature uniformity but also the HVAC temperature linearity also depends on airflow distribution. Hence the design of mechanism is incomparably of paramount importance to achieve the desired level of airflow distribution at HVAC exit. The present paper describes the design methodology of automotive HVAC mechanism system. To this context various parameters which contribute in designing the mechanism were studied and then a layout was made in CAD. Further the design was evaluated numerically using the MBD (multibody dynamics) of Hypermesh software from which torque to drive the mechanism was predicted as well the reaction force at doors. The design was fine tuned to reduce the operating effort. Finally the predicted operating effort was validated by making the physical sample and it is found that numerical results are in good agreement with that of experimental results. So adoption of such methodology in the early stage of design ensures better and better design of automotive HVAC system. |
Closures weatherstrips with variable cross sections | Closures systems performance is a trade-off between NVH (Noise, Vibration and Harshness) and DCE (Door Closing Efforts) requirements. Dynamic sealing performance and sheet metal rigidity are the key contributors for a stable system. The seals actuate like a spring on the system. Higher seal load is good for NVH performance, adding more dumping to the system, but it will negatively affect DCE, as it will demand additional energy to close the system. Nominal seal load must be defined to achieve a balance between these attributes. This study is about dynamic sealing profiles with variable seal load, which provides tunable solutions to address the trade-off between NVH and DCE on the side doors or rear closures. Dynamic sealing weatherstrips are made of sponge EPDM extruded profiles with a specified load, defined by its CLD (Compression Load Deflection), which is given by the cross section design. While standard extrusion process produces a single cross section profile, a new extrusion technology provides the possibility of varying the profile cross section along the extrusion, thus the possibility to have different CLDs along the length of door perimeter. This technology can assist on the issues that demand quick solutions on vibrations and load relieves, providing good results for these critical attributes. Timing and costs are very attractive as well on the small car segments. |
Aeroacoustics of Heavy Duty Truck Side Mirrors - An Experimental Study | Side mirrors are a known source of aerodynamically generated noise in vehicles. In this work we focus on mirrors for heavy duty trucks, they are large, often not designed with main focus on aero-acoustics and are located in a cumbersome position on the up-right A-pillar of European trucks. First the test method itself is discussed. To allow fast and cost effective design loops a bespoke vehicle, where the powertrain is separated from the cab, is developed. This vehicle can be run on a standard test track. While running the tests the wind speed is monitored, any variations are then compensated for in the post processing allowing averaging over longer time periods. For the mirror tests the door of the vehicle was especially trimmed to reduce other transmission paths into the cab than the side window. Additionally other possible aeroacoustic sources were reduced as much as practically possible. The generated wind noise was monitored with surface microphones both on the mirror (in the wake) and on the window. Additionally arrays of microphones were placed inside the cab and also accelerometers on the window. First the method is evaluated using a dummy mirror that basically is a Strouhal tone generator. Then actual mirrors were tested. It is seen that although the hydrodynamic turbulence noise dominates at the surface microphones on the window, the noise that actually is seen inside the cab is the acoustic sources generated by the separation around the mirror and A-pillar and convected at the speed of sound to the window. |
Localization of BSR Noise Source Using the Improved 3D Intensity Method | A three-dimensional (3D) sound intensity probe is used to identify the trim components generating buzz, squeak, and rattle (BSR) noise in a vehicle interior. The 3D intensity probe has the advantages of compact overall size, small number of microphones, and low-frequency detection capability. Although the 3D sound intensimetry has been not popularly applied in practical problems due to various bias errors, a new error compensation method is adopted in this work, substantially improving the estimate’s precision. Linearization of the phase function of the cross-spectral density function between a set of two microphones is used to calculate the intensity avoiding spectral bias error, and an error map for spatial angles is used to compensate for the difference in directivity index around the microphone array. An intensity probe with an even microphone spacing of 30 mm in tetrahedral arrangement is used for the source localization. The interior space is usually a nearly dead room in terms of absorption, but the reverberation effect cannot be neglected due to the small space. Experiments are conducted by using the artificially generated and edited signals pertaining the typical characteristics of each BSR noise. Various source positions are selected, such as the instrument panel, door hinge, seat, etc., and the sound levels of the source and background are changed. The estimated bearing angles of the noise sources are analyzed on a two-dimensional plot. It is found that the localization error is generally less than 6°, which demonstrates the full possibility of using this improved 3D intensity technique for the localization of BSR noise sources in the real time. |
NVH Analysis of Lightweight Steel Components in Full Vehicle | With tighter environmental regulations, as well as political and public opinion pressure, the reduction of automotive polluting gas emissions is subject to intense debates and interests. Before a potential transition to full electrical vehicles as the long term solution, the reduction of mass remains of prime importance to permit direct reduction of emissions in internal combustion engine (ICE) vehicles. In addition to the challenges of structural integrity and safety issues, the acoustical and vibration performance of vehicles can be greatly influenced by mass reduction. This article presents a case study of lightweight design of an automotive door with a high strength steel thin gauge outer panel. An experimental comparison between a reference and a lightweight door was conducted in a complete vehicle, allowing assessing the potential effect of the mass reduction on the acoustic and vibrational performances. Several conditions were assessed: rolling on different surfaces, transient events such as heavy vehicle crossing and door closing events. The comparison method included the determination of main transfer paths on the full vehicle. The study indicated that the different acoustic and vibration performances of the vehicle were preserved. |
Full Vehicle NVH CAE Methodology Development to Address Tailgate Rattling on a Future Tata SUV | In recent years, car manufacturers have been working intensively on new ways to improve the quality of interior trims. Elimination of squeak and rattle has become one of the main concerns for car manufacturers lately, given the significance of these incidences in customers' perception of overall quality. Traditionally, rattle problems are found and fixed with physical tests at the late design stage, mainly due to lack of up-front CAE simulation prediction methodology and tools availability. This article presents a finite element based methodology for the improvement of rattle performance of a vehicle tailgate. In this study, appropriate finite element (FE) modeling technique was introduced to accurately predict occurrence of tailgate rattle. Simulation process using commercial software “Nastran” employing modal and forced frequency response analyses was illustrated. Design modifications were incorporated for performance improvement of rattling on present and future SUVs. The simulation methodology and results were validated with experiments on an existing SUV model, with BSR inputs at left rear tire and acceleration responses measured on body and tailgate. Usefulness of this study to predict tailgate rattling in future SUVs was underlined with an example. |
A Test Methodology for Vehicle Wind Noise Reduction and Acoustic Quality Improvement | Aeroacoustics of vehicles is becoming an important design criterion as it directly affects passenger’s comfort. The wind noise at highway speeds (>80 KMPH) is a critical quality concern under normal and crosswind conditions and dominant factor in assessing acoustic comfort of the vehicle. Wind noise is caused by the vortex air flow around a vehicle body and air leakage through the sealing gaps of attached parts. This majorly contributes to high frequency noise (>250 Hz). Accurate identification and control of noise sources and leakage paths result in improved acoustic comfort of the vehicle. In this paper, aero-acoustic quality characteristics of validation prototype vehicle are studied. The major wind noise sources and leakage paths in the vehicle are identified through in-house blower set up in the semi anechoic room. The overall wind noise level and articulation index of vehicle at various speeds are determined through on- road measurements. The improvement in the vehicle articulation index (AI) by 14% and reduction in noise level by 4 dB (A) are achieved through design modification of seals, door structure and trim parts. |
Design of Automotive Structures Using Multi-Model Optimization | The use of structural optimization in the design of automotive structures is increasingly common. However, it is often challenging to apply these methods simultaneously for different requirements or model configurations. Multi-model optimization (MMO) aims to simplify the iterative design process associated with optimizing multiple parts or configurations with common design variables especially when conflicting requirements exist. In this paper, the use of MMO is demonstrated to evaluate the feasibility of an automotive door concept using an alternative material. |
Vibration Fatigue for Chassis-Mounted, Cantilevered Components | Vehicle chassis mounted cantilevered components should meet two critical design targets: 1) NVH criterion to avoid resonance with road noise and engine vibration and 2) satisfied durability performance to avoid any incident in structure failure and dysfunction. Generally, two types of testing are performed to validate chassis mounted cantilevered component in the design process: shaker table testing and vehicle proving ground testing. Shaker table testing is a powered vibration endurance test performed with load input summarized from real proving ground data and accurate enough to replicate the physical test. The proving ground test is typically performed at critical milestones with full vehicles. Most tests are simplified lab testing to save cost and effort. CAE procedures that virtually replicate these lab tests is even more helpful in the design verification stages. A method for defining load input, Power Spectral Density or Sine Sweep, to predict the fatigue life of chassis component will be discussed. The CAE process for this topic, with an air suspension compressor support bracket as an example, is presented for vibration stress and fatigue as well as a process to predict and correlate a vibration shaker table key life test. |
Simulation and Optimization Driven Design Process for S&R Problematic - PSA Peugeot Citroën Application for Interior Assembly | NVH (Noise Vibration & Harshness) is one of the main focus areas during the development of products such as passenger cars or trucks. Physical test methods have traditionally been used to assess NVH, but the necessity for reducing cost and creating a robust solution early in the design process has driven the increased usage of simulation tools. Development of well-defined methods and tools for NVH analysis allows today’s OEMs to have a virtual engineering based development cycle from concept to test. However, a subset of NVH problems including squeak and rattle (S&R) have not been generally focused upon. In a vehicle, S&R is a recurring problem for interior plastic parts such as an instrument panel or door trim. Since 2012, Altair has been developing S&R Director (SnRD), which is a solution that identifies and combats S&R issues by embedding the Evaluation-Line (E-Line) methodology [1] [2]. This methodology is based on industry best practices, as described in the paper SAE 2012-01-1553. This simulation based approach consist of predicting the risk of S&R for trim parts, identifying the root causes, and proposing solutions to the projects via robustness analysis and optimization. This type of simulation integrates design & manufacturing data (GD&T) as well as advanced material testing data. |
Cabin-Ambient Air Exchanges and Their Relation to In-Vehicle CO 2 Concentration | It is common for users of commuting passenger cars in Thailand to use the vehicle’s HVAC (Heating, Ventilating and Air Conditioning) system predominantly in recirculation (REC) mode. This minimizes the compressor work, thereby saving fuel, and reduces dust and odor infiltration into the vehicle cabin. The car windows are rarely opened for ventilation purposes, except for exchanges at service stations such as garage entrances and tollway booths. As such, there are few opportunities for fresh air to enter the cabin with the consequent accumulation of CO2 in vehicle cabins due to occupants’ exhalations being well documented. Field experiments conducted showed that the in-vehicle CO2 concentrations could reach up to 15 times that of the ambient concentration level during typical city commutes. Preliminary experiments were also conducted to quantify the air exchanges between the cabin and the ambient when the doors are opened for occupant egression. The results indicated that the amount of air exchange depends on the prevailing wind speed and direction, the number of doors opened, and the duration of the door opening. |
Prediction of Mirror Induced Wind Noise Using CFD-FEM Approach | Wind noise is becoming important for automotive development due to significant reductions in road and engine noise. This aerodynamic noise is dominant at highway speeds and contributes towards higher frequency noise (>250Hz). In automotive industry accurate prediction and control of noise sources results in improved customer satisfaction. The aerodynamic noise prediction and vehicle component design optimization is generally executed through very expensive wind tunnel testing. Even with the recent advances in the computational power, predicting the flow induced noise sources is still a challenging and computationally expensive problem. A typical case of fluid-solid interaction at higher speeds results into broadband noise and it is inherently an unsteady phenomenon. To capture such a broad range of frequency, Detached Eddy Simulation (DES) has been proven to be the most practical and fairly accurate technique as sighted in literature. Present work talks about the application of Detached Eddy Simulation (DES), as a computationally faster and cheaper method for predicting the flow and sound generation. In the present case a mirror mounted on SUV has been investigated numerically using Finite Volume Code, FLUENT in flow domain and FEM methodology with appropriate aero acoustic analogies in structural domain. In this study, the effect of mirror configuration on the vehicle interior noise has been presented. The analysis has been carried out on baseline mirror, new mirror (door mounted) and no mirror cases. The average sound pressure level inside the vehicle observed to be reduced by 17% with door mounted mirror compared to baseline mirror case. |
Stiffness Simulation Techniques and Test Correlations in Automotive Interior Cockpit Systems (IP, Door Trim and Floor Console Assembly) | An automotive cockpit module is a complex assembly, which consists of components and sub-systems. The critical systems in the cockpit module are the instrument panel (IP), the floor console, and door trim assemblies, which consist of many plastic trims. Stiffness is one of the most important parameters for the plastic trims' design, and it should be optimum to meet all the three functional requirements of safety, vibration and durability. This paper presents how the CAE application and various other techniques are used efficiently to predict the stiffness, and the strength of automotive cockpit systems, which will reduce the product development cycle time and cost. The implicit solver is used for the most of the stiffness analysis, and the explicit techniques are used in highly non-linear situations. This paper also shows the correlations of the CAE results and the physical test results, which will give more confidence in product design and reduce the cost of prototype testing. |
A Case Study for Automotive Door Closing Effort Uncertainty Analysis based on Monte Carlo Simulation Method | Quality in the automotive industry means development and manufacturing of vehicles whose specifications meet customer requirements. Among many other quality issues, door closing effort is a vehicle characteristic that strongly affects the customer first opinion about vehicle design. The door closing effort is affected by uncertainties in materials and manufacturing processes. The present paper presents a reliability-based method to evaluate the uncertainties associated with door closing effort due to manufacturing processes. A formulation is proposed to calculate that energy based on three components: energy used to compress air into the vehicle, energy used to compress the sealing and energy used to lock the door. In order to quantify the probability that the door closing effort is greater than a target value, reliability analysis concepts are used based on the uncertainties associated to latch position. The Monte Carlo simulation is used to define door closing effort variability due to variation of the side door latch position. That analysis allows defining maximum allowable latch and striker position variability in order to keep door closing effort below a target value. The latch position uncertainty is modeled by a probability distribution defined based on data collected from the assembly process. The probability of having a door closing effort magnitude lower than a target value is then calculated. Simulated distribution is compared to experimentally door effort analysis showing very good agreement between them. The simulation based model is used to evaluate the feasibility of manufacturing processes changes to reduce door closing effort. |
Simulating Human Body Touch Automotive Tests Using Industrial Robot & Intelligent Grippers Equipped With Sensors | All Automotive companies conduct various performance and Endurance tests on automotive bodies, doors by using Pneumatic Actuators. These Actuators can only give linear or rotary motion. Therefore these can neither simulate the complex motion of Human arm nor can they simulate the Force and pressure induced by the Human palm or Human back on the body domain parts. Each test need to have different test setup. This paper discusses how a system of industrial Robot coupled with intelligent Gripper with sensors and feedback signal to robot can be used to simulate the effect of Human touch during testing. |
Motor Control in Auxiliary Drive Systems How to Choose the Best Fitting Electronic Solution | In modern vehicles, the number of small electrical drive systems is still increasing continuously for blowers, fans and pumps as well as for window lifts, sunroofs and doors. Requirements and operating conditions for such systems varies, hence there are many different solutions available for controlling such motors. In most applications, simple, low-cost DC motors are used. For higher requirements regarding operating time and in stop-start capable systems, the focus turns to highly efficient and durable brushless DC motors with electronic commutation. This paper compares various electronic control concepts from a semiconductor vendor point of view. These concepts include discrete control using relays or MOSFETs. Furthermore integrated motor drivers are discussed, including system-on-chip solutions for specific applications, e.g. specific ICs for window lift motors with LIN interface. In most cases, system suppliers have the choice between several electronic partitioning concepts, based on specific technical and economic conditions up to given specific preferences of the supplier. |
Supporting Hinge Arrangement for Heavy Weight Side Opening Tailgate | The tailgate is the fifth or the rearmost door of an SUV (Sports Utility Vehicle)[1]. It can be side opening or top opening. It is attached to the BIW (Body In White) with two hinge arrangement. The hinges are designed to take the cantilever load of a normal side opening tailgate along with the passenger ingress/egress load. This means that apart from the doors own weight, the hinges have to take the extra load which a passenger exerts on it by resting his/her forehand on the handle. The hinges are designed to take these loads and under normal circumstances, they do not fail for acceptable number of cycles of opening and closing of the tailgate. But in case of an armored vehicle side opening tailgate, it is quite a challenge for the normal hinges to take the heavy load of the tailgate along with passenger ingress / egress load. The normal hinges (Refer figure-1) obviously fail under such heavy loads either in their design or material configuration. To take this extra load, designers had to think of an innovative arrangement/concept that was simple yet convenient from retrofitting point of view on an armored vehicle configuration. Such an innovation was thought off, designed and implemented successfully on first prototype of the armored SUV. Figure 1 Figure showing the view of a portion of a tailgate from outside of the SUV. Normal hinges are visible as shown in yellow color. Also visible is the aperture plate of the arrangement in blue. (BIW not shown.) |
An Improved Methodology for Calculation of the Inertial Resistance of Automotive Latching Systems | This paper outlines an improved methodology to perform calculations to verify the compliance of automotive door latch systems to minimum legal requirements as well as to perform additional due diligence calculations necessary to comprehend special cases such as roll over crashes and locally high inertial loadings. This methodology builds on the calculation method recommended by SAE J839 and provides a robust and clear approach for application of this method to cable release systems, which were not prevalent at the time J839 was originally drafted. This method is useful in and of itself but its utility is further increased by the application of the method to a Computer Aided Design (CAD) template (in this case for Catia V5), that allows some automation of the calculation process for a given latch type. This will result in a savings of time, fewer errors and allows for an iterative concurrent analysis during the design process. |
The Topology Optimization Analysis on Rope-Wheel Glass Lifter | Glass lifter is a key part of automobile door system. Guide rail is the carrier of glass lifter, and it bears various load cases when glass lifer works. Mass, stiffness and natural frequencies are the factors that influence the performance of glass lifter. In order to design a lighter and reasonable glass lifter, topology optimization methods are studied in this paper. In a rope-wheel glass lifter, design domain is determined by the mechanical structure and working conditions. Firstly, the single target continuum structure topology optimization mathematic models of guide rail are built in this paper, and analysis of multi-stiffness topology optimization are carried out accordingly in which volume fraction is set as 0.4, 0.5 and 0.6. These models are based on SIMP (Solid Isotropic Material with Penalization) theory. Secondly, multiobjective topology optimization models of guide rail are built to consider the influence of dynamic characteristics, and volume fraction is also set as 0.4, 0.5 and 0.6. These models are based on the weighted compromise programming approach. A new formula is proposed in this paper, and optimization objectives are static stiffness and dynamic frequencies, constraint is volume fraction. Comparing these two methods, single target optimization method is more efficient, whereas the structures of optimized guide rail are not reasonable due to the appearance of a large minimum density area in the middle of guide rail. The topology optimization method of considering dynamic characteristic makes the structures of the optimized guide rail more reasonable. The structural load path is clear, and more triangular structures generate which strengthen stiffness of the structure. In addition, values of optimized compliance are lower than that of the single target topology optimization and the first three order frequencies of multi-objective topology optimization are higher than that of single target. So the topology optimization method of multi-objectives makes guild rail have better rigidity and vibration characteristics, which provides a valuable basis and method for the design of guild rail. |
Development of Paint-Less Black Gloss Decorative Technology for Frame Molding | The need to add more color variations to the traditional black gloss has increased globally in recent years. The intention is for automobile manufacturers to differentiate their products in terms of appearance design. The most noticeable trend is to add embellishment around the front grill. The same trend can be seen in the areas around vehicle doors. It is most common to use a coating material to emphasize the black gloss. However, in overseas countries it is a challenge to meet the required appearance quality, and under the current circumstances CKD is imported from Japan to meet such requirements. Recently, a new film-transfer technique has been established that can express black gloss as well as any coating material by transferring the roughness of the film surface. It is achieved by crimping the PET film onto the vinyl-chloride surface after the extrusion molding is performed. Moreover, we have successfully localized this technique and reduced the manufacturing cost. Thus, the development process will be described. |
Closure Slam CAE Method Investigation for Automobiles | In the current scenario, the major thrust is to simulate the customer usage pattern and lab test using virtual simulation methods. Going ahead, prime importance will be to reduce the number of soft tool prototype for all tests which can be predicted in CAE. Automotive door slam test is significantly complex in terms of prediction through simulation. Current work focuses on simulating the slam event and deriving load histories at different mounting locations through dynamic analysis using LSDyna. These extracted load histories are applied to trimmed door Nastran model and modal transient analysis is performed to find the transient stress history. This approach has a significant advantage of less computation time and stress-convergence with Nastran for performing multiple design iterations compared to LSDyna. Good failure correlation is achieved with the test using this approach. Using these load histories, design improvements are evaluated and robustness of the approach is validated. An attempt is made to extract load histories using virtual mule in LSDyna. So, at an early stage in a project, using the only hinge and latch CAD location with closure mass, inertia and center of gravity, the load histories can be extracted and design improvement can be evaluated. Detailed analysis of predicting over-slam through simulation and effect of the position of glass on strain at different locations is highlighted. |
A Multi-Function Automotive MM-Wave Radar Design | A 24GHz multi-function assist system has been developed for advanced automotive radar, which includes different applications in Blind Spot Detection (BSD), Lane Change Assist (LCA), Doors Open Warning (DOW) and Rear Cross Traffic Alert (RCTA). The multi-function radar is based on the micro-strip antenna, which has a reasonable design on main-lobe and side-lobes. According the antenna, the radar can operate in mid-range mode with a high gain and a narrow beam width, whilst performing well in short-range and wide-angle mode. |
Prediction of Aeroacoustical Interior Noise of a Car, Part-1 Prediction of Pressure Fluctuations on External Surfaces of a Car | A wall-resolving Large Eddy Simulation (LES) has been performed by using up to 40 billion grids with a minimum grid resolution of 0.1 mm for predicting the exterior hydrodynamic pressure fluctuations in the turbulent boundary layers of a test car with simplified geometry. At several sampling points on the car surface, which included a point on the side window, the door panel, and the front fender panel, the computed hydrodynamic pressure fluctuations were compared with those measured by microphones installed on the surface of the car in a wind tunnel, and effects of the grid resolution on the accuracy of the predicted frequency spectra were discussed. The power spectra of the pressure fluctuations computed with 5 billion grid LES agreed reasonably well with those measured in the wind tunnel up to around 2 kHz although they had some discrepancy with the measured ones in the low and middle frequencies. The Dynamic Smagorinsky Model (DSM) was adopted for the subgrid-scale turbulence model of LES while the resulting spatially-filtered Navier-Stokes equations of the incompressible fluid flow were solved by a Finite Element Method. In the second paper of this series of studies, the hydrodynamic pressure fluctuations computed on the car surfaces will be used as the unsteady loading for computing the panel vibration of the test car by using Finite Element Method, and finally the interior acoustical fields will be predicted by solving the Helmholtz equation for sound propagation. The contribution from the external acoustical field to the interior noise, which was not simulated by the present incompressible LES-based approach, was estimated based on the acoustic analogy, and was confirmed to be negligibly small compared with those from the hydrodynamic loading in the present case. |
Construction and Kinematics of Automotive Side Door Latch Mechanisms | Automotive side door latches are considered safety-critical systems due to both federal and automotive OEM regulations. The paper presents a kinematical study, in terms of degrees of mobility, and the basic construction for an example mechanism utilized as an automotive side door latch. This system is represented and approximated with mechanisms with articulated bars, cams and gears. Mobility calculations for such type of mechanisms involve both the determination and the investigation of all involved kinematical elements and the nature of their mobile restraints (called kinematical couples). By applying the principles and the methods described in this paper similar investigations in terms of the degree of mobility for other side door latch design applications can be investigated. |
Multi-Objective RBDO for Automotive Door Quality Design | This paper develops a multiobjective optimization methodology for automotive door quality design under uncertainty, in which the tradeoffs between two competing objectives need to be considered. Two important quality issues, door closing effort and wind noise, are of concern and the corresponding probabilities of unsatisfactory performance are considered in the optimization. Model-based reliability analysis methods are used to compute these probabilities. Both component and system-level reliability analyses need to be performed in RBDO. While a first order reliability method (FORM) is found adequate for the reliability estimation with respect to door closing effort, an adaptive Monte Carlo simulation method is found suitable for reliability analysis of the wind noise problem with multiple limit states. An efficient decoupled RBDO approach is used to solve the multiobjective optimization and the Pareto frontier is generated for decision-making. The proposed method can be applied to solve a wide variety of RBDO problems with competing objectives and reliability constraints at both component and system levels. |
The Application of Magnesium Die Casting to Vehicle Closures | During the last decade, advances in magnesium die casting technology have enabled the production of large lightweight thin walled die castings that offer new approaches for low investment body construction techniques. As a result, many OEMs have expressed an interest in magnesium door closure systems due to investment reduction opportunities, coupled with potential weight savings of up to 50%. However, for such applications, product engineers are faced with the challenge of designing for stiffness and strength in crash critical applications with a material of lower modulus and ductility compared to wrought sheet product. Concept designs for side door systems have been presented in the literature, and indicate that structural performance targets can be achieved. However, to date, series production designs feature a multitude of supplementary sheet metal reinforcements, attached to die castings, to handle structural loads. While this approach can still offer performance benefits, the additional cost of tooling and assembly has a negative impact on both overall weight and the business rationale. On the contrary, the magnesium door concepts presented in this paper describe the development of side door systems designed to replace the bulk of sheet metal stampings by a single magnesium die casting. A summary of the design, analysis, prototyping and testing stages is reported, in addition to the development of a series production door system for a 2004 model year vehicle. A review of manufacturing and test results demonstrate how magnesium can be used effectively in the manufacture of low investment, lightweight vehicle closures. |
Detecting and Classifying Secondary Impacts in Door Closing Sound | One of the primary correlates to customer annoyance with door-closing sound is peak loudness. In addition, customer annoyance also increases with the existence of secondary impacts, such as rattles. While these secondary impacts are typically not seen in the time-varying loudness trace (or other common sound quality metrics), it is often possible to visually identify the impacts in a time-frequency display of the door-closing sound. But the reduction of this display information to a single-number objective metric that agrees with subjective assessments has previously proved elusive. This paper summarizes the recent development and application of an objective metric that agrees with subjective classifications of secondary impacts in door-closing sounds. |
Antenna Embedded Door Handle for Smart Key System | It is necessary for a door handle for the smart-key system to adapt for various door handle structures. The smart-key door handle, of course, should have competitiveness. For developing the next generation of the smart-key door handle, we considered that compact sizing and easy manufacturing are the key issues. Therefore, we tried to use the wire harness as an antenna and a sensor for the smart-key system. Moreover, the bending-forming method has been developed to achieve this idea. We will introduce the development process with the commitment to improve commercial value exampling the smart-key door handle development. |
A Study on the Modelling Technique for the Passenger Out-Of-Position Simulation | There was a regulation to reduce injuries caused by airbags for OOP (Out-Of-Position) impact loading conditions. Also, many tests are needed to meet the regulation regarding design variation. And the main effect of airbag design variable has not been well known. Therefore, numerical simulation modelling method and technique were required to reduce the test numbers and recommend the airbag design guideline for OOP condition. To establish modelling procedure for OOP situations in this paper, simulation model was built and correlated with test. Also, the body block test for airbag cushion correlation, a pendulum test for opening stiffness correlation of airbag door and low risk deployment static test using 3-year-old dummy for OOP simulation correlation were performed. And, airbag door and folding condition were evaluated using full factorial DOE (Design of Experimental) technique. Finally, airbag inflator, vent hole, opening stiffness of door and friction coefficient were evaluated using orthogonal array (L9). From the DOE results, the airbag door modelling was insignificant for In-position situation whereas it was significant for OOP modelling. And the direct folded mesh shows a good correlation for OOP condition. Especially, the direct folded mesh by MOBIS folder was validated. The OOP simulation results had been mainly influenced by the inflator model and airbag door opening stiffness. |
SEA Modeling of A Vehicle Door System | The Door system is one of the major paths for vehicle interior noise under a variety of load conditions. In this paper we consider the elements of the door lower (excluding glass) in terms of noise transmission. Passenger car doors are comprised of the outer skin, door cavity, door inner sheet metal, vapor barrier, and interior trim. Statistical Energy Analysis (SEA) models must effectively describe these components in terms of their acoustic properties and capture the dominant behaviors relative to the overall door system. In addition, the models must interface seamlessly with existing vehicle level SEA models. SEA modeling techniques for the door components are discussed with door STL testing and model correlation results. |
Experimental Study On the Energy Flow Analysis of Vibration of an Automobile Door | The Energy Flow Analysis (EFA) can be effectively used to predict structural vibration in medium-to-high frequency range. In this paper, Energy Flow Finite Element Method (EFFEM) based on EFA has been used to predict the vibration of an automobile door. The predicted results for the frequency response function of the door have been compared with corresponding experimental results. In the experiment, the automobile door has been divided into several subsystems and the loss factor of each subsystem has been measured. The input mobility at a source point has been also measured. The data for the loss factors and the input mobility have been used as the input data to predict the vibration of the automobile door with EFFEM. The frequency response functions have been measured over the surface of the door. The comparison between the experimental results and the predicted results for the frequency response functions showed that EFFEM could be an effective tool to predict the structural vibration. |
Low Frequency Transient CAE Analysis for Vehicle Door Closure Sound Quality | Improvement of vehicle door closure sound quality is one of the major customer wants. It is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to design for a specific sound target. In this paper, a CAE tool is developed based on transient FEA and BEA for the analysis of structural-borne vehicle door closure sound quality in the low frequency range (up to 300Hz). Design sensitivity analysis (DSA) are performed for investigating effects of major design variable changes on the door closing sound quality. A SUV model was studied to validate the simulation results and to demonstrate the capability of the developed CAE tool for providing design guidelines on door closing sound quality. |
The Door Mounted Inflatable Curtain | It has been shown that Inflatable Curtains have the potential to reduce head injuries in side impacts and the system has accordingly been introduced on a growing number of car models. There is also a potential benefit in rollover situations. This paper only consider performance in situations with belted occupants. To date, it has not been possible to implement an Inflatable Curtain in convertible vehicles because they lack a roof. The challenge of the Door Mounted Inflatable Curtain (DMIC) has been to overcome the lack of support and fixation possibilities offered by a roof. This paper includes a description of the DMIC and how it was integrated into the vehicle structure. The paper will also show how to create the space and support needed to utilize the internal stiffness and make it possible to fill the bag in time. The impact attenuation and ejection protection functions of the DMIC will be demonstrated. |
Benefits of a New Concept Window Lift System in a Typically Constrained Door Environment | A new design concept for a mechanism to raise and lower side dropping automotive windows provides greater in-board/ outboard compliance than conventional window lift systems. These design aspects provide advantages over current technologies. Among these advantages are: A reduction and control of vectored load inputs on the associated window lift system, having the effect of improved efficiency. A lower cost construction than conventional devices. A window lift system that is more capable of providing one-touch-up functionality meeting the anti-pinch safety criteria outlined in the Federal Motor Vehicle Safety Standard (FMVSS) 118. Drastically reduced prototyping time. This reduction is achieved by producing a general purpose product, then shaping / modifying it to approximate door geometry. The freedom of the inboard / outboard constraints makes imperfect geometry inconsequential in the evaluation of the prototypes. The method of research includes data collection of comparative systems and demonstrations of performance. a general financial analysis contrasting with conventional systems. direct comparative examples, along with anecdotal examples of actual prototype lead times. This new concept window lift regulator system, known as the Racklift™ system, due to its combination of material construction, mechanical drive geometry, low weight, consistently low power consumption, and dual axis directional flexibility, is unique in its ability to address these various functions and quality of operation. The conclusions drawn support the effects of reduced load variation as measured through velocity, current draw, noise variation, and seal wear. The conclusions also demonstrate the financial advantages and rapid prototyping of the device over conventional systems. |
An Assessment of Door Openings in NASS-CDS Resulting From Combined Longitudinal Compressive and Lateral Tensile Latch Loading | The April 1st, 2005 Global Technical Regulation (GTR) [ECE/TRANS/180/Add.1] Working Party for door locks and door retention components reviewed a combination loading static bench test for latch systems (combination test) that is capable of evaluating the strength of the latching systems and is designed to detect fork bolt detent bypass failures. In the combination test, the latch is mounted on a flat steel plate that moves horizontally. The striker is mounted on a vertically moving ram device. During the test, lateral tension of 6,650 N is applied and maintained on the coupled latch-striker system by moving the flat steel plate and then applying a longitudinal compressive force of 16,000 N by moving the striker at a constant rate. A study of field data from the National Automotive Sampling System - Crashworthiness Data System (NASS-CDS) data files for the years 2003 to 2007 was conducted to determine the prevalence of real world crashes with latch/ striker separation due to a loading environment similar to that in the combination loading test. The study also assessed whether requiring door latches to pass this combination test would translate into a significant safety benefit by reducing deaths and injuries that result when a vehicle occupant is ejected from a vehicle during a crash. Data was limited to later model year vehicles (1995+) and to cases that comprised the necessary information needed to determine impact location, direction, and severity. A total of 330 NASS-CDS cases from 2003 to 2007 were coded with at least one door latch/ striker separation. Photographic evidence and crash parameters were utilized to determine whether each door latch/ striker separation was due to loading environments represented by the combination loading test. Of the 330 cases of latch/ striker separations, 290 cases occurred in very severe crash conditions with significant vehicle damage. The latch/ striker separation in these cases was deemed to have resulted from excessive loads and vehicle deformation. Of the remaining 40 latch/ striker separation cases, only 14 had loading conditions similar to that simulated in the combination loading test for latch systems. This study also found that in recent years there has been a trend that clearly reflects a significant reduction in both the number of door latch/ striker separations and the deaths and injuries that are traceable to these failures. As a result of the small number of cases identified and the trend toward reduced numbers of door latch/ striker separations, this study found that imposing a requirement that door latches pass the combination test would prevent 1.38 to 5.37 fatalities and 0.98 to 27.20 serious injuries per year. |
CAD - Based Synthesis of a Window Lifter Mechanism | The kinematic layout is an essential part in the early development phase of an automotive door. Apart from the door opening mechanism, the main focus lies on the synthesis of the window lifter, which has a high impact on the glass shape and on window tightness properties. The main task is to find a proper window motion with respect to the space requirements and the maximum seal deflection. Boundary conditions are given by the shape of the pillars and the window which are mainly styling driven. In this contribution a method is described to compute an optimized motion allowing for all such restrictions. The applied method is based on a CAD platform and combines simulation with parametric-associative design. This leads to a high level of flexibility and simple handling. The presented approach is an example of an upfront design analysis significantly supporting the door development process. |
Pressure Sensor Simulation Capability for Side Impact Sensing Calibration | There is a growing interest in using pressure sensors to sense side impacts, where the pressure change inside the door cavity is monitored and used to discriminate trigger and non-trigger incidents. In this paper, a pressure sensor simulation capability for side impact sensing calibration is presented. The ability to use simulations for side impact sensing calibration early in the vehicle program development process could reduce vehicle development cost and time. It could also help in evaluating sensor locations by studying the effects of targeted impact points and contents in the door cavity. There are two modeling methods available in LS-DYNA for predicting pressure change inside a cavity, namely airbag method and fluid structure interaction method. A suite of side impact calibration events of a study vehicle were simulated using these two methods. The simulated door cavity pressure time histories were then extracted to calibrate the side sensing system of the study vehicle. The calibration result shows that both the airbag method and the fluid structure interaction method are capable of predicting the pressure change inside the door cavity for side impact sensing calibration purposes, albeit the former requires much less computer run time than the latter. |
A Simple Method to Calculate Vehicle Heat Load | The first challenge to properly size a vehicle A/C system is to define the vehicle air conditioning heat load requirement. Within automotive industry, a model to accurately define vehicle heat load is still under development. In this study, a simple method to calculate vehicle heat load is developed. The cooling load temperature differential (CLTD) method[1] is used to calculate the heat gain of a sunlit roof and wall (door). This is done in one step by using ASHRAE data. The calculation presented here takes into account the geometrical configuration of the vehicle compartment including glazing surfaces (shading), windshield and roof angle, and vehicle orientation, Special attention is given to the calculation of direct and diffuse incidence solar radiation through the windshield and skylight glass. The vertical glass' solar heat gain is evaluated by using ASHRAE[1] data. The U value method is used to calculate heat transfer between the outside and inside cabin. Heat gains from infiltration, occupant, and HVAC unit blower motors are considered in the cooling load calculation. The method accuracy was validated using wind tunnel tests. The results showed the predicted cooling load is very close to the tested value, and the deviation between calculated and tested heat loads is smaller with fresh air mode than that with recirculation mode. |
Control of Airborne Road Noise Using Sealers | Noise generated during tire/road interaction has significant impact on the acoustic comfort of a vehicle. One of the most common approaches to attenuate road noise levels consists on the addition of mass treatments to the vehicle panels. However, the acoustic performance of sealing elements is also relevant and has an important contribution to the noise transmission into the vehicle interior. In this paper the correct balance between the mass added to treat vehicle panels and sealing content is investigated. The procedure to quantify the critical road noise transmission paths consists of recording interior noise levels as applied treatment is removed from potential weak areas, such as wheelhouses, floor, doors and body pillars. It is observed that the noise propagation through body pillars has a direct influence on road noise levels. In this case, the use of acoustic sealers placed in the body pillar sections can reduce noise transmission particularly at high frequencies leading to the achievement of desired vehicle acoustic comfort levels. |
Objective chime sound quality evaluation | Customer perception of vehicle quality and safety is based on many factors. One important factor is the customers impression of the sounds produced by body and interior components such as doors, windows, seats, safety belts, windshield wipers, and other similar items like sounds generated automatically for safety and warning purposes. These sounds are typically harmonic or constant, and the relative level of perception, duration, multiplicity, and degree of concurrence of these sounds are elements that the customer will retain in an overall quality impression. Chime sounds are important to the customer in order to alert that something is not accomplished in a right way or for safe purposes. The chimes can be characterized by: sound level perception, frequency of the signal, shape of the signal, duration of the “beep” and the silence duration. The purpose of this work is to use psychoacoustic parameters and time-frequency tools in order to quantify the sound quality perception of chime sounds like key off headlamp on and the unclosed door with gear out of parking mode. |
A Novel Test Rig for the Aerodynamic Development of a Door Mirror | Door mirrors have a small but measurable contribution to the overall aerodynamic drag of a road vehicle. Typically for passenger cars and SUVs this is in the range 2.5–5%. It can be difficult to refine the shape of door mirrors as the improvements are, sometimes, too small to measure with any accuracy. A test rig has been developed which allows a full size door mirror to be tested in a model wind tunnel facility, which has better balance resolution, where the mirror is mounted to a partial vehicle body. This also results in a faster and cheaper method to develop shapes for door mirrors. The rig is described and the initial correlation tests presented. The limitations of the rig and some further applications are discussed. |
Design of Dual Sliding Door for a Small-size Car and Its Validation Using CAE Tools | Sliding doors are usually employed on the rear side of minivans and some large vehicles for easy egress and ingress. Furthermore, dual sliding doors are frequently observed in various concept models. This paper describes design of a dual sliding door for a small-size car. A new sliding mechanism with two sliding contact points is proposed with the B-pillar incorporated in the door structure made of high strength steel. Two sliding tracks are located in the door and the rocker panel. The door linkages first swivel and then slide with the help of the rollers in the tracks to open the door. The sliding mechanism and the door structure were validated using CAE tools such as HyperMesh, MSC/NASTRAN [2] and LS-DYNA[3]. This validation process was divided into three parts: (1) Dynamic Stiffness Analysis or the normal mode analysis to understand the natural frequency response of the door. (2) Static Stiffness Analysis or the Door Sag analysis was conducted to see the structural strength of the door in static loading. Finally, (3) Quasi-static side intrusion analysis was performed to see the resistance of the door structure against an intruding pole. The analysis results showed that the door structure achieved the desired structural performance requirements. |
Automotive Side Glazing for Primary and Secondary Occupant Retention | The occupant retention performance of laminated and tempered side glazing during rollover collisions is analyzed. A brief history of automotive glazing is given, including a discussion of current technology. A summary of glazing failure mechanisms is provided, along with the results of impact and quasi-static pushout testing of undamaged commercial and prototype door windows. The investigation shows that supported laminated side glazing gives performance comparable to windshield glazing and can effect both primary and secondary containment of occupants. Results of documented unplanned rollover collisions and staged rollover tests are presented in support of the conclusions drawn. |
Touch Feel and Appearance Characteristics of Automotive Door Armrest Materials | This paper presents results of a five phase study conducted to evaluate touch feel and appearance of door armrest materials. Seven different production door armrests with different material characteristics such as softness, smoothness, compressibility, texture, etc. were evaluated. In the first phase, the subjects seated in a vehicle buck in their preferred seating position with the armrests adjusted at their preferred heights, provided ratings on a number of touch feel and appearance of the door armrest materials using 5-point semantic differential scales. In the second phase, the armrests were presented to each subject in all possible pairs and they were asked to select preferred armrest material in each pair. In the third phase, pressures in the armrest contact area were measured in three armrest usage postures, namely: i) lower arm supported on the armrest (not holding the steering wheel), ii) elbow resting on the armrest while grasping the steering wheel, and iii) the subject attempting to reposition in the seat while pushing his/her elbow against the armrest (maximum possible pressure). Pressure measurements (peak, average and contact area) were made for 12 subjects using XSENSOR pressure mapping digital mat. The fourth phase involved evaluation of all the touch characteristics in the dark to eliminate any visual influence. And finally, in the fifth phase, the subjects were asked to rank order important characteristics of the armrest materials. Some results of the studies are: a) The 95% confidence intervals of 5-point ratings discriminated different armrests on each characteristic defined by adjective pairs such as Smooth/Rough, Compressive/Non-Compressive, Plain/Textured, Fine/Coarse, etc. b) Correlation analyses revealed a number of relationships between the variables (e.g. Soft/Hard ratings were highly correlated with Compressive/Non-Compressive ratings, Cheap/Expensive ratings were correlated to Fake/Genuine, and Pleasing/Non-Pleasing ratings; but Texture/Plain were uncorrelated with Cheap/Expensive or Fake/Genuine ratings). c) The pressure measurements data showed: i) Under normal forearm resting posture the average and peak pressures ranged between 3 to 10 psi and 4 to 25 psi, respectively. ii) With the elbow resting on the armrest while holding on the steering wheel, the average and peak pressures ranged between 4 to 19 psi and 5 to 40 psi, respectively. iii) While repositioning in the seat, the average and peak pressures ranged between 5 to 17 psi and 10 to 40 psi, respectively. d) Evaluations of touch feel conducted in the dark, differed from those from those conducted using both touch and visual sensory cues. |
Measuring the Pitch of Door Closing Sounds - The Sound Quality Issue of Door “Thump” | This paper discusses a partially completed project that was begun shortly before an unexpected retirement opportunity appeared that limits the possibilities for follow-up work. The project was to investigate the pitch of door closing “thump.” The impetus for the investigation was a paper by Gardner and Magnasco. Their paper described an instantaneous frequency decomposition method that they used in the study of bird song and human speech. Bird song or speech may not seem to be closely linked to measuring door closing thump but the speed with which the frequencies in door closing sounds change is not that different from the speed of frequency change in bird song or speech. Two questions that immediately arise are can Gardner and Magnasco's technique resolve the low frequency components that occur in door closing sounds and, if so, do they relate to human perception of thump? This paper can only present a brief look at the encouraging results from preliminary work to answer the first question. Further work is needed to completely answer the two questions and either confirm or reject the technique. |
Optimization of Mirror Angle for Front Window Buffeting and Wind Noise Using Experimental Methods | Door mirrors have a major impact on wind noise observed at the driver's ear. The mirror distance and angle with respect to the front side glass will influence the front window buffeting characteristics of the vehicle as well. Optimizing the mirror angle to minimize or eliminate buffeting while maintaining acceptable wind noise performance can provide additional customer satisfaction. Changes to the mirror angle were investigated experimentally for both wind noise and buffeting effects. Experimental vehicle interior noise and buffeting data was taken at multiple yaw angles and wind speeds using a full scale aero acoustic wind tunnel. In addition, experimental wind noise attributes for the different mirror angles was also used to determine the optimal angle. The resulting angle measurement will be used as a best practice mirror angle for optimal wind noise and front window buffeting performance on future vehicle programs. |
Capacitive Sensing in an Automotive Environment | Capacitance sensing in motor vehicles allows for protection in power windows, sunroofs, liftgates and sliding doors. It also provides greater design freedom of operator interfaces that include switch entry and fingerprint sensing. Fingerprint sensing adds new levels of security for the access and starting of a vehicle thus allowing for the elimination of keys. This paper describes the design and operation of various systems that could employ capacitive sensing technology including keyless entry, operator controls, and safety related sensing. Also discussed are vehicle installation, safety enhancement, and ergonomic benefits. |
Rapid Prototyping Applied to Parts Used in Static Tests of Racks for Packing and Transporting Automobile Parts | This work was motivated by the specific needs of a materials flow and packing planning sector (PFME), within a manufacturing engineering department of a vehicle assembly company in Brazil. In this sector, there is a growing need to obtain prototype parts in the shortest time and at the lowest cost possible in order to carry out static prototype tests of the special packing and transportation racks used in this company, since these racks need to be ready to assist the preparation phase of the series production of the vehicle. The objective of this work is to survey the academic theory and the existing literature in order to find an application proposal of rapid prototyping (RP) techniques to make the parts used in the rack tests, thus reducing time and acquisition costs. For that purpose, some limiting conditions were considered: first, the application of the RP technique is limited to the external parts of the vehicle, such as doors, front and back hoods, and fenders; second, the consulted suppliers should be available in the domestic market. Finally, a proposal of work systematics for the assembly company is presented. |
Design of Door Latching and Locking Systems for Crashworthiness | Several sub-systems in a vehicle contribute to vehicle crashworthiness. One such system is the door latch and locking system. Correct functioning of this system is critical for facilitating occupant evacuation and preventing occupant ejection during crashes. Special care needs to be taken during vehicle safety development to achieve the desired intent. In crashes, it is observed that door opening or locking mainly occurs on account of inertial loads and deformation of the door structure. This paper studies the possible failure modes and their causes. Some likely solutions have also been discussed with a case study. |
A Case Study About Side Door Closing Sound Quality | Side Door Closing Sound Quality is one of the first impressions a potential customer has about a vehicle. It can enhance an impression of robust and high quality vehicle. This paper is a study of Side Door Closing Sound of a specific vehicle model. The main objective is to understand how Door Closing Sound Quality varies over several vehicles samples and how to improve the design and/or production process in order to achieve better Sound Quality. Two vehicles (same model) with distinct performance have been chosen among several samples. Both have been evaluated and the physical differences are weighted to realize what really matter for Door Closing Sound Quality. |
Investing Factors Affecting Door Slam Noise of SUV and Improved Performance by DFSS Approach | Recent development in automobile industries has seen increased customer attention for good door slamming noise. One of the constituent which plays major role in building brand image of vehicle in terms of NVH performance is door slam noise quality. Hence it is very desirable to understand how different door elements radiate sound during a door-closing event and how to optimize a door structure to achieve specific sound target in order to ensure the door closing noise quality, NVH engineers needed to look at contributions from different door subsystems. The use of statistical tools like Six Sigma can further help them to ensure the consistency in results. This paper explains the systematic approach used to characterize different element of door which contributes to the overall door slam noise quality through QFD (Quality Function Deployment) and contribution analysis. The different mechanisms contributing to door slam noise were studied. NVH characteristics (Acoustic transfer Function and Point Mobility) of the door structure and mounting locations were captured for correlating with the time - frequency spectrum of door slam event. Wavelet analysis was performed on door impact event to determine the critical frequency band contribute to noise. DOE (Design of Experiments) was constructed based on the analysis of results. Prototype modifications were conducted, the results of which are discussed in the paper together with their relative importance to work improvement in door closing noise. Finally the design intent solutions were developed together with component supplier and are validated on vehicle. |
Investigation of Airflow Induced Whistle Noise by HVAC Control Doors Utilizing a ‘V-Shape’ Rubber Seal | Doors inside an automotive HVAC module are essential components to ensure occupant comfort by controlling the cabin temperature and directing the air flow. For temperature control, the function of a door is not only to close/block the airflow path via the door seal that presses against HVAC wall, but also control the amount of hot and cold airflow to maintain cabin temperature. To meet the stringent OEM sealing requirement while maintaining a cost-effective product, a “V-Shape” soft rubber seal is commonly used. However, in certain conditions when the door is in the position other than closed which creates a small gap, this “V-Shape” seal is susceptible to the generation of objectionable whistle noise for the vehicle passengers. This nuisance can easily reduce end-customer satisfaction to the overall HVAC performance. The goal of this paper is to establish (1) contributing factors, (2) correlation of the whistle noise generation to the Strouhal number, and (3) an empirical equation to predict the whistle frequency as a function of fan speed and door gap geometry. Several potential solutions are also presented. |
A Finite Element Method for Effective Reduction of Speaker-Borne Squeak and Rattle Noise in Automotive Doors | Increasing sound quality with advanced audio technology has raised the bar for perceived quality targets for minimal interior noise and maximal speaker sound quality in a passenger vehicle. Speaker-borne structural vibrations and the associated squeak and rattle have been among the most frequent concerns in the perceived audio quality degradation in a vehicle. Digital detection of squeak and rattle issues due to the speaker-borne structural vibrations during the digital vehicle development phase has been a challenge due to the physical complexity involved. Recently, an effective finite element method has been developed to address structure-borne noise [1] and has been applied for detecting the issues of squeak and rattle in passenger vehicles due to vehicle-borne vibrations at vehicle, component and subcomponent levels [2, 3, 4, 5, 6, 7, 8]. In this paper, the speaker-borne structural vibrations are simulated accurately by adapting the critical audio loads in terms of equivalent structural excitations. The squeak and rattle analysis method is extended to predict the potential squeak and rattle issues in a door system on which the speaker is mounted. Using the method, the root causes for the issues are identified and counter-measures are developed to improve the audio quality in the system effectively. Audio tests are conducted to confirm the improvement in the audio quality with the counter-measures adapted. The finite element predictions show very close correlation with the tests regarding the squeak and rattle issues with the baseline design as well as the audio quality enhancement with the counter-measure. |
Gear Lever Sound Quality Evaluation | Vehicle sound quality has become lately one of the main topics of study in the automotive industry which is associated with the quality of the product. Into the automotive development the static operational sound quality is one of the attributes that is considered. The sounds produced through the manipulation of items like the doors and interior components (windows, seats, safety belts, windshield wipers, and others) generated for safety and warning purposes are items related to the vehicle quality for customers. Those sounds based on relative level of intensity, duration, harmony and degree of contribution are elements that the customer will retain in mind, an overall quality impression. The sound produced during gear lever manipulation is important to the customer in order that the event should transmit low intensity and robust and soft impression. The purpose of this work is to evaluate this kind of event using binaural recordings inside the vehicle through subjective and objective evaluations. Psychoacoustic parameters (loudness, sharpness and roughness) and time - frequency spectrum (Wavelet transform) are proposed to correlate objective results with the subjective perception of gear lever sound quality. |
Constant Q Transform for Automotive NVH Signal Analysis | The constant Q transform consists of a geometrically spaced filter bank, which is close to the wavelet transform due to the feature of its increasing time resolution for high frequencies. On the other hand, it can be processed using the well-known FFT algorithm. In this sense, this tool is a middle term between Fourier and wavelet analyses, which can be used for stationary and non-stationary signals. Automotive NVH signals can be stationary (e.g., idle, cruise) or non-stationary, i.e., time-varying signals (e.g., door closing/opening, run-up, rundown). The objective of this work is to propose the use of the constant Q transform, developed originally for musical signal processing, for automotive NVH (run up, impact strip and door closing) time-frequency analyses. Also, similarities and differences of the proposed tool when compared with Fourier and wavelet analyses are addressed. |
The Use of a Simply Vibration Analysis Method for Optimization of Vibration Damping Material in Vehicle Panels | With the use of common office software a simplified vibration analysis method is implemented. This method makes possible a quick evaluation of the data obtained with structural dynamics testing measurements, showing the maximum values of Frequency Response Functions (FRF) and a spatial graphic representation for these maximums; with this the regions of strong vibrations are identified. The dimensions and placement of the damping material to be applied in a metallic panel is defined based in the identification of these regions of maximum vibration. Successive tests can be quickly carried out with this method, making possible to achieve the better solution for elected frequencies. The application of this methodology in the optimization of damping material placement in vehicle doors results in a considerable enhancement in closing door noise. |
Innovative Steel Solution for Doors | Reducing CO2 emissions, improving safety, reducing car weight and cutting costs are the main constraints in the design of a new door. In partnership with a design office and a Tier 1 supplier, Arcelor has designed a generic door that reduces mass by 15% without impacting costs. This design was based on a reference (D segment / one of the European “best in class”). Functional validation was achieved by comparison with this reference and industrial feasibility was validated with the help of a partner (industrial door manufacturer). A range of innovations were implemented: This presentation will describe Design principles, Functional validation Industrial feasibility. |
Cost-Effective Day & Night Marking Using Lasers | “Day & night marking” is used in automobiles, aviation, instrumentation and computer keyboards to make buttons and controls (e.g. door locks, window controls, sound system adjustments, etc.) clearly visible under ambient illumination conditions varying from bright sunlight (day) to low light (night). Although it sounds simple, manufacturing these products cost-effectively in a small-batch production environment requires the use of a sophisticated, automated, laser-based tool. |
The Effect of Seal Stiffness on Door Chucking and Squeak and Rattle Performance | Traditionally, door seals are designed to achieve good wind noise performance, water leakage and door closing effort in a vehicle design and development process. However, very little is known concerning the effect of door seal design on vehicle squeak and rattle performance. An earlier research work at Ford indicates a strong correlation between the diagonal distortions of body closure openings (in a low frequency range 0 - 50 Hz) and overall squeak and rattle performance. Another research at Ford reveals that relative accelerations between door latch and striker in a low frequency region (0 - 50 Hz) correlate well with door chucking performance. The findings of this research work enable engineers to assess squeak and rattle and door chucking performance using vehicle low frequency NVH CAE models at a very early design stage. This paper is concerned with a sensitivity study of door chucking and squeak and rattle performance with respect to door seal stiffness using two performance metrics (diagonal distortions at closure openings and relative accelerations between latch & striker) mentioned above. It is found that door chucking performance improves with the increase of seal stiffness monotonically. Whereas overall squeak and rattle performance is dictated by match boxing modes of doors and liftgate that are in turn affected by seal stiffness. No special trend is observed in terms of squeak and rattle sensitivity with respect to seal stiffness. |
Advanced Thermoplastic Composites for Automotive Semi-Structural Applications | Composite materials have found applications in the aviation industry because of an appropriate combination of properties - high stiffness, high heat performance and lower specific gravities. The Automotive industry has similar needs, and the application of composites in semi-structural application is a natural next phase. This is also necessitated because of global emphases on fuel efficiency and safety considerations in automotive applications. In this paper, thermoplastic composite material technology solutions and case studies for a number of applications, such as front-end-modules, door modules and instrument panel carriers are presented. Since processing and material modeling of composites is of critical importance in the design process, this paper also describes a new definition of isotropic properties of long glass composites, and perhaps the only way of honestly comparing such materials. This method is now accepted as an European Alliance for Thermoplastic Composite (EATC) standard. |
Application of Transient SEA for Vehicle Door Closure Sound Quality | Transient Statistical Energy Analysis (SEA) is applied as an analysis technique and compared to measured data in this study. A transient SEA model for a door closure event is developed and compared to measured data to validate this model with measured acoustic and vibration responses. The validated model is then used to predict the effect of changes to component absorption, damping, stiffness, materials, and other properties. The basic theory of transient SEA and the transient SEA model used in the study are described, the validation between analytical model and measured data is shown, and the conclusions from the analysis of design changes to the vehicle components using this model are presented. |
Cab Roof Strength Evaluation—Quasi-Static Loading Heavy Trucks | This SAE Recommended Practice describes the test procedures for conducting quasi-static cab roof strength tests for heavy-truck applications. Its purpose is to establish recommended test procedures which will standardize the procedure for heavy trucks. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included. |
Direction-of-Motion Stereotypes for Automotive Hand Controls | The purpose of this SAE Recommended Practice is to present design recommendations for the direction-of-motion of hand controls found in passenger vehicles, multipurpose vehicles, and trucks. These recommendations are based on recent and past human factors research and are important considerations in the design of control layouts. |
Cranes—Access and Egress | This recommended practice specifies criteria for steps, stairways, ladders, walkways, platforms, handrails, handholds, guardrails and entrance openings which permit access to and from operator, inspection or maintenance platforms on mobile cranes parked in accordance with the manufacturer’s instruction. It also presents requirements for guards and restraints as related to moving parts. |
Ambulance Modular Body Evaluation-Quasi-Static Loading for Type I and Type III Modular Ambulance Bodies | This SAE Recommended Practice describes the test procedures for conducting quasi-static modular body strength tests for ambulance applications. Its purpose is to establish recommended test practices which standardize the procedure for Type I and Type III bodies, provide ambulance builders and end-users with testing procedures and, where appropriate, provide acceptance criteria that, to a great extent, ensures the ambulance structure meets the same performance criteria across the industry. Descriptions of the test set-up, test instrumentation, photographic/video coverage, and the test fixtures are included. |
Automated Fastening of Aircraft Cargo Door Structures with a Standard Articulating Robot System | The demand of flexible and cost-efficient solutions for automated fastening systems inspired us to develop the robot and end-effector technology to fulfil the customer's requirement for a highly accurate, automated robot based drill and fastening system for an aerospace application. This paper describes an innovative robot cell for drilling and solid riveting installation in cargo door structures of a single aisle aircraft at EUROCOPTER in Germany. The required absolute positioning accuracy is reached by using a special compensation package for the robot that was developed by BROETJE-Automation. Our customer's application required a completely new type of end-effector; installing solid rivets and capable of operating within the inner structure of the cargo doors. This solution demonstrates how standard robots equipped with a mature compensation method by BROETJE-Automation resulted in a highly flexible and cost-efficient light weight automation response. |
Re-Design for Automotive Window Seal Considering High Speed Fluid-Structure Interaction | Automotive window seal has great influence on NVH (Noise-Vibration-Harshness) performance. The aerodynamic effect on ride comfort has attracted increasing research interest recently. A new method for quantifying and transferring aerodynamics-induced load on window seal re-design is proposed. Firstly, by SST (Shear Stress Transport) turbulence model, external turbulent flow field of full scale automotive is established by solving three-dimensional, steady and uncompressible Navier-Stokes equation. With re-exploited mapping algorithm, the aerodynamics pressure on overall auto-body is retrieved and transferred to local glass area to be external loads for seals, thus taking into account the aerodynamics effect of high speed fluid-structure interaction. This method is successfully applied on automotive front window seal design. The re-design header seal decreases the maximum displacements of leeward and windward glass with 9.3% and 34.21%, respectively. The improvement of fitting stability shows the effectiveness this seal re-design considering high-speed fluid-structure interaction. |
Mass Benchmarking Using Statistical Methods Applied to Automotive Closures | Understanding the lightweighting potential of materials is important in making strategic decisions for material selection for a new vehicle program. Frequently benchmarking is done to support these decisions by selecting a reference vehicle which is believed to be mass efficient, then using the teardown mass data to set targets for the vehicle under design. In this work, rather then considering a single benchmark vehicle or a small set of vehicles, we looked at a large sample of vehicles over a range of sizes and segments (approximately 200 vehicles). Statistical methods were used to identify mass drivers for each subsystem. Mass drivers are the attributes of the vehicle and subsystem which determine subsystem mass. Understanding mass-drivers allows comparisons across vehicle size, segments, and materials. Next, we identified those vehicles which had subsystems which were much lighter than the average after adjusting for mass drivers. This set was defined as mass-efficient designs. We then focused on the lightweighting gained by material selection for these mass-efficient designs. This paper focuses on four body closures systems: side door, hood, decklid, and hatchback door. Results include the identification of mass drivers and predictive equations for closure structure mass for both average designs and mass efficient designs; The influence of material selection on mass for both average and mass-efficient designs; and observations on the diminished mass savings achieved at the system level when there is a mass savings due to material substitution at the structure level. |
Effect of load slope time (LST) and load adaptor position (LAP) on side door strength of passenger cars: A deformation mapping matrix (DMX) approach | Side impact collisions are one of the most frequently occurring road accidents leading to occupant injury and even death. To provide better safety to occupants during such collisions, side doors and side body structures in modern passenger cars have been designed to absorb the impact energy and reduce the depth of intrusion into the passenger compartment. Side impact performance components are often evaluated by conducting a dynamic full vehicle crash test and a quasi-static side door intrusion test. The Indian regulation for side impact performance evaluation comprises of the quasi-static side door intrusion test. This paper highlights the variation in crush strength performance viz., initial crush resistance, intermediate crush resistance and peak crush resistance, due to the difference in the rate of load application as per IS12009:1995. The paper presents the deformation mapping matrix (DMX) approach to study the variation in results due to load slope time (LST) and load adaptor position (LAP). |
Simplified Side Impact Test Methodologies for Door Interior Trim Armrest in Automotive Vehicle | The complete evaluation of the side vehicle structure and occupant protection is only possible by the full-scale side impact crash test. But auto part manufactures, such as door trim makers can't conduct the test especially when the vehicle is under developing process. And important information and components for estimating crash performance is restricted. With the proposed design procedure for the door trim by a simple impact test method was demonstrated to evaluate the abdominal injury. In addition to simple test, Euro-NCAP test result that is conducted by referenced full-scale test in Korea is compared with several test results. In conclusion, this simple test method have similar trend for abdominal injury index so that it is possible to present guidelines of door armrest design to carmaker at the early stages of vehicle program development. |
Sealing and Structural Enhancement System for the Rear Cargo Ramp of a C-130 Aircraft | At flight levels above the ceiling of 10,000 feet, during the operational phase of a sensor deployment system for a C-130 aircraft, it becomes necessary to seal the cargo hold to maintain pressure for the safety and comfort of the crew and operators. In order for the sensor deployment System to have full mission support capabilities for DoD reconnaissance needs, a system must be designed where-by the cargo area may be sealed once the system has been deployed. Currently, with the sensor pod in position, the ramp can be closed to within a few inches of the locked position. The door in this position, for stability during flight, must be locked and structurally supported to maintain the aircrafts design requirements. This presents the first of a series of issues that must be examined for the success of the final design. To seal the remaining area, an expanding “bladder-seal” has been developed. This sealing device will ideally include a means of “holding” onto both the upper door and lower ramp of the aircraft simultaneously. The systems presented will create a significant advancement to the capabilities of the existing sensor deployment system for a C-130 aircraft and for the C-130 itself. This design will be completely capable of being used on any C-130 aircraft produced and will have the same universal mounting system as the current sensor deployment system. |
Electromagnetic Field Analysis for Smart Key Antenna | Currently, the drivers are able to control a door lock at a distant point from a vehicle. Recently, a door lock system has been developed to detect an owner approaching and to unlock the door when he/she touches the door handle. In this system, an antenna detects the existence of the owner with an electrical key near the vehicle. Since this detection performance of the antenna (directivity) varies in the operating area, it is essential to recognize directivity and confirm that there is unoperating area. In this report, we describe an example of predictive calculation on directivity of an antenna using the electromagnetic field analysis. |
Retention Characteristics of Production Laminated Side Windows | Field accident data have demonstrated that occupant ejection during vehicle rollover is associated with a high risk of serious and fatal injury. Although it has been demonstrated that seat belt use is highly effective in preventing occupant ejections, it has been argued that occupant containment during rollover can be accomplished with the use of laminated side glazing. This study was conducted to evaluate the retention characteristics of production laminated side windows. The current vehicle fleet was surveyed for vehicles equipped with production laminated side glass. The survey examined relevant window system parameters including glass retention system, glass configuration, and window geometry. A representative subset of five front door systems from several manufacturers was chosen for further evaluation. In addition, one legacy rear door system with laminated glass was included for comparison. Drop tests were conducted on the production component door-glass systems utilizing an 18 kg (40 lb) headform at an impact speed of 24 km/h (15 mph). None of the tested window systems retained the headform under these loading conditions. Given the results of this study, together with the NHTSA's previous measurements of occupant effective mass, it is concluded that production laminated side glass is not an effective barrier to occupant ejection during rollover. |
The Impact of the Digital Human Modeling on the Aircraft Interior Projects | The main objective of this work is to show a broad view of Digital Human Modeling software as a tool for aiding interior design projects for aircrafts. This will be achieved by showing digital manikins and their use during the development project of an aircraft interior. The time allocated to the design stage could be shortened and the costs concerning mock-up fabrication and certification were lowered because of this program's application during the entire process. The influence can be noted because of the ease to study monuments on high-density configurations, usability and accessibility of the door handles and on-board attendant visibility, etc. This paper is merely conceptual and do not involve existing aircrafts data or in development. |
System Level Noise Source Identification and Diagnostics on a Vehicle Door Module | Noise problems are often system issues rather than component issues. Component manufacturers have been putting continued efforts into constantly improving the quality of their products. There are numerous tests and standards to assess the vibro-acoustic performance of individual components. But once all components are put together, the system response might be entirely different from those of individual components. Typical system level testing has primarily been used to identify bad assembled products from good ones. These tests are usually done as part of a quality control process and slow down production. Such tests usually provide little information about the root causes of noise and vibration problems and no insight into improving engineering designs for noise abatement. This paper presents a new way of conducting system level noise diagnoses by using the Helmholtz Equation Least Squares (HELS) based Nearfield Acoustical Holography (NAH) technology [1]. This approach allows for reconstruction of all acoustic quantities, including the acoustic pressure, particle velocity, and acoustic intensity, and creating 3D acoustic images produced by an arbitrary source based on the acoustic pressures measured on a hologram surface at very close range to the source. It enables one to establish a direct correlation between sound and vibration. The current study involves a noise diagnostic test on a vehicle door assembly to understand system level interaction of the motor and the door module to compliment continued efforts to refine the motor to manufacture quieter assemblies. To identify noise sources, a conformal microphone array, covering the entire door surface was used to measure the acoustic pressures. This data was used to reconstruct the acoustic pressure, normal velocity, and acoustic intensity on the door module surface. In particular, the acoustic intensity and normal surface velocity were analyzed to identify the noise sources and understand the noise generation mechanisms. |
Implementation of a correlation technique for fuel tank sled crash test | The fuel tanks produced in sheet metal forming needs to attend safety requirements regarding the vehicle collision. One of the validation tests is the sled crash test. This test is based on the impact of a sled with a certain profile and energy (defined by rules) against a fuel tank. During the crash are evaluated: deformation, internal pressure, cracks, leaks and the energy absorbed. To avoid trial-and-error methods in the product development stage, the use of numerical simulation has increased in the past years and made the validation process faster and cheaper. One difficulty of this procedure for validation of numerical results is the correlation between the level and the deformation mode of the tank, once the internal pressure and the energy can be measured by special sensors. The main objective of this work was to propose a methodology to correlate the deformed geometry of the fuel tank, using a 3D scanner, with the numerical simulation results. The software used to simulate the crash was Radioss, which has a suitable formulation for events involving large non-linearity. The results are promising and the methodology implemented can be used for other products that involves crash test in the validation, such as bumpers and doors. |
Development and Application of an Enhanced SID-IIs Dummy for Analyzing Side Impact Kinematics | Due to the relative high speed and short distance between the door and occupant, side impact presents a challenging task when analyzing the input force from the door to the occupant. The new FMVSS214 Final Rule in 2007 and the new NCAP in 2008 mandated the use of a SID-IIs in the oblique pole impact test and in the rear seat during an MDB side impact test. Therefore, a high-precision measurement and calculation of the three-dimensional dummy kinematics, as well as the interaction of force inside the dummy (internal force) and force exerted from outside the dummy (external force) will help provide efficient evaluation of design requirements for the door trim and supplemental restraint systems that meet legally mandated requirements. This paper demonstrates that the SID-IIs three-dimensional kinematics and external forces can be calculated with a high degree of precision through the addition of angular rate sensors and force transducers, and describes the application of the technique to vehicle development. |
Design of Dual Sliding Door Mechanism for a Small Sized Car | Swing-out doors can easily cause damage to adjacent parked vehicles in tight parking spaces. Also, they are not traffic-friendly when the vehicles are parallel parked on busy road sides. This paper makes an attempt to come up with an innovative to design and develop a mechanism for dual sliding doors for a small sized car. The doors are supported only on two points of contact as compared to the usual sliding minivan doors which have three contact supports for sliding. These two points are called the “Upper control link and Lower support arm”. To open the door, first the door, has to push out by 90 degrees and then it has to slide in the fore-aft direction to open or close. For the doors, a track was placed just below the window at the beltline location and a triangular sub-roller assembly was designed for sliding motion. A rail was placed on the rocker panel of the space frame which has three rollers assembled in such a way that they would compensate for the weight of the door and rigidly secure the door during sliding. This paper explains the mechanism in detail and also discusses safety issues linked to selection of engineering materials for the doors. |
Load Path Considerations for Side Crash Compatibility | Heavier, larger pickups and SUVs are bound to encounter lighter, smaller passenger vehicles in many future accidents. As the fleet has evolved to include more and more SUVs, their frontal structures are often indistinguishable from pickup fronts. Improvements in geometric compatibility features are crucial to further injury prevention progress in side impact. In corner crashes where modern bullet passenger car (PC) bumpers make appropriate geometrical overlap with target PC rocker panels, concentrated loads sometimes disrupt foam and plastic bumper corners, creating aggressive edges. In situations where sliding occurs along the structural interface, these sharp edges may slice through doors, panels and pillars. End treatments for such bumper beams should be designed to reduce this aggressive potential. The experimental comparison presented here demonstrates that load path compatibility can provide a means by which severe door intrusion due to oblique corner impacts may be reduced without severe weight penalties to the vehicles involved. |
A Dynamic Sled-to-Sled Test Methodology for Simulating Dummy Responses in Side Impact | This paper describes the development of a sled-to-sled test methodology to simulate the occupant responses in different side impact cart test modes. For evaluation of various inflatable restraints (Thorax SAB, Head-Thorax Combo SAB, Pelvis-Thorax Combo SAB), the simulation of ‘gap closure’ between dummy and door is desirable to achieve satisfactory SAB performance, besides obtaining good correlation of occupant responses between full-vehicle tests and sled tests. This methodology uses a combination of three sleds - Bullet, Door, and Seat sleds to simulate the entire door velocity profile in two phases - Phase I: Gap Closure till Door-Dummy contact occurs, Phase II: Door-to-Dummy contact till separation. The initial pre-crash distance between dummy-to-door trim is achieved by positioning the Door sled relative to the Seat sled (with dummy). The Bullet sled strikes the stationary Door sled with a pre-determined initial velocity, which accelerates the Door sled to a peak velocity within a predetermined time from contact (also dummy-to-door contact velocity) to simulate Phase-I of the door velocity profile. The Door sled then strikes the stationary Seat sled with Dummy. After door-to-dummy contact, the Bullet and Door sleds are decelerated by a VIA decelerator to simulate the Phase-II of the Door velocity profile. |
Hybrid Design for Automotive Body Panels | The increasing trend for electric mobility adoption brings new challenges to the automotive industry, requiring a new approach to the manufacture processes, materials adopted and adaptation the market needs. The conventional technologies used to manufacture automotive parts imply significant overhead costs (tooling, assembly, etc.) which can only be justified by large series. The need of light and cost effective materials was the driving force of this study, acknowledging that the growth of the electric vehicles market will be driven by price. The study aims to deliver a hybrid design material solution that would offer quality and security to the vehicle, affordable to everyone, developing engineered solutions in terms of design and production process. To the study were considered exterior body panels that are conventionally manufactured by sheet metal stamping or conventional thermoplastic injection, both having associated high investment costs related with tooling. To follow up this case study was defined as constrains that small series should be considered and weight reduction has to be achieved. The adoption of engineered materials leading to hybrid body panel's configuration was studied with increased resistance and reduced weight, using processes with low cost assembly operations and low tooling investment for a start. Structural reinforcement inserts were used on the test case to provide the desired results on the final component behavior. The approach taken, considered different materials and methodologies focusing on the use of DCPD RIM components having as baseline the materials used nowadays in the automotive industry for the same type of exterior body panels. For deeper understanding on exterior panels' state of art, an analysis through several vehicle doors was made, analyzing the materials used and their combination. As a result, different combinations of materials were considered as adequate for weight reduction and for production on small production series. Virtual simulation of two exterior body panels' solutions was done demonstrating the potential of DCPD as a hybrid solution to deliver structural consistence in conjunction with weigh reduction at a reduced cost. |
Automation for Unprecedented Production Rates | Unprecedented rates in Boeing 737 aircraft production have driven a need for an increase in capacity in fuselage manufacturing and assembly. This paper will discuss the requirements by Spirit AeroSystems to add capacity, and the new and upgraded machinery provided by Broetje Automation in response to these requirements. Production areas found to require additional capacity included galley and entry door skin fastening, as well as frame fastening in upper and lower lobes. Three new Mobile Panel Assembly Cell (MPAC) machines were installed in rapid succession for efficient and flexible production of door panels. For frame fastening of upper and lower lobes, three existing machines were taken out of production one at a time for a comprehensive upgrade resulting in process speed increases of more than 40%. |