正面40%偏置碰撞时后排乘员安全性的仿真分析

为了减小后排乘员在偏置碰撞中受到的伤害,运用MADYMO软件建立包括汽车车身、前后排座椅、三点式安全带、汽车地板、后排5%女性假人的某款汽车后排偏置碰撞的乘员约束系统仿真模型。通过样车试验碰撞结果和模型仿真结果进行对标,验证模型的准确性。在此模型基础上,研究分析前排座椅和安全带等参数对后排乘员安全性的影响,并提出了安全带固定点改进方案,结果表明改进后后排乘员的头部HIC15降低14.2%,颈部张力降低14.4%,有效地保护后排乘员安全。     

集中质量-弹簧碰撞模型在汽车被动安全预研阶段的应用

为在车身开发的概念设计阶段明确车辆前碰的安全性目标加速度波形,提出以乘员伤害值确定整车正面碰撞波形的方法,建立包括驾乘人员的车辆集中质量-弹簧(Lumped Mass-Spring,LMS)模型.为确保LMS模型的有效性,将整车有限元模型仿真结果与运动学特性计算结果对比.通过对比前碰加速度波形、刚性墙力以及前舱总的压溃位移,对LMS模型的有效性进行验证.以乘员胸部的乘约效率为优化目标,基于已验证的LMS模型进行关键参数的试验设计分析,从而为车辆前结构的碰撞安全性能设计提供参考.     

商务车正面碰撞有限元分析

按照CMVDR294要求,运用LS-DYNA软件,对某商务车进行整车和乘员约束系统的正面碰撞并行模拟,并与台车和实车的试验结果进行比较,验证所建立的有限元模型的准确性,为整车开发和耐撞性设计奠定基础.     

前排座椅参数设计对后排乘员的安全性仿真分析

为了研究前排座椅参数对后排乘员在正面碰撞时的安全性影响,使用碰撞软件MADYMO建立包括车体、5%女性假人、安全带在内的某款轿车后排乘员正面碰撞仿真模型。通过试验样车碰撞结果与模型仿真结果的对比,验证模型有效性。在此模型基础上,分析前排座椅头枕和靠背参数对后排乘员的HIC、胸部3ms、胸部压缩量和左右大腿力的损伤值影响,得到了前排座椅参数与后排乘员伤害值的关系,提出减小后排乘员伤害的方法。     

汽车侧面碰撞CAE对标分析

为提高整车碰撞安全性能,针对LINCAP工况,将某新车型整车侧面碰撞CAE仿真与试验结果进行对标分析,通过对比可变形壁障及车身侧变形模式、车门变形轮廓曲线、关键点侵入速度等校对有限元模型,验证该侧面碰撞仿真模型的精度和建模方法的有效性.该对标分析可为新车型碰撞安全性能开发的CAE分析提供参考.     

基于逻辑门限值的客车ABS硬件在环测试研究

针对ABS控制器开发过程中纯数值仿真过于理想化,实车试验成本高、周期长等缺点,设计并搭建了客车ABS硬件在环仿真测试系统;系统由xPC目标实时仿真环境、气制动系统及整车动力学模型组成;气制动系统按照真实客车制动系统并配合力传感器搭建;整车动力学模型由轮胎模型、七自由度车辆模型、制动器模型等组成,并利用Simulink建模;在ABS控制策略中引入逻辑门限值控制,在客车ABS硬件在环仿真测试系统上测试了客车在高附着系数、低附着系数及对接路面上的制动情况;试验表明:逻辑门限值控制能很好地将车轮滑移率控制在最佳滑移率附近,具有较好的控制精度及鲁棒性。     

变拓扑柔性多体系统接触碰撞动力学研究

在实际工程领域中存在着大量接触碰撞等非连续动力学问题,现有的解决柔性多体系统连续动力学过程的建模理论与方法,已经无法解决或无法很好解决这些问题.本文基于变拓扑思想,提出了附加接触约束的柔性多体系统碰撞动力学建模理论；通过设计柔性圆柱杆接触碰撞实验,验证了所提出附加约束接触碰撞模型的有效性；针对柔性多体系统全局动力学仿真面临时间和空间的多尺度问题,提出多变量的离散方法,从而提高了柔性多体系统非连续动力学的仿真效率.     

高速列车座椅间距对乘员二次碰撞伤害的影响

为研究高速列车座椅间距对乘员碰撞伤害的影响,在欧洲列车乘员伤害仿真、试验和评价标准的基础上,参考我国列车客室设施与布置,采用MADYMO Hybrid Ⅲ 50％假人,建立高速列车碰撞事故乘员二次碰撞仿真模型．通过仿真分析比较不同座椅间距对乘员伤害的影响．研究表明,合适的座椅间距能减小乘员的HIC（Head Injury Criterion）值和碰撞的相对速度,从而减小乘员伤害概率．     

基于SV2的汽车乘员约束系统仿真模型 可信度验证系统

针对汽车乘员约束系统仿真模型的可信度验证需要大量重复的数据处理和结果分析的问题,基于可信度验证系统（system of verification and validation, SV2）,将100%正碰、40%偏置碰和侧碰工况的分析流程固化,开发汽车乘员约束系统仿真模型可信度验证系统。对100%正碰工况进行试验验证,结果表明：新开发的仿真模型可信度验证系统对模型可信度验证能够提高90%的工作效率,自动生成分析报告,为仿真工程师提供模型改善建议。     

燃料电池城市客车整车控制系统容错研究

为了解决燃料电池城市客车中安全性和可靠性问题,从车辆通信系统和整车控制器两个方面进行容错设计.本文设计并实现具有两条独立的CAN通道容错CAN节点,利用了CAN规范中的故障界定机制实现通道间的有效切换.整车控制器硬件设计采用两个微控制器,设计相应软件使其具有"失效安全"的能力.针对输入驾驶信号和部件信息,整车控制器进行故障诊断和处理,增强了整车控制器自身的故障诊断能力.最后,整车容错系统在整车控制器测试平台进行硬件在环仿真.试验验证了容错设计的有效性.     

A numerical study of occupant responses and injuries in vehicular crashes into roadside barriers based on finite element simulations

Occupant responses and injuries are important considerations in the design and assessment of roadside safety devices such as barriers. Although incorporating occupant responses and injuries into the design of safety devices is highly recommended by the current safety regulations, there are limited studies that directly consider occupant responses and injuries. Crash test dummies are seldom equipped in the state-of-the-art crash testing of roadside barriers and thus occupant responses and injury risks are evaluated primarily based on vehicle responses. In the present work, occupant responses and injuries in automotive crash events were investigated by incorporating crash test dummies into the vehicle model that was used in the finite element (FE) simulations of roadside crashes. The FE models of a Ford F250 pickup truck and a Hybrid III 50th percentile crash test dummy were employed and a passive restraint system was developed in the FE model. The FE model was validated using existing experiments including a sled test and a full-frontal impact test. Simulations of the Ford F250 impacting a concrete barrier and a W-beam guardrail were conducted and the occupant responses were analyzed. Furthermore, occupant injuries were quantitatively estimated using occupant injury criteria based directly on dummy responses and compared to those based solely on vehicle responses. The correlations between vehicle responses and occupant injuries were studied.     

Integrated design technique for materials and structures of vehicle body under crash safety considerations

With the rapid development of the vehicle industry, crashworthiness has become a crucial aspect in vehicle body design. In fact, crashworthiness is a multivariable optimization design problem for a vehicle body, regardless of structure or material. However, when crashworthiness involves a large number of design variables, including both material and structure variables, it is more difficult to deal with. In this paper, an integrated design technique for materials and structures of vehicle body under crash safety consideration is suggested. First, a finite element model of the vehicle body is established according to relevant vehicle safety standards. Then, the material parameters of the vehicle body are set as analytical factors for factor screening. Next, significant factors are obtained using a three-level saturated design integrated with multi-index comprehensive balance analysis and the MaxUr ⁽³⁾ method, with an improved evaluation method. These screened material parameters along with the corresponding continuous variables of the structure, are considered as the design variables of the integrated design of the vehicle body. Both the weight and the crashworthiness properties are set as the design objectives. Optimal Latin hypercube sampling and radius basis functions are utilized to construct highly accurate surrogate models. Furthermore, the non-dominated sorting genetic algorithm II is implemented to seek the optimal solutions. Finally, two cases considering the roof module and the frontal module of a vehicle body are analyzed to verify the proposed method.     

Development of generic multibody road vehicle models for crashworthiness

The crashworthiness analysis of road vehicles requires detailed data of the vehicles that the automotive manufacturers are, generally, unable to release due to commercial or legal restrictions. In the development of passive safety subsystems or substructures, the overall crash response of a vehicle model used to support it, must mimic that of the real vehicle; if this exists, regardless of any particular constructive detail of its structure provided that it is not located in the vicinity of such subsystem. This work proposes a methodology for the development of multibody models of road vehicles, for passive safety analysis, which include all general structural and mechanical features of real vehicles and start by exhibiting impact dynamic responses similar to the top of line vehicles. These vehicle models, designated as generic, do not require the knowledge of most of the particular details of the design of the real vehicle, which the manufacturers are unable to release, but can be adjusted to have crash responses similar to those of the real vehicle. Based on an existing finite element model of a car, which has all constructive features of vehicles of the chosen class, a multibody model is built applying the plastic hinge approach. By using a selected number of crash scenarios, defined in international standards such as the EuroNCAP, selected parameters of the vehicle multibody model are adjusted to ensure a good correlation between its impact responses and those of the finite element model. The crash responses are measured in terms of structural deformations, velocities and accelerations, occupant injury measures and structural energy absorption capabilities. Assuming that the plastic hinge constitutive equations of the multibody model are not exactly known, their parameters are used here as the multibody vehicle model that are adjusted. The methodology proposed is demonstrated by its application to the identification of the vehicle multibody model of a large family car for which the reference vehicle is available as a detailed finite element model.     

Modeling of rollover sequences

Safety restraint systems greatly reduce the potential injury risk during vehicle accidents. One major type of accident still remains without adequate occupant protection: Vehicle Rollover. Since rollover experiments are difficult to perform, rollover models can help to understand this type of accident. It will be shown, that already quite simple models reveal important properties of vehicle rollover. The influence of various parameter variations can be investigated. Based on a simplified modeling approach, it is possible to develop an analytic stability boundary, which helps to detect an imminent rollover. This is the base for future occupant protection systems.A more complete and complex approach of modeling, covering e.g. half and full turns, requires different strategies. To include detailed suspension systems a multi body approach becomes necessary. As an arbitrary rollover is a fully spatial movement, special assumptions like wheel-road contact do not hold for the regarded time interval. To cope with these difficulties, the simulation requires a state space machine to cover the different vehicle conditions (road contact, free flight, one side lift off). The simulation can then switch between the different model structures. With this approach, classical multi-body vehicle models can be extended by special rollover models to gain insight in the mechanisms causing vehicle rollover.     

Reliability-based multiobjective optimization for automotive crashworthiness and occupant safety

This paper presents a methodology for reliability-based multiobjective optimization of large-scale engineering systems. This methodology is applied to the vehicle crashworthiness design optimization for side impact, considering both structural crashworthiness and occupant safety, with structural weight and front door velocity under side impact as objectives. Uncertainty quantification is performed using two first order reliability method-based techniques: approximate moment approach and reliability index approach. Genetic algorithm-based multiobjective optimization software GDOT, developed in-house, is used to come up with an optimal pareto front in all cases. The technique employed in this study treats multiple objective functions separately without combining them in any form. It shows that the vehicle weight can be reduced significantly from the baseline design and at the same time reduce the door velocity. The obtained pareto front brings out useful inferences about optimal design regions. A decision-making criterion is subsequently invoked to select the “best” subset of solutions from the obtained nondominated pareto optimal solutions. The reliability, thus computed, is also checked with Monte Carlo simulations. The optimal solution indicated by knee point on the optimal pareto front is verified with LS-DYNA simulation results.     

Reliability-based design optimization for crashworthiness of vehicle side impact

With the advent of powerful computers, vehicle safety issues have recently been addressed using computational methods of vehicle crashworthiness, resulting in reductions in cost and time for new vehicle development. Vehicle design demands multidisciplinary optimization coupled with a computational crashworthiness analysis. However, simulation-based optimization generates deterministic optimum designs, which are frequently pushed to the limits of design constraint boundaries, leaving little or no room for tolerances (uncertainty) in modeling, simulation uncertainties, and/or manufacturing imperfections. Consequently, deterministic optimum designs that are obtained without consideration of uncertainty may result in unreliable designs, indicating the need for Reliability-Based Design Optimization (RBDO).Recent development in RBDO allows evaluations of probabilistic constraints in two alternative ways: using the Reliability Index Approach (RIA) and the Performance Measure Approach (PMA). The PMA using the Hybrid Mean Value (HMV) method is shown to be robust and efficient in the RBDO process, whereas RIA yields instability for some problems. This paper presents an application of PMA and HMV for RBDO for the crashworthiness of a large-scale vehicle side impact. It is shown that the proposed RBDO approach is very effective in obtaining a reliability-based optimum design.     

Modelling and simulation for mechatronic design in automotive systems

This paper gives an overview of current industry based projects in the field of vehicle modelling and simulation for the mechatronic design of automotive systems. It shows the wide range of applications for analysis and synthesis during the development process, including vehicle systems, vehicle dynamics, occupant safety, adaptive cruise control, hardware-in-the-loop and fault tolerant real-time systems.     

An improved human display model for occupant crash simulation programs

Presented is an improved three-dimensional display model of a human being which can be used to display the results of three-dimensional simulation programs that predict the positions of an occupant during impact of a vehicle. The model allows the user to view the occupant from any orientation in any position during the crash. The display model assumes the usual break up of the body into rigid segments, which is normal for occupant-crash simulation programs, but the shape of the segments in the display model are not necessarily the same as those used in the crash simulation. The display model is proportioned so as to produce a realistic drawing of the human body in any position. Joints connecting the seqments are also drawn to improve realism.