行人腿部保护汽车前部结构优化

为减少人车碰撞事故中对行人的伤害,采用LS-DYNA软件模拟人车碰撞过程,分别模拟了刚性腿型和柔性腿型的碰撞情况,得到行人小腿的伤害规律。同时,针对柔性腿型的分析结果,对汽车前部结构从三个方面进行优化:改进泡沫刚度,行人腿部总得分值提高了10.01%;改变小腿支撑,行人腿部总得分值提高了10.37%;改进保险杠横梁,行人腿部总得分值提高了17.63%。通过改进汽车的前部结构,柔性小腿的碰撞性能得到了优化,为行人保护方面的汽车前部结构设计提供了参考。     

基于组合近似模型的可靠性优化方法在行人柔性腿型碰撞中应用研究

当行人与车辆发生碰撞时,车身最前端的部件将直接与行人下肢腿部发生接触,其设计是满足行人下肢保护要求的关键。然而针对传统要求的基于刚性腿型行人保护车辆前结构设计方法,在应对柔性腿型行人保护要求已呈现明显的局限性。为了提高保险杠结构的柔性腿型保护功能,结合试验设计技术、组合近似建模技术、多目标优化算法和可靠性分析方法,以行人腿部的伤害值最低为优化目标,对车辆前端结构参数进行可靠性优化设计并对优化结果进行试验验证。研究结果表明:优化后的车辆前端结构与原设计相比,行人柔性腿型保护功能得到明显提高,为车辆前端结构的设计与开发提供有效的参考。     

轿车保险杠泡沫密度对行人腿部保护研究

近年来,随着我国汽车行业的迅猛发展,交通事故中行人的死亡率逐年增加,行人保护研究作为汽车安全的新兴领域已经引起了广泛关注,为减少在交通事故中对行人的伤害,基于有限元方法,分别建立汽车前部结构以及小腿冲击器的有限元模型,并采用LS-DYNA软件模拟人车碰撞过程,选取不同的泡沫密度进行仿真模拟,并且与试验进行对比。结果表明,降低保险杠泡沫密度后,汽车前部结构对行人的伤害明显降低,该结论可为汽车前部保险杠的设计提供参考。     

汽车保险杠的结构特性及设计要求的研究

安全、节能、环保，已经成为汽车工业发展的三大主题。汽车保险杠位于汽车前部，是前部碰撞事故中首先接触的部位，在人车碰撞时低对行人的伤害和车车碰撞中减小对车辆的损坏方面起着重要作用。因此，对汽车前保险杠的结构特性进行研究，具有重要的意义。     

基于行人下肢保护的SUV车型前端结构多目标优化设计

当行人与车辆发生碰撞时,汽车前端结构的设计是满足行人腿部保护要求的关键。然而针对SUV车型由于其前端结构特点与普通轿车不同,在应对行人下肢保护要求已呈现明显的局限性。为了提高SUV车型前端结构的行人保护功能,结合试验设计技术、近似建模技术、多目标优化算法,以行人腿部的伤害值指标胫骨加速度及膝部剪切位移最低为优化目标,以膝部弯曲角为设计约束,对车辆前端结构参数进行了多目标优化设计。研究结果表明:优化后的车辆前端结构与原设计相比,有效降低了行人下肢伤害,为车辆前端结构的设计与开发提供了有效的参考。     

满足行人腿部保护要求的保险杠部件改进

介绍我国行人保护推荐标准中的下腿型对保险杠的试验,并对刚性下腿型冲击器模型进行标定,确定其满足标准对试验冲击器的要求。将保险杠总成几何模型合理简化并转化为有限元网格,赋予应变率相关的材料,按照标准选择碰撞点,建立了完整的下腿型对保险杠试验的有限元模型。根据试算结果,对吸能泡沫部件进行改进设计,并应用于仿真分析,验证了下腿型冲击器的各项指标满足行人保护要求;同时根据仿真能量统计得出结论,吸能泡沫部件对于行人腿部保护具有重要作用。并总结了改进吸能部件的方法。     

均分区域法标记试验区域的行人保护试验研究

现阶段我国仍属于人、车混合的交通状况,车辆碰撞事故频繁发生。在车辆与行人碰撞事故中,行人属于弱势群体,加上现阶段车辆缺乏对行人保护的措施,行人伤亡严重。在汽车行人碰撞事故中,行人头部受重伤是造成行人死亡的主要因素;行人腿部受伤是造成行人受重伤的主要因素。基于两款车辆以均分区域法标记试验区域的行人保护头型碰撞测试数据,对其进行分析研究。得到在车辆前期设计时,将吸能空间留得足够大,可减小头型碰撞的伤害值,从而减小对行人的伤害。将理论分析与试验数据相结合,找到影响头型碰撞发动机罩伤害值大小的主要原因为发动机罩距离机舱内部的距离,通过前期造型设计使得发动机罩距离发动机舱内部部件距离足够大,来减小头型碰撞发动机罩的伤害值。     

基于行人保护下腿型的车辆前端结构分析优化设计

行人下腿型伤害是车辆与行人碰撞的主要伤害之一,为了评价该伤害,针对行人保护刚性腿(TRL)和柔性腿(Flex-PLI)两种腿型的结构、伤害指标、试验规程等进行研究分析。分别建立了刚性腿及柔性腿的某车型前端有限元碰撞模型,进行柔性腿试验验证,得到了行人下腿型伤害分析数据并对该车型前端结构进行结构优化。结果表明:车辆前端两侧弧度较大的造型对膝部韧带伤害影响较大;保险杠小腿梁支撑结构的刚度减小,有利于胫骨弯矩指标的减小,可为类似车型的前保险杠结构提供设计参考。     

铝制发动机盖行人保护分析与结构优化策略

基于行人碰撞保护标准在汽车设计中的要求,将铝材料应用于发动机盖,通过CAE仿真分析了铝制发动机盖和钢制发动机盖对行人碰撞头部伤害标准HIC。对铝制发动机盖的结构提出了优化策略,以达到碰撞时保护行人的目的。     

基于行人保护的某微型客车前部结构设计

针对微型客车要满足行人下肢保护的问题,以某款微型客车为研究对象,采用CAE仿真技术建立了行人下肢-车辆碰撞有限元模型,通过LS-DYNA对模型进行了求解,根据结果对碰撞过程及行人腿部伤害进行了分析。同时,针对分析结果和原微型客车的前保险杠系统结构,提出了两种结构优化方案,分别在原车上增加了吸能泡沫加小腿支撑结构和薄壁吸能板加小腿支撑结构。将改进后的结构重新建立了有限元模型代入计算。数据结果表明,两种方案明显提高了该微型客车的行人保护性能,而且薄壁吸能板加小腿支撑结构可以起到更好的保护作用,为微型客车保护行人的前保险杠结构设计提供了参考。     

Design of pedestrian friendly vehicle bumper

Car-pedestrian accidents take thousands of lives worldwide annually. Therefore, pedestrian protection is an important issue in traffic safety. How to consider a pedestrian friendliness vehicle and then propose pedestrian protection methods are urgent works for minimizing pedestrian injury. For designing a pedestrian friendly vehicle bumper, this study adopts the European Enhanced Vehicle-safety Committee/ Working Group 17 (EEVC/WG17) regulations of legform impactor to bumper tests. Analyzing the pedestrian friendliness of a vehicle bumper by using LS-DYNA is described in detail. Simulation results were analyzed to identify the reasons for the unfriendliness. Furthermore, the analysis of the influence of bumper structure on pedestrian leg was performed and then some guideline was suggested. The analyzed models and results obtained could help evaluate pedestrian friendliness of a vehicle and guide the future development of pedestrian friendly vehicle technologies.     

The effect of leg fracture level and vehicle front-end geometry on pedestrian knee injury and response

In this study a MADYMO (mathematical dynamic modelling) model has been used to identify the influence of leg fracture on the injuries sustained by the pedestrian during front end impact with a vehicle. A factorial study of a MADYMO pedestrian and vehicle model are used to investigate the effect of different leg fracture tolerances, geometry, and vehicle compliance on the criteria measured in the European Enhanced Vehicle-safety Committee (EEVC) pedestrian safety tests. These criteria include knee bending, knee shear response, and lower leg bone (tibia) acceleration. The main study examines the spread of typical values of lower limb tolerance based on reported literature and contrasts the response of weaker, low-strength bones, normal tolerance, and limbs which do not fracture. Results show that knee bending angles and therefore ligament strains are significantly increased when fracture does not occur, and are decreased in bones exhibiting a low-strength response. Bone fracture tolerance is shown to be a significant parameter influencing knee bending. The parameters are compared to show that knee shear is significantly influenced by vehicle bumper compliance and that both criteria are heavily influenced by bumper height. Vehicles with more aggressive geometry, higher bumpers, and larger bumper lead were considered for comparative purposes.     

Bumper shape design for pedestrian safety

The main cause of leg injuries is the bumper during car-pedestrian accidents. Bumper geometry and bumper material have the greatest effect on pedestrian leg injury. The first objective of this study is to evaluate the effects of bumper shape on pedestrian leg injuries. This study uses three bumper shapes on three car models to evaluate the effects of bumper geometry on pedestrian leg injury: A Ford Taurus, Dodge Intrepid, and Dodge-Neon. Then, based on the results of the impact between legform and bumper, this study chooses the best bumper shape that results in the least injury to the pedestrian’s leg. The second objective of this study is to design a new bumper. Using some conclusions regarding the effects of bumper shape on the pedestrian leg injuries, a new pedestrian-friendly bumper was designed. This bumper satisfies EEVC/WG17 safety requirements regarding pedestrian leg injuries. The analyzed models and results obtained could help evaluate pedestrian friendliness of a vehicle and guide the future designing and development of pedestrian friendly vehicle technologies.

     

A study on the development of equivalent beam analysis model on pedestrian protection bumper impact

This paper presents a dynamically equivalent beam analysis model on pedestrian protection bumper impact instead of a non-linear finite element impact analysis method. Equivalent beam analysis model was developed by substituting the femur and tibia for dynamically equivalent Euler beam. Dynamically equivalent forces of bumper beam, upper stiffener and lower stiffener are found by a finite element analysis results and applied to the Euler beam model of lower legform impactor. This equivalent beam analysis model was used to obtain a bending angle of lower legform impactor by using finite element beam theory. Peak acceleration of the tibia was obtained by developing an approximate acceleration equation. A linear interpolation of non-linear finite element analysis results considering the dimension variation of bumper beam factors affecting the acceleration was used to get an approximate acceleration equation. The accuracy of this simple analysis model was tested by comparing its results with those of the non-linear finite element analysis. Tested bumper beam types were press type beam and roll forming beam used widely in the current car bumpers. The differences of maximum acceleration of the tibia between the two models did not exceed 10% and the bending angle did not exceed 20%. This accuracy is enough to be used in the early stage of bumper beam design to check the bumper pedestrian performance quickly. Use of equivalent beam analysis model is expected to reduce the analysis time with respect to the non-linear finite element analysis significantly.     

基于行人小腿保护的保险杠结构稳健性优化设计

为了增强保险杠结构的小腿保护功能,提出了将试验设计技术、径向基函数近似建模技术、全局优化算法和基于蒙特卡罗模拟技术的6σ质量设计相结合的稳健性优化设计方法,并应用该方法进行了保险杠结构的优化设计。优化结果表明,该方法大大提高了车辆的行人保护功能。由于在优化过程中考虑了设计变量的不确定影响,该方法比确定性的优化方法更具有可靠稳健性。因此,从一定程度上讲,该方法是一种求解复杂工程问题的稳健性优化设计方法,深入应用该方法能大幅提高产品的设计质量。     

前保系统行人保护小腿碰撞优化

某车需要增加配置在前端保安装两个倒车雷达探头,且该车目前设计状态无下支撑板,基于LS—DYNA软件进行分析该状态下小腿伤害指标胫骨加速度和小腿弯曲角在大多数碰撞点严重超标。经过分析是由于倒车雷达探头本身材料相对刚度较大,且在X向上的长度较长,严重削弱了小腿碰撞过程中的压溃空间。通过调整倒车雷达的布置位置和增加下支撑板的方式来降低保险杠前端的整体刚度来降低小腿的伤害指标,经过验证该方案最终满足行人保护法规的要求。     

满足行人保护的汽车前端系统设计方法

随着对汽车安全性能的重视程度越来越高,汽车制造商也在不断改进车辆本身的行人保护性能,尤其是行人腿部碰撞保护。如何从概念设计到总布置设计全面考虑汽车前端系统的设计就显得尤为重要。文中通过研究小腿碰撞机理,得出相应的造型和总布置设计条件,并且指出EPP材料的应用能够显著提高小腿碰撞性能,更为有效的方法是采用薄壁钢结构,从而为汽车前端系统提供了设计参考。     

基于行人保护的溃缩式前大灯设计研究

在轿车主动安全性设计中,行人和车相撞的过程中的头部保护是一个国内外研究的重点.越来越严格的汽车安全性法规对行人保护提出了更高的要求.针对基于行人保护的溃缩式的前大灯设计进行了研究,采用有限元分析的方法,对行人头部和前大灯撞击进行了仿真.结论是:溃缩式前大灯能够很好地减少头部的伤害值;并在某国产轿车品牌新车型自主开发中得到了成功的应用.