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.

     

基于行人下腿部与汽车保险杠的碰撞研究及优化设计

交通事故中当汽车与行人发生碰撞时,下腿部易受到骨折甚至更严重的伤害.所以行人保护受到越来越多的关注.各大汽车厂商和研究机构也在自身的产品开发中考虑对行人保护的改善.介绍了行人保护法规内容要求和实验要求,并采用仿真方法,建立了行人下腿部撞击器与保险杠碰撞的有限元模型,分析了腿部与保险杠的撞击响应,得到了行人腿部与保险杠相撞时的加速度、弯曲角度、剪切位移等参数,并通过调整保险杠的造型以及保险杠发泡和蒙皮刚度改善车辆前部对下腿部的影响,从而改进对行人腿部碰撞的伤害.     

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.     

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.     

Development and validation of a pedestrian deformable finite element model

Pedestrian protection has become an increasingly important consideration in vehicle crash safety. Pedestrian-vehicle crashes cause a significant number of pedestrian fatalities and injuries globally. Computer models are powerful tools for understanding how to reduce the severity of injuries in such crashes. Real-world studies of pedestrians provide an important source of information for evaluating pedestrian model dynamic performance and ability to reconstruct injury-causing events. This study describes the validation process of deformable pedestrian model using published postmortem human subject (PMHS) trajectory and head resultant velocity corridors, and demonstrates its applicability to pedestrian — vehicle impact research. We implemented the deformable pedestrian model using LS-DYNA finite element code. Based on PMHS data, the pedestrian model is used to validate the displacement trajectories of the head, pelvis, knee and foot. The finite element pedestrian model thus obtained can help assess the friendliness of vehicles with pedestrians in traffic crashes and assist in the future development of pedestrian safety technologies. This paper was recommended for publication in revised form by Associate Editor Young Eun Kim Tso-Liang Teng is a Professo r in the Department of mechanical and automation engi-neer ing and the Dean of engineeri ng college at the Da-Yeh Uni versity, Taiwan. He received a BS (1981), MS (1986) and PhD (1994) from the Chung Cheng Institute of Technology. His research intere sts include design of passive safety systems in ve hicles, crash tests simulation, passenger and pedest rian injuries analysis, design of pedestrian protecti on systems.     

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。     

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.     

基于LS-DYNA的汽车保险杠仿真优化

基于LS-DYNA软件,分析了汽车保险杠建模过程中的关键影响因素,包括网格密度、时间步长、焊点布置和摩擦系数.建立了汽车保险杠的有限元模型并进行了汽车正面碰撞的仿真.通过采用增大壁厚和添加内部加强件,优化了保险杠的吸能能力,对保险杠的防撞设计和整车模型的建立和仿真具有参考意义.     

某商用车橡胶缓冲块优化设计

某商用车前悬架为独立悬架,下摆臂橡胶缓冲块在车辆运行过程中主要起到限位和缓冲的作用。文中基于H yperw orks软件中的O pti Struct模块对橡胶缓冲块进行拓扑优化分析,根据优化结果,优化橡胶缓冲块结构设计,并通过理论和试验验证优化设计的正确性。在满足使用要求的前提下,实现材料合理化利用,减轻橡胶缓冲块重量,从而达到降低整车成本,实现汽车轻量化的目的。     

吸能式汽车保险杠轻量化设计分析

在汽车保险杠原始结构的基础上,进行了轻量化设计.利用ANSYS/LS-DYNA软件对原始保险杠及其轻量化结构在低速碰撞过程中的动力响应特性进行了数值仿真,结果表明：原始保险杠在低速碰撞条件下应力分布不均匀,而加强筋保险杠和波浪加强板形保险杠耐撞性、能量吸收性更好,其应力分布较均匀,并且波浪加强板形保险杠性能优于加强筋保险杠.     

悬架参数多目标性能优化

以多体动力学理论为基础,利用机械动力学分析软件ADAMS建立某轿车的整车虚拟样机模型。研究悬架系统对乘员舒适性及车辆对道路破坏程度的影响规律。根据行驶平顺性和道路友好性各自评价指标进行了数值计算,分析了行驶车速、悬架弹簧刚度和减振器阻尼对车辆平顺性和道路友好性的影响,最后得到了优化的悬架参数。通过比较优化前后的车辆对道路的动载荷,提出了对车辆悬架设计与使用方面的有益建议。     

坡路对汽车道路友好性的影响

通过对道路友好性的阐述引出评价道路友好性的指标以及影响道路友好性的因素.利用ADAMS动力仿真软件在ADAMS/View模块下建立了整车模型,对整车模型进行动力仿真,对比分析坡路对道路友好性的影响.     

行人头部碰撞仿真及优化

人一车碰撞事故中行人的头部同汽车的碰撞往往是造成致命性伤害的关键因素,利用DYNA软件能较好地实现对碰撞过程的仿真,仿真精度能够满足要求并且再现性好。文中介绍了某款车型对头部碰撞的仿真,并对头部的伤害值进行评估,着重分析了造成致命伤害的主要原因,为新车的行人碰撞保护的研究和设计开发作参考。     

基于接触特征的车—人碰撞事故模型构建与分析

接触损伤和接触变形是交通事故遗留的重要信息,车—人碰撞事故数值再现通常采用标准体形的假人模型和基于椭球体简化的刚体汽车模型,导致车、人接触位置数值仿真结果与真实事故场景存在较大差异,同时,当车速较高时汽车与行人接触部位容易产生过度穿透等问题。以缩放技术为基础,提出基于事故中受害人6大部位体形特征的假人数值模型定制方法。通过材料等效刚度曲线对车身接触部位进行定义,模拟车、人真实接触状态。通过行人与车身等效接触模型的建立,可以提高仿真计算精度,实现计算精度和计算效率的平衡。将上述方法在一起典型的车—人碰撞事故案例中进行应用,仿真结果表明,所得到的事故再现结果精度高、可靠性好,能够满足车辆变形状态下车—人碰撞交通事故过程再现的要求,为交通事故数值再现中的接触问题研究提供了新的思路。     

基于车辆-行人碰撞颅脑伤防护的参数研究

研究了汽车行驶速度及前部结构各设计参数对行人颅脑损伤的影响，讨论了颅脑损伤防护的可行性措施。运用多刚体动力学软件Madymo建立了基于不同车型参数的汽车前部结构数学模型以及行人人体数学模型，进行了车辆-行人碰撞的计算机仿真，并对仿真结果进行了分析研究。研究表明，汽车行驶速度、发动机盖盖沿高度以及发动机盖和挡风玻璃的刚度等参数对行人颅脑损伤影响显著。     

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RADIOSS的复合材料发动机罩行人保护研究

为研究复合材料发动机罩对行人头部的保护性能,以某车型发动机罩为例,建立了行人头部撞击复合材料发动机罩的有限元模型.利用RADIOSS求解器开展头碰分析,并将各头碰撞击点的加速度-时间曲线和HIC值与铝质机罩结构进行对比.对比结果表明:使用复合材料的发动机罩理论上能够满足行人保护需求,同时整体质量相比铝质发动机罩会更轻,...     

船舶表面新型环保防污涂料研究进展

随着人们环保意识的不断提高,环保、广谱的新型防污涂料已经成为当前海洋防污领域的研究热点。概述生物污损的形成过程和污损机制,综述近年来新型环保防污涂料的研究进展,包括污损释放防污涂料、光催化防污材料和基于仿生策略衍生而出的天然防污剂、水凝胶防污涂层等;介绍抗菌肽的作用机制和改性表面的制备手段,指出该类防污材料具有广谱的抗菌活性和环境友好性,有望成为具有理想防污功能的新型海洋防污涂料;展望未来防污涂料的研究方向,旨在为发展高效、广谱、绿色的海洋防污涂料提供参考。