儿童乘员约束系统台车碰撞试验设计与研究

为满足GB 27887-2011规定的儿童乘员用约束系统动态性能试验的台车加速度区间要求,提出组合不同长度、壁厚、直径的圆形薄壁吸能管来实现台车碰撞试验波形的方法。采用LS-DYNA软件建立台车和吸能管的有限元模型,并通过该模型获得能复现法规要求的前后碰撞加速度区间的吸能管组合参数,经台车碰撞试验验证其有效性和精确性。对碰撞过程中Q6儿童假人头部和胸部动态响应进行了致伤机理分析,同时基于像素分析法提取了假人头部质心位置的运动轨迹,最后通过分析试验结果,对该新型儿童约束系统提出了改进意见。     

利用Radioss进行某车型侧面碰撞仿真和优化

建立了基于Radioss的某车型侧面碰撞有限元模型,依C-NCAP 2012版中的时速50 km可变形移动壁障侧面碰撞试验条件设定仿真的载荷和边界条件,计算相关位置的加速度、侵入速度、侵入量,与事先设定的五星车目标值进行比较,通过优化结构设计,使不达标项达标。通过在模型中加入有限元侧面碰撞假人模型,依C-NCAP 2012版计算假人相关位置伤害值,仿真结果表明该车侧面碰撞达到五星车要求。     

基于模块化设计的正面碰撞车身加速度复现技术研究

基于模块化设计概念,研究了微型汽车车身加速度波形复现技术。论文对微型汽车平台衍生车型的正面碰撞车身加速度波形进行了等效简化,分析了关键结构吸能特性对车身加速度波形的影响;基于能量吸收和刚度等效,设计等效结构台车替代平台衍生车型研发过程中的骡子车,通过车身加速度波形验证试验表明台车设计方法可实现车身加速度的复现,该台车所测车身加速度波形满足乘员伤害相应模型仿真输入要求,有效提高了研发效率并降低了设计成本。     

客车与乘用车侧面碰撞试验相容性实例分析

为研究汽车碰撞的相容性情况,采集并分析了乘用车车身非碰撞侧加速度值和客车侧面碰撞试验台车质心加速度值,对比分析了乘用车与客车侧面碰撞试验后蜂窝率的变形情况。经过分析得出乘用车与客车的碰撞相容性较差。在道路上行驶时,应避免与质量相差较大的汽车发生碰撞,以保证自身的生命财产安全。     

正面台车碰撞试验标定试验评价准则研究

为研究正面台车标定试验评价准则,分析正面碰撞试验中驾驶员侧假人头部x向外力作用加速度a_(xh)和胸部z向加速度a_(zc),指出a_(xh)和a_(zc)全面反映了转向机构、安全气囊、安全带的作用效果,积分得到的对应速度v_(zc)和v_(xh)可以作为评价准则基础。通过对当前台车试验中存在的问题进行探讨,对编号T006的台车标定试验结果进行研究,得出台车标定试验评价准则:在假人头部回弹之前,v′_(xh)处于所复现实车的v_(xh)±1 m/s范围内;假人胸部运动在C阶段之前,v′_(zc)处于v_(zc)±0.22 m/s范围内时,台车标定结果满足要求。该准则对仿真对标也具有指导意义。     

基于AEMDB试验的不同假人损伤性能研究

2015版欧洲新车评价规程(Euro NCAP)侧碰和侧面柱碰试验中,将WorldSID 50th代替ES2假人进行评价新车的被动安全性能。为了研究WorldSID 50th假人和ES2假人的不同响应特性,提出了假人损伤百分比的概念,并对两种假人进行了假人部件位置的对应关系,随后进行了某个车型2次实车侧面碰撞试验进行对比分析,所有试验设置均是按照Euro NCAP侧碰试验要求进行的。结果表明:在车门侵入速率一致的前提下中,ES2假人的头部、胸部和腹部比WorldSID50th假人的损伤值要高,ES2假人骨盆损伤值要比WorldSID 50th假人低。     

基于MADYMO模型的再次优化使达到 C-NCAP 4星的目标

为了达到某车C-NCAP 4星的目标,在基于台车试验数据、几何数据和约束系统零部件试验数据的基础上,建立了某车正面100%碰撞乘员约束系统的MADYMO模型,此模型可以很好的再现滑台试验,并在改变气囊和安全带参数上进行了优化,优化后假人伤害值达到了预期的分解目标,做滑台试验验证了MADYMO模型的准确性,第一次摸底试验副驾驶员侧假人头部及颈部伤害值未达到预期的分解目标。再次通过MADYMO优化副驾驶员侧气体发生器向安全气囊充气的性能(压力-时间曲线),使副驾驶员侧假人头部及颈部伤害值达到满分,第二次摸底试验结果达到了假人伤害值的分解目标。     

DAB开发和检验中线性冲击试验应用研究

<正>面碰撞试验中,利用假人头部加速度与颈部约束力间的关系,提取出安全气囊作用下假人头部x向加速度,并通过积分加速度得到安全气囊对头部x向的降速,进而推导出安全气囊x向所吸收碰撞能量。线性冲击试验中安全气囊对冲击头吸能过程与正面碰撞试验中x向安全气囊吸能过程表现一致,能够很好反映安全气囊对头部的保护作用。研究指出,在基础碰撞试验前,可以通过线性冲击试验确认及优化驾驶员侧安全气囊(DAB);在DAB开发过程中,线性冲击试验可以取代大量台车试验检验DAB的保护性能。同时也指出,在DAB检验过程中,线性冲击试验可以取代静态展开试验和压力容器试验,进一步增强对DAB保护性能的检测。     

基于侧面碰撞壁障的机械假人损伤分布研究

随着汽车工业的迅速发展,汽车碰撞安全问题也越来越受到人们重视。当发生交通事故侧碰撞时,被撞车内留给乘员生存空间较小,因此研究如何减少碰撞中人员受到的损伤成为侧面碰撞研究的核心之一。通过使用简化台车边界设置,模拟侧面碰撞载荷环境,利用机械假人进行侧面碰撞过程的乘员损伤分布分析,研究假人头部、脊柱、肋骨等部位的加速度及受力情况来量化分析被撞侧乘员在不同坐姿状态下头部及躯干的损伤分布特征及分布差异。研究结果表明,乘员向右侧旋转的坐姿状态下,头及躯干各部位的损伤输出结果较小,这些部位损伤相对其他坐姿较低,锁骨处在碰撞中损伤最大。研究结论为汽车侧碰撞安全中的乘员防护相关研究中乘员坐姿与损伤风险研究提供参考。     

基于实车正面碰撞试验Q3假人头部伤害仿真分析

通过分析某实车碰撞试验数据,基于LS-DYNA分析软件对实车进行对标后,优化分析Q3儿童假人的头部伤害情况,并阐述了后向安装儿童座椅在整车碰撞中的表现缺陷.结果表明:在正面碰撞试验工况中,后向安装形式的儿童座椅上布置Q3假人,受儿童座椅本身骨架强度、后排座椅整体支撑刚度、前排座椅靠背结构及空间位置的影响,Q3假人伤害比...     

碰撞仿真用壁障的模型标定

碰撞仿真用台车及壁障模型精度对仿真分析结果影响很大，为确保分析结果的准确性，针对C-NCAP 管理规则（2012年版）中新规，使用专业碰撞分析软件完成对正面偏置碰撞壁障和侧面碰撞台车壁障的标定。结果显示正面偏置碰撞壁障和侧面碰撞台车壁障满足新法规的分析精度要求。     

The harp: a vehicle crash test apparatus for full-scale crash test experiments

The current paper describes an apparatus for full-scale vehicle crash test experimentation. This apparatus is referred to as the harp. In brief, the harp may either accelerate a trolley which is impacted into a test vehicle or the test vehicle itself may be accelerated and impacted into an object such as a barrier, a pole, or another vehicle. If a trolley is accelerated, it is equipped with load cells to record the axial crushing force. If a test vehicle is accelerated, it is equipped with a three-axis accelerometer to record the crushing force. At the impact site, high-speed cameras and instrumentation record vital data during the crash.     

铝制车身仿真方法研究及试验对标分析

基于某MPV车型进行铝制车身碰撞安全仿真方法的研究,应用内聚力材料模型模拟胶粘连接和应用Constrained_SPR2模型模拟自穿刺铆钉,并与正面碰撞试验结果进行对标,从车身关键零部件变形模式、B柱下部加速度曲线和其他试验数据等方面进行了对比分析。结果表明:正面碰撞仿真结果与试验高度吻合,内聚力材料模型和Constrained_SPR2模型能分别有效模拟胶粘和铆接连接区域实际碰撞情况。     

轿车正面碰撞有限元仿真研究

在碰撞仿真理论的指导下,根据国家C-NCAP的规定,以某型号轿车为研究对象,利用有限元软件ANSYS/LS-DYNA建立整车正面碰撞有限元模型,对整车正面碰撞进行仿真分析。通过对整车以及前部钣金部件和前门框变形和加速度时间历程曲线的研究,评价整车的安全性,结合有关文献的研究,分析正面碰撞建模方法的正确性。     

不同侧碰试验形态的车辆结构耐撞性研究

基于侧面碰撞对乘员伤害的严重性,应用计算机仿真方法开展轿车侧面碰撞研究,通过对车身侧面结构变形、能量响应、加速度响应、乘员逃生空间等方面的深入分析,揭示不同侧面碰撞形态的碰撞特性,并据此提出了相应的改进措施。结果表明:与车对车侧面碰撞相比,车对障碍物侧面碰撞增大了对乘员造成更严重的损伤的风险,对车身的耐撞性提出了更高的要求,通过提高门槛梁、地板横梁强度可以有效的提高车辆抗柱撞的车身结构安全性。     

基于有限元法的电动汽车车身正面碰撞仿真及拓扑优化

车辆正面碰撞的安全性是汽车被动安全性研究的重要方面。利用有限元法对电动汽车碰撞进行了研究,借助LS-DYNA分析了驾驶室最大加速度变化情况和车辆前舱的能量吸收情况,在此基础上,对车身进行了拓扑优化设计,依据优化结果对车身结构进行了改进。通过计算机仿真,分析了汽车的被动安全性,对下一步实车碰撞试验有极大的指导意义。     

Modeling of friction-stir butt-welds and its application in automotive bumper impact performance Part 1. Thermo-mechanical weld process modeling

The demand for better structural performance in joining of components for road vehicles prompts the implementation of aluminum alloy friction stir welding technology in the automotive industry. The aim of current study is the creation of a 3-D finite element (FE) friction thermal model and stir welding (FSW) process of dissimilar aluminum alloy and for the estimation of crash worthiness performance of FSW fabricated shock absorber assembly. Thermo mechanical simulations and analysis are performed to understand the thermal behavior in the FSW weld zones. The developed models are correlated against published experimental results in terms of temperature profile of the weld zone. The developed models are then implemented for fabricating vehicle bumper parts to illustrate the performance of FSW welded components during an impact. Customary sled testing for low-speed guard necessities is performed utilizing a grating blend welded test apparatus at Wichita State University (WSU) at the National Institute for Aviation Research (NIAR). A few guard congregations are then appended to the test installation utilizing FSW and conventional Gas bend GMAW welding strategies. Numerical models are likewise created where limited component investigation is utilized to contrast the anticipated harm and the real harm maintained by both of the FSW and GMAW manufactured guards. During the research, a new FSW weld mold is created that allows for a better representation of the desired progressive crack propagation. The FSW fabricated bumper based on the Johnson-Cook failure model yields better failure prediction and is in good agreement to the test. The results from this study provide a guideline for an accurate finite element modeling of a FSW fabricated components and their application in the crashworthiness of such structural components.     

Design and optimization for the occupant restraint system of vehicle based on a single freedom model

Throughout the vehicle crash event, the interactions between vehicle, occupant, restraint system (VOR) are complicated and highly non-linear. CAE and physical tests are the most widely used in vehicle passive safety development, but they can only be done with the detailed 3D model or physical samples. Often some design errors and imperfections are difficult to correct at that time, and a large amount of time will be needed. A restraint system concept design approach which based on single-degree-of-freedom occupant-vehicle model (SDOF) is proposed in this paper. The interactions between the restraint system parameters and the occupant responses in a crash are studied from the view of mechanics and energy. The discrete input and the iterative algorithm method are applied to the SDOF model to get the occupant responses quickly for arbitrary excitations (impact pulse) by MATLAB. By studying the relationships between the ridedown efficiency, the restraint stiffness, and the occupant response, the design principle of the restraint stiffness aiming to reduce occupant injury level during conceptual design is represented. Higher ridedown efficiency means more occupant energy absorbed by the vehicle, but the research result shows that higher ridedown efficiency does not mean lower occupant injury level. A proper restraint system design principle depends on two aspects. On one hand,the restraint system should lead to as high ridedown efficiency as possible, and at the same time, the restraint system should maximize use of the survival space to reduce the occupant deceleration level. As an example, an optimization of a passenger vehicle restraint system is designed by the concept design method above, and the final results are validated by MADYMO, which is the most widely used software in restraint system design, and the sled test. Consequently, a guideline and method for the occupant restraint system concept design is established in this paper.     

The effect of crash pulse on occupant injury in frontal coach collisions

The purpose of this study is to reveal the effect of different acceleration curves on occupant injury risk in the frontal collision of coaches. Based on characteristics of frontal crash acceleration curves, the influence of characteristic parameters on occupant injury was studied using a two-factor variance analysis method. The finite element-rigid body coupling method was used to establish a coupled simulation for the dummy and the sled and evaluate differences in the effects on occupant injury between the acceleration curves of four different coaches and the acceleration envelope of the ECE R80 standard. Results indicate that the upper limit of the simplified curve has the greatest influence on occupant injury and it displays a positive correlation. The acceleration curve stipulated by ECE R80 is too idealized, which may lead to inadequacies in safety protection capability in vehicle and seat design.