MPDB工况下碰撞兼容性的基本问题与车体设计原则

2021版中国新车评价规程(C-NCAP)首次引入了正面50％重叠可渐近变形移动壁障碰撞工况(MPDB)用于评价车辆的碰撞兼容性.为了提高试验车在MPDB工况中的碰撞兼容性表现,得到影响碰撞兼容性的关键车体结构和基本的结构设计原则,应用对碰理论分析MPDB工况的2个基本物理问题——壁障与车体的吸能关系和运动变形关系.基...     

新型点阵夹层防撞梁与负泊松比吸能盒复合总成开发与吸能性能

为高效解决车身结构抗撞性和轻量化同步实现的难题，以乘用车前防撞梁与吸能盒为例，将点阵夹层结构与负泊松比结构用于其设计，并考察新型复合总成的吸能性能。以传统高强钢方案作为对标基准，获取待开发总成的性能设计依据。基于高强钢总成40%重合率碰撞试验，完成有限元模型的精度验证，进而获得全宽碰撞的结构响应特征及吸能参考数值，用于指导新型总成的开发。通过数值模拟算例，分析新型复合总成对冲击输入能量的适应性及吸能量对负泊松比吸能盒壁厚的敏感性，从而提出增加吸能盒封板与防撞梁支撑的改进方案。改进后的点阵夹层防撞梁具有更佳的承载刚度与载荷传递能力，总成变形模式愈加合理；改进前、改进方案1与改进方案2的总成吸能量分别占输入总能量的11.5%、68.2%与92.76%，高于高强钢方案的64.09%；改进方案2较高强钢方案减重32.9%。复合前防撞总成的台车试验与仿真结果对比显示：输入能量、碰撞初速度、总成吸能量、平均压溃量、平均碰撞力与回弹速度等指标的偏差绝对值均小于5%。结果表明：采用点阵夹层结构与负泊松比结构后，新型复合总成的吸能性能与轻量化水平均优于高强钢方案，2类结构适合于车辆承载与吸能结构，复合总成的设计方法与开发流程适用于相关新型结构的开发。     

Crash analysis and dynamical behaviour of light road and rail vehicles

The main goal of crashworthiness is to ensure that vehicles are safer for occupants, cargo and other road or rail users. The crash analysis of vehicles involves structural impact and occupant biomechanics. The traditional approaches to crashworthiness not only do not take into account the full vehicle dynamics, but also uncouple the structural impact and the occupant biomechanics in the crash study. The most common strategy is to obtain an acceleration pulse from a vehicle structural impact analysis or experimental test, very often without taking into account the effect of suspensions in its dynamics, and afterwards feed this pulse into a rigid occupant compartment that contains models of passengers. Multibody dynamics is the most common methodology to build and analyse vehicle models for occupant biomechanics, vehicle dynamics and, with ever increasing popularity, structural crash analysis. In this work, the aspects of multibody modelling relevant to road and rail vehicles and to occupant biomechanical modelling are revised. Afterwards, it is shown how multibody models of vehicles and occupants are used in crash analysis. The more traditional aspects of vehicle dynamics are then introduced in the vehicle models in order to appraise their importance in the treatment of certain types of impact scenarios for which the crash outcome is sensitive to the relative orientation and alignment between vehicles. Through applications to the crashworthiness of road and of rail vehicles, selected problems are discussed and the need for coupled models of vehicle structures, suspension subsystems and occupants is emphasized.     

车身碰撞仿真技术在红旗轿车车身开发中的应用

汽车被动安全国内研究大多集中在实车检测方面。本文介绍了红旗轿车车身开发中应用高度非线性有限元方法对车身结构碰撞历程进行数值仿真研究工作的概况。通过对基本结构件的研究弄清计算方法和参数,通过对车身主要吸能结构元件仿真计算研究,找出合理的技术参数,为全车身碰撞计算提供依据。在这些工作基础上成功地进行了红旗轿车车身碰撞计算。与实车碰撞实验结果相比,吻合较好,对红旗轿车前纵梁组件不同设计结构方案能量吸收性     

汽车结构耐撞性设计与优化研究综述

汽车的碰撞安全问题是汽车行业一直重点关注的问题之一,开展汽车结构的耐撞性设计已成为提升车辆碰撞安全性的重要手段。文章对国内外汽车结构耐撞性设计与优化的研究成果进行回顾与总结,鉴于碰撞过程的强非线性与众多设计准则相互耦合等特性,重点对近似多目标耐撞性优化方法及其应用进行综述,并分析存在的问题和进一步深入研究的方向。     

车用结构胶有限元模型方法的分析与比较

随着车用结构胶技术的进步,其性能不仅可以满足大量新型复合材料的连接工艺要求,而且可以弥补在汽车碰撞过程中点焊连接工艺应力集中的缺陷,因此开展对车用结构胶的研究十分必要。文章从有限元方法分析的角度,在总结国内外有关结构胶有限元模型的前提下,综合模型的理论基础、模型计算时间、模型仿真结果与试验的比较等因素,评价各模型特点,结合整车碰撞有限元模拟的要求,论证得出一维模型方法更适用于整车碰撞模拟。     

电缆扰动对传感器信号的影响

通过实验介绍了整车在碰撞过程中传感器电缆线的动态性能对信号的影响,特别是在高速整车碰撞工况下电缆线产生的干扰信号。通过冲击台模拟整车碰撞过程中电缆信号的震动,分别采用有效固定电缆线和不固定电缆线两种方式进行冲击,得出只有有效的固定好电缆线才能保证信号的有效性和正确性。     

汽车碰撞安全与轻量化研发中的若干挑战性课题

汽车结构与动力电池的碰撞安全性是开发轻量化、电动化汽车的强制性要求和关键基础性支撑技术。通过3个方面的10个典型课题及研究结果,介绍并综述了汽车碰撞安全性研发的技术挑战。第一,采用夹层式汽车前舱罩盖技术,提升罩盖结构力学特性的横向均匀性以及冲击响应历程的均匀性,满足汽车吸能位移限定下的行人头部碰撞响应控制;采用精细人体有限元模型解析复杂工况下行人下肢损伤机理和影响参数,基于人体组织损伤层面的虚拟评估改进汽车结构的人体碰撞保护设计;面向复杂道路交通事故工况和多样化人体特征,解决强非线性条件下的自适应乘员智能保护系统优化设计难题,通过在时间和空间上对乘员约束载荷的均衡化实现针对工况可调的碰撞保护。第二,揭示材料冲击测试中系统共振导致信号振荡和材料屈服放大振荡的机理,开发抑制信号振荡的轻质动态力传感器;精细表征材料在碰撞载荷和复杂应力状态下的力学行为,针对高强钢、塑料、胶粘和焊点等轻质高强材料及复合连接接头建立大变形失效断裂预报方法及仿真模型。第三,基于动力电池多工况挤压试验,建立电池在外载荷作用下的材料失效、电压陡降与温度上升的响应特征关联性,提出用力学响应特征预测电池内部损伤起始和短路发生的判据,解决电池在机械滥用载荷下的短路预测问题,建立能准确预测电池变形响应的数值模型及碰撞安全评估方法,并应用于电池包和电动车的轻量化与碰撞安全性设计。     

Development and validation of side-impact crash and sled testing finite-element models

Side-impact collisions are the second leading cause of death and injury in the traffic accidents after frontal crashes. Side-impact airbags, side door bars and other protection techniques have been developed to provide occupant protection. To confirm the effectiveness of protection equipment installed in vehicles, studying the degree of impact is fundamental to understand the effect of automobile collisions on the human body. Therefore, the dynamic response of the human body to traffic accidents should be analyzed to reduce the level of occupant injuries. Generally, the experimental method is complex and expensive. Recently, numerical crash simulations have provided a valuable tool for automotive engineers. This work presents full-scale and sled side-impact test finite-element (FE) models - based on the Federal Motor Vehicle Safety Standard No. 214 - that simulate a side-impact accident. The crash simulations utilized the LS-DYNA finite-element code. The human body's dynamic response to crashes is discussed herein. Additionally, occupant injuries were measured. To verify the accuracy of the proposed crash test and sled test FE models, simulation results are compared with those obtained from experimental tests. The comparison results indicate that the proposed crash test and sled test FE models have considerable potential for assessing a vehicle's crash safety performance and assisting future development of safety technologies.     

汽车侧面碰撞移动变形壁障试验方法

移动变形壁障是实车侧面碰撞试验时用来撞击试验车辆的标准试验工具，移动变形壁障前部的吸能块可采用不同的材料和结构，其性能对试验结果起主要影响，因此必须对吸能块及检验方法作相应规定，以保证试验结果的一致性，介绍了国外对移动变形壁吸能块性能进行考核的各种试验方法和评价要求，这些试验方法能够为我们进行侧面碰撞移动壁障的设计制造及检验提供参考。     

插电式混合动力汽车碰撞安全性能设计开发

在对插电式混合动力汽车的发动机、燃油箱和动力电池、电机、高压电路等关键零部件进行相关的碰撞安全性能开发时,不仅需要考虑传统燃油车的碰撞安全标准要求,同时还要考虑电动汽车动力电池安全相关的碰撞标准要求和电安全设计防护。文章首先分析了相应的碰撞试验法规,结合上汽某插电式混合动力汽车整车布置方案,针对其特殊结构重点研究其追尾碰撞和侧面柱碰撞工况,在考虑传统汽车结构和乘员安全的基础上,对动力电池、高压电系统等电安全进行了分析。文章对研究插电式混合动力汽车的碰撞安全,具有一定的指导意义。     

车体“刚度”在正面碰撞中对人体伤害影响的研究

将汽车B柱加速度曲线反映的车体碰撞性能定义为车体"刚度",对车体"刚度"在实车碰撞中对假人伤害的传递过程及台车试验中复现的精度对假人伤害结果的影响进行了研究.通过对"刚度"在正面碰撞试验中对假人运动的影响分析和对骨盆受力情况的分析,指出了试验中假人对车体的相对加速度曲线是一近似正弦波.同时,进行了车体"刚度"曲线在台车试验中的应用研究,指出了在台车试验中应复现的最佳曲线及校核方法.     

Design optimization of thin-walled circular tubular structures with graded thickness under later impact loading

In order to improve the crashing performance under lateral impact scenario, a thin-walled circular tube with functionally graded thickness (FGT) is introduced with its superior performance in this paper. The wall thickness of the FGT tubual structure is graded along the axial direction. Based on the assumed graded thickness function, several important parameters (such as the graded exponent, the tube diameter and yield stress) are selected and their effects on dynamic energy absorption characteristics are discussed. The analyzed results show that the FGT has better crashworthiness in special energy absorption (SEA) and crash force efficiency (CFE) than uniform thickness (UT) tube. Then, the optimization design is further employed to obtain the Pareto fronts of the graded configuration under lateral impact loading. Note that the specific energy absorption (SEA) and crashing force efficiency (CFE) are regarded as the objectives, and the grading exponent, yield stress and diameter are defined as the design variables. The surrogate model with the best accuracy is chosen by error analysis for improving the accuracy of optimization process. Thus, the optimal solution is reasonably obtained and analyzed. The optimal results indicate that the FGT structures have significant potential applications into vehicle body especially under later impacting event.     

从道路交通事故研究看我国汽车正面碰撞法规试验形式

基于我国道路交通深度事故调查中所得数据,从碰撞位置与重叠率、碰撞速度和人员伤亡等方面,分析100%重叠率刚性固定壁障碰撞试验和40%重叠率偏置可变形壁障碰撞试验与我国交通事故形态和人员伤害与特征的关联度.讨论现有正面碰撞法规的试验形式的局限性,并论证了将偏置正面碰撞推荐性标准纳入我国正面碰撞强制性标准体系的必要性和紧迫性.     

Fracture properties of aluminum foam crash box

This study investigates the compression property experiment to examine impact absorption when aluminum foam is applied to crash box in order to absorb impact energy in car crash with low speed. The result of compression property experiment shows that case 6, which involves the buckling that collapses into 5-layer structure, is the best model with regard to impact absorption. This study analyzes impact characteristics according to the structure of crash box which influences such factors as damage and safety of vehicles. As the simulation result can be agreed with experimental graph, all experimental data at this study are verified. These experimental results can be applied into real field effectively. It also proposes the effective design to improve impact performance by analyzing the property of crash box through its compressive test.     

基于Benchmark技术的汽车正面碰撞仿真建模

介绍Benchmark的工作流程;根据某车型Benchmark数据,采用有限元分析方法,建立包括车身结构、发动机和底盘结构的用于正面碰撞的整车有限元模型;根据实验结果验证模型的有效性。     

混合动力轿车后碰安全性研究

针对某自主品牌混合动力轿车开发项目,利用有限元仿真分析和整车碰撞试验验证相结合的方法,研究了其高速后碰过程中燃油系统的完整性及高压电安全防护。通过合理的后舱结构设计以及软硬件双重高压防护的方案,使该轿车顺利通过高压电车辆国家后碰安全性法规。     

新型汽车碰撞能量吸收器

提出一种新型汽车碰撞吸收器,该装置具有机械的、剪切型的吸能方式。文中给出了该吸收器的结构和工作原理,对吸收器特性进行了台架与台车碰撞试验。试验结果表明:该吸收器能分解一次性碰撞的巨大能量,逐渐减小碰撞力并逐渐吸收其能量;降低人体所承受的减速度值及减少发生二次碰撞的概率。     

基于RCAR试验的汽车低速碰撞性能设计

介绍了RCAR低速碰撞试验与评价方法,RCAR碰撞结果对车辆保险费用的影响以及车辆低速碰撞性能设计的思路和方法,并以长城某轿车为例,利用仿真方法,从碰撞能量计算、吸能弹簧单元和吸能盒结构设计等方面具体阐述了车辆低速碰撞性能设计过程.     

电动汽车正面碰撞试验技术研究与分析

针对电动汽车结构特点和特性,总结和分析了国内外电动汽车正面碰撞试验相对应的电安全法规和标准,提出了电动汽车正面碰撞试验程序和评价方法。进行了电动汽车的实车正面碰撞试验,验证了试验程序和评价方法,比较和分析了原型车和电动汽车的碰撞试验结果,揭示电动汽车在正面碰撞形式下的碰撞特性,以及现行安全标准中存在的问题。