Application of Hot Forming High Strength Steel Parts on Car Body in Side Impact

Lightweight structure is an important method to increase vehicle fuel efficiency. High strength steel is applied for replacing mild steel in automotive structures to decrease thickness of parts for lightweight. However, the lightweight structures must show the improved capability for structural rigidity and crash energy absorption. Advanced high strength steels are attractive materials to achieve higher strength for energy absorption and reduce weight of vehicles. Currently, many research works focus on component level axial crash testing and simulation of high strength steels. However, the effects of high strength steel parts to the impact of auto body are not considered. The goal of this research is to study the application of hot forming high strength steel（HFHSS） in order to evaluate the potential using in vehicle design for lightweight and passive safety. The performance of HFHSS is investigated by using both experimental and analytical techniques. In particular, the focus is on HFHSS which may have potential to enhance the passive safety for lightweight auto body. Automotive components made of HFHSS and general high strength steel（GHSS） are considered in this study. The material characterization of HFHSS is carried out through material experiments. The finite element method, in conjunction with the validated model is used to simulate the side impact of a car with GHSS and HFHSS parts according to China New Car Assessment Programme（C-NCAP） crash test. The deformation and acceleration characteristics of car body are analyzed and the injuries of an occupant are calculated. The results from the simulation analyses of HFHSS are compared with those of GHSS. The comparison indicates that the HFHSS parts on car body enhance the passive safety for the lightweight car body in side impact. Parts of HFHSS reduce weight of vehicle through thinner thickness offering higher strength of parts. Passive safety of lightweight car body is improved through reduction of crash deformation on car body by the application of HFHSS parts. The experiments and simulation are conducted to the HFHSS parts on auto body. The results demonstrate the feasibility of the application of HFHSS materials on automotive components for improved capability of passive safety and lightweight.

KEY TECHNIQUES OF MULTI-BODY MODELING OF OCCUPANT RESTRAINT SYSTEM OF VEHICLE SIDE IMPACT

Based on multi-body dynamics, the simulation models of auto-side structures and occupant＇s dynamic responses are set up, using the occupant injury simulation software MADYMO3D. These models include auto-body structure, impact barrier, seat and dummy. Definitions of multi-body and joints and dynamics properties of joints based on FE combination models, of model setup are introduced. Kelvin element of MADYMO is introduced to show the force action between non-adjoining rigid bodies, too. Then all examples of the methods mentioned are given. By the comparison of simulation and real test, the contract curves between simulation and real test for main structures and biology mechanics properties of dummy are obtained. The result shows the accuracy and validity of the models.

Numerical Study on Neck Injury Under Different Postures in Vehicle Side Impact

Neck injury is a severe problem in traffic accidents.While most studies are focused on the neck injury in rear and front impacts,few are conducted in side impact.This study focuses on the difference of neck injury under different postures and the difference of 7 cervical vertebras under the same posture using the method of prescribed structure motion（PSM）.The analytical results show that the maximum changes of mean force and mean moment of 7 cervical vertebras under 8 different postures are 20% and 47% respectively.The variation of each cervical vertebra is different under different neck postures.Up cervical vertebras （C1-C4） and low cervical vertebras （C5-C7） suffer different forces and moments under the same neck posture.Generally speaking,No.6 （neck right leaning 40°） is the posture with lowest neck injury risk.

Development of a Side Door Composite Impact Beam for the Automotive Industry

The automobile industry has been searching for vehicles that use less energy and emit fewer pollutants, which has resulted in a high demand for fuel-efficient vehicles. Because of their higher strength-to-weight ratio compared to traditional steel, using fiber-reinforcement composite materials in automobile bodies has emerged as the most effective strategy for improving fuel efficiency while maintaining safety standards. This research paper examined the utilization of fiber-reinforced composite materials in car bodies to meet the increasing consumer demand for fuel-efficient and eco-friendly vehicles. It particularly focused on a carbon-aramid fiber-reinforced composite impact beam for passenger car side door impact protection. Despite the encouraging prospects of the carbon-aramid fiber-reinforced beam, the research uncovered substantial defects in the fabrication process, resulting in diminished load-bearing capacity and energy absorption. As a result, the beam was un-successful in three-point bending tests. This was accomplished by using an I cross-section design with varying thickness because of the higher area moment of inertia. Vacuum-assisted resin transfer molding (VARTM) manufacturing process was used and the finished beam underwent to three-point bending tests.

Car Side Structure Crashworthiness in Pole and Moving Deformable Barrier Side Impacts

To clearly understand passenger car structure＇s crashworthiness in typical side impacts of pole and moving deformable barrier （MDB） impact modes, which could assist the establishment of Chinese vehicle side impact safety regulations, a full midsized car finite element model, calibrated by pole side impact test, was built and the p01e side impact according to European New Car Assessment Program （EuroNCAP） and the MDB side impact according to ECE R95 regulations were simulated with LS-DYNA. The accelerations and the structure deformations from simulations were compared. It can be concluded that the pole side impact focuses primarily on side structure crashworthiness as a result of large intrusions, while the MDB side impact focuses primarily on full side structure crashworthiness. Accordingly, occupant protection strategies focus on different aspects to improve side impact safety. In the pole side impact the objective is to maintain the passenger compartment and protect the passenger＇s head from impacting the pole, while in the MDB side impact the objective is to protect the full human body. In the design of the car side structures, at least these two tests should be considered for assessing their side impact crashworthiness. Conducting these two side impact tests as certified tests provides insights into car safety during side impacts.

侧面柱碰撞工况下Farside气囊对主驾WorldSID 50th假人损伤研究

在2023版Euro NCAP侧面柱碰撞试验中主驾和副驾均放置WorldSID 50th假人,为了研究Farside气囊对该工况下主驾假人的保护效果,选取某款车型分别在两种工况下进行实车碰撞试验,对驾驶员假人头部加速度、颈部力、右侧肩部力、右侧股骨力、右侧骶髂力等进行对比分析。

Side Structure Sensitivity to Passenger Car Crashworthiness During Pole Side Impact

Side impact accidents of passenger cars with fixed poles may result in severe injuries to the vehicle occupants. In this paper, side structure intrusion was considered as the criterion for passenger cars crashworthiness during side impact with a pole. The relationship between side intrusions and the side structure stiffness was analyzed. The acceleration of the unstruck side vehicle body was selected as the criterion for studying the influence of different side structure components on the side structure stiffness during passenger car pole side impacts. The behavior was analyzed using finite element simulations. The results show that the rocker and the lower part of the B-pillar are the key parts of the side structures in determining the passenger car side stiffness. Passenger car pole side impact crashworthiness is, therefore, most sensitive to these two components.

Innovative Electric Vehicle Body Design Based on Insurance Institute for Highway Safety Side Impact Conditions

A version of an electric vehicle was developed and designed for the US market on the basis of the required domestic body structure.When compared with the original car,the new car body design leads to two major technical difficulties.First,the installation of high-voltage components such as the battery pack and other new energy sources increases the vehicle weight and occupies a great deal of its structural space;this limits the impact paths and the use of traditional structural designs,which greatly increases the design difficulty.Second,the USA,as an advanced automobile-using country,has well-developed laws and regulations for collision standards,vehicle operating conditions and evaluation standards.Using a combination of butterfly diagram analysis,bending moment management,section forces and other computer-aided simulation and analysis techniques,this paper presents a body structure design that can achieve a“GOOD”evaluation under the US Insurance Institute for Highway Safety(IIHS)side impact body structure conditions by optimizing the force transfer path,the B-pillar deformation mode and the threshold support structure.The threshold support structure supports realization of the“GOOD”rating for IIHS side impact and helps the body to meet the crash requirements of the Federal Motor Vehicle Safety Standard FMVSS214 and the US New Car Assessment Program(NCAP)requirements for side impact at 32 km/h and 75°angular pole impact.

基于C-NCAP远端气囊建模仿真与试验对标

中国新车评价规程(Chinese new car assessment programme,C-NCAP)2024版乘员保护板块中新增了侧面碰撞远端乘员保护的虚拟测评项目,但是当前车辆的被动安全系统尚没有达到该评价规程要求.针对该现状,提出了在远端乘员侧添加远端气囊的解决方案,建立了远端气囊有限元模型,并进行了试验对标.首先,运用CATIA软件建立远端气囊的三维模型,利用HyperMesh对气囊模型进行几何清理及网格划分;其次,采用Primer软件折叠划分好网格的气囊有限元模型,设置远端气囊的材料属性及模型参数,应用LS-DYNA软件进行运算求解;最后,根据静态点爆与动态冲击试验结果对标远端气囊有限元模型.结果表明,静态点爆试验对标误差为1.4%,动态冲击试验对标误差在10%以内,符合新规要求.

侧面柱碰撞工况下安全气囊参数对乘员损伤的影响研究

为提高侧面柱碰撞工况下乘员的安全性,针对乘员在车速32 km/h侧面柱碰撞工况下的损伤进行了仿真分析。首先建立了侧面乘员约束系统模型并进行了可靠性验证,为改善侧面柱碰撞工况下安全气囊对乘员的保护效果,依据2021年版《C-NCAP管理规则》中侧面柱碰撞试验方法,搭建了车辆侧面柱碰撞规定结构运动(PSM)子结构模型,最后将试验与仿真结果进行对比,结果表明,合理的气囊形状、点火时刻及排气孔直径可有效提高乘员保护效果。

人工种植牙邻接触丧失应对策略的专家共识

人工种植牙邻接触丧失(proximal contact loss,PCL)所引发的问题是近年研究热点,学者们一致致力于其原因和相关因素分析,旨在寻求解决与PCL相关问题的方案。前驱力作用、颌骨及牙槽窝等终身改建以及种植牙的骨整合特性是PCL的主要原因。一方面,下颌的闭口运动通过后牙牙尖产生了将牙齿往近中移位的前驱力,使上下颌后牙、下颌前牙近中漂移,同时,可使上下颌前牙唇向移位;另一方面,颌骨、牙槽窝、牙根的改建以及咀嚼肌的前向水平分力、下颌向前向上的动力分量以及牙尖斜面产生的向前分力使天然牙向近中漂移;此外,天然牙终身具备水平、垂直向移位以及旋转的能力,以适应口颌系统的改建和维持口腔的功能,而种植牙骨整合缺乏天然的牙周膜,缺乏近中漂移生理基础,垂直向平均动度微小,种植牙骨整合沉默性不具备天然牙整体漂移特点,增加了PCL发生的可能性。PCL高发生率与戴牙时间和近中位置有明显相关性,但也受咬合力大小、对颌牙状况、邻牙情况、修复方式、牙位、上下颌骨、年龄、性别等因素影响。PCL与食物嵌塞呈显著相关性,但并不一一对应,不满足充分必要条件。PCL也与种植体周病变以及龋齿等有关。PCL的预防包括知情同意、定期检查、固位方式选择、接触点增强、配戴保持器以及应用多用途数字化牙冠。PCL的处理包括邻接触点增补、正畸牵引以及咬合调整。现有方法可以短期解决食物嵌塞情况,综合干预以寻求稳定的远期效果。对称、平衡的考量将拓展处理有关PCL引发的问题。

电动车侧面柱碰撞电池包性能优化

本文针对某电动车在侧面柱碰撞中出现的电池包内部电芯和冷却系统变形较大的问题,以及碰撞中存在漏液起火爆炸的风险进行了分析。针对这些问题,提出了相关的优化方案,并通过整车碰撞仿真分析进行了验证。优化后,整车的变形侵入明显降低,电池包内部电芯和冷却系统的变形侵入也得到了改善。电芯、冷却系统的受力分别从10.8 kN、9 kN降低到4.8 kN、3.5 kN,电芯和冷却系统基本无明显变形,电池包碰撞后的风险问题得到了改善。

侧面柱碰撞工况下动力电池结构安全研究

为提高侧面柱碰撞工况下纯电动汽车动力电池系统的安全性,建立了包含动力电池系统的侧面柱碰撞有限元模型,并利用整车侧面柱碰撞试验验证了有限元模型的准确性,以结构变形量和加速度冲击为评价指标,利用该模型分析了侧面刚性柱碰撞工况下的电池包变形状态和加速度响应,结果表明,侧面柱碰撞工况下,动力电池包外框架及内部支撑结构均发生较严重变形,电池系统各位置均承受较大加速度冲击。基于该结果,提出了在动力电池包和车身门槛梁结构设计时应面向该工况进行针对性安全设计的建议。

慈林山煤业沿空掘巷让压支护技术应用

为解决小煤柱沿空掘巷煤柱支承应力较大以及采空区顶板坚硬岩层断裂产生动载破坏围岩支护的问题,对慈林山煤矿15208工作面运输顺槽沿空掘巷支护存在的问题进行分析,开展单泡让压管和双泡让压管抗压试验,同时优化锚杆、锚索的施工。结果表明让压管能够提高锚索的延伸率,在压力显现时能够吸收围岩传递的能量,保证锚杆、锚索的有效性;在此基础上对帮锚索的优化能保证支护强度的同时还能提高生产效率并降低支护成本。

材料应变率模型对汽车B柱侧面碰撞影响分析

B柱侧碰过程是短时高速的材料吸能过程,材料的性能与静态时差异较大,因此采用静态性能参数进行B柱侧面碰撞仿真分析结果误差较大。针对B柱常用的相变诱发塑性钢(TRIP钢)进行不同应变速率下的力学拉伸试验,提取主要的性能参数,获取参数随应变速率的变化规律;对比材料的力学性能和成形性的变化趋势;基于Johnson-Cook简化模型,获取材料的应变速率敏感因素和应变率相关的材料本构模型,作为碰撞仿真分析的材料输入;与实际测试对标,建立B柱侧碰分析的仿真模型,将传统静态数据外延获取的本构模型与应变速率相关的本构模型作为输入,对比两种材料模型分析结果的差异,并与试验测试结果进行对比分析。结果可知:TRIP690的强度和断后延伸率受应变速率影响较大;基于修正Hollomon方程,材料的瞬时加工硬化基本不受应变速率变化的影响;基于Johnson-Cook模型,获取材料的应变速率敏感性参数为0.00805,数值偏低,表现出此种材料对应变速率变化敏感性比较差;材料应变速率相关本构模型可有效提升B柱侧碰分析结果的准确性,与试验结果的分析误差控制在3%以内;而采用静态特性参数外延的分析结果误差则超过9%。研究内容和结果为此类研究提供参考。

侧面碰撞远端老年乘员损伤研究

为探究欧洲新车评价规程(Euro-NCAP)侧面碰撞条件下远端老年乘员的运动学响应和损伤机理,首先利用老年人体模型CHARM-70建立台车模型,然后建立整车AE-MDB侧面碰撞和侧面斜柱碰撞有限元模型,进行整车碰撞仿真并提取非碰撞侧B柱底部加速度脉冲,最后,基于THUMS_AM50_V4.0人体模型和老年人体模型CHARM-70建立单乘员和双乘员台车仿真模型,进行AE-MDB侧面碰撞和侧面斜柱碰撞仿真。结果表明:在侧面碰撞中,安全带无法有效限制远端乘员因惯性而导致的侧向偏移;在单乘员台车仿真中,远端老年乘员头部和颈部损伤值远小于阈值,但胸部出现大面积严重肋骨骨折;在双乘员台车仿真中,远端老年乘员的头部和胸部出现严重损伤。

一种侧面碰撞用蜂窝铝壁障性能开发与验证

以SUV车型为研究对象,开展了中国特征侧面壁障开发。通过对典型SUV车型特征进行参数提取,定义蜂窝铝壁障及台车的开发目标,运用特雷斯卡(Tresca)理论模型指导壁障材料选型与台车部件规格确定。通过壁障台车动态测力墙试验对蜂窝铝壁障的性能进行了改进与验证。结果表明:改进后壁障变形模式稳定,力学性能满足设计规范,能够表征SUV车型的外观和刚度特征。

冲击反作用式炮口制退器数值模拟分析

针对冲击反作用式炮口制退器炮口流场建立数学物理模型,进行数值模拟仿真计算,采用多种控制方程及k-ε模型,并利用动网格技术,计算得到了炮口流场的结构和流动参数。通过单冲击式炮口制退器与冲击反作用式炮口制退器壁面合力,炮膛合力等对比,揭示了该型制退器炮口流场的发展规律,且展示了其相比于冲击式炮口制退器的优势。冲击反作用式炮口制退器在发射时后排边孔道出口截面压力明显高于前排的边孔道出口截面压力,与冲击式炮口制退器相比,炮膛合力不足其1/3,制退器壁面合力不足其1/4。数值模拟结果可为该型制退器结构设计与优化提供必要的参考。

实车侧面柱碰撞Q3假人的损伤研究

针对目前国内标准缺乏对Q3假人在实车侧面柱碰撞工况下的测试和评价,开展了9个实车侧面柱碰撞试验,将Q3假人放置在驾驶员后排座椅。结果显示,头部3ms累积合成加速度只有1次试验没有扣分,有2次超出低性能值;HIC15有4次出现扣分,1次超出低性能值;胸部3ms累积合成加速度只有1次小于低性能值;骨盆合成加速度峰值大。颈部的受伤风险小。Q3假人的头部、胸部和腹部有较大受伤的风险,应纳入评价指标。

基于激光拼焊技术车身B柱轻量化设计分析

B柱是侧面碰撞的关键承载结构件,对整车安全性具有重要影响。基于B柱可制造性工艺分析模型,对B柱进行成形工艺分析;在保证成形工艺的前提下,对B柱进行激光拼焊设计;对拼焊的材料和厚度进行分析;在此基础上,对激光拼焊的焊缝位置进行设计;基于整车侧碰安全性分析模型,对获得的拼焊设计方案进行碰撞安全性分析,对比优化设计前后的侵入量和侵入速度;依靠激光拼焊方案量产车型,对激光拼焊B柱的轻量化效果和安全性进行分析,并对设计过程的可靠性进行验证。结果可知:B柱零件的上部选用DP780,下部采用DP590,且上下的板厚差不超过0.6mm,可以满足激光拼焊成形要求,焊缝的位置距离B柱低端370mm时,减薄率最低为21.1%;激光拼焊设计与原设计安全性基本保持一致,各测点指标的误差小于3%;原设计方案B柱的总量为21.3kg,而激光拼焊方案B柱的总量为17.5kg,轻量化减重达到21.7%;激光拼焊方案实测结果满足碰撞要求,侵入量最大值为137.8mm,侵入速度的最大值为4.33mm,均小于最大限值;仿真分析和实测各个测点的结果保持基本一致,侵入量的最大误差为5%,而侵入速度的最大误差为5.4%,表明模型仿真分析结果的可靠性,为此类设计提供参考。