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.

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.

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.

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.

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。

面向汽车安全的中国体征50^(th)百分位男性乘员生物力学模型开发及验证

汽车安全领域的智能化和数字化发展都急需能代表真实人体特征的生物力学计算模型。本文以最新中国成年人人体尺寸标准为依据,开发具有自主知识产权的50^(th)百分位中国男性体征汽车乘员生物力学模型(TUST IBMs M50-O)。通过重构3组正面钝性冲击、5组侧面钝性冲击和3组整人滑车尸体及志愿者试验,模拟C-NCAP可变形移动壁障侧面碰撞试验,多角度、全方位验证所开发模型的有效性及应用价值。结果表明:11组重构试验数据均在相应的尸体及志愿者试验通道内,平均差异在10%左右,验证了模型的有效性。TUST IBMs M50-O与WorldSID 50^(th)假人模型在侧面碰撞中的运动趋势相同,但TUST IBMs M50-O模型上肢对胸部的挤压,使得胸椎T4和T12质心合成加速度峰值达到43.5g和47.3g,高于WorldSID 50th模型峰值38.5g和41.2g。同时,TUST IBMs M50-O模型也从应力应变角度评估人体组织层面的损伤风险。综上,TUST IBMs M50-O模型展现了类似真实人体的高生物逼真度,可用于组织层面的损伤机理研究,也可为智能汽车安全防护装置及智能高端装备领域产品研发、汽车虚拟测评提供可靠的计算工具和技术支撑。

客车侧面碰撞安全研究进展

为了完善并制定具有中国特征的客车侧面碰撞安全法规,首先,阐述了欧洲及美国的汽车侧面碰撞安全法规,并介绍了中国客车法规的现状,从碰撞形式、假人类型、碰撞速度、假人位置及评价指标等方面对比了欧洲和美国汽车侧面碰撞法规的差异性;其次,从碰撞实验的角度,在实车碰撞、台车实验及计算机模拟仿真实验等方面总结了目前国内外对大客车侧面碰撞安全的研究现状,并对计算机模拟仿真实验从强度、结构、刚度等方面进行阐述;最后,基于当前国内外大客车的碰撞安全研究现状,预测了提高客车被动安全的发展趋势,即虚拟测评技术、主被动安全一体化、碰撞相容性等。研究结果可以为我国推出客车侧面碰撞法规提供理论参考。

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.

局部破损下考虑摩擦的直齿轮系统多状态啮合-碰撞动态特性研究

局部破损是直齿轮常见的故障之一,影响齿轮传动的平稳、安全运行。轮齿碰撞不可忽略,揭示局部破损下齿轮系统啮合-碰撞动态特性对提高齿轮系统安全稳定运行尤为重要。基于齿轮啮合原理和能量耗散碰撞接触力模型,考虑齿背接触的瞬时性,建立局部破损下齿面啮合模型和齿背碰撞模型。根据齿轮副接触状态及受力环境,对局部破损下多状态啮合-碰撞行为进行分类,建立局部破损下渐开线直齿轮系统啮合-碰撞离散动力学模型,探讨局部破损对齿轮系统啮合刚度和载荷分配的影响特征。分析局部破损下接触力变化机理,定义Poincaré映射截面,研究载荷系数和啮合频率变化下系统混沌、分岔特性。研究发现,局部破损影响接触力单双齿啮合区域,降低齿轮局部承载能力;较大载荷抑制齿背碰撞,较小载荷诱发周期运动共存现象和齿背碰撞;较大和较小啮合频率诱发齿背碰撞;混沌运动和周期运动共存现象诱发齿背碰撞,局部破损影响多周期共存现象,加剧系统运动的复杂性。揭示主动轮局部破损下考虑能量耗散的齿轮系统动力学模型及非线性振动机理,探究齿背碰撞发生条件。研究成果为故障齿轮系统非线性动力学建模和分析提供了新的方法和思路。

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。

民机侧壁板抗鸟撞性能评估方法研究

【目的】抗鸟撞性能一直是飞机适航性的重要检验因素之一。为探究某民机机头侧壁板的抗鸟撞性能,采用铆钉失效占比评估法、能量法以及剩余承载力评估法这3种方法进行评估。【方法】通过PAM-CRASH软件模拟3种构型侧壁板的鸟撞情况,验证了数值模型的有效性,并基于3种试验件的鸟撞破坏情况对上述方法的可靠性进行评估。【结果】研究结果表明,铆钉失效占比越低表明结构的抗鸟撞性能越好;结构的铆钉吸能占比大小提升且蒙皮吸能占比大小降低时,结构的抗鸟撞性能得以提升;剩余承载力评估法能够定量化分析抗鸟撞性能,当损伤因子越低,其抗鸟撞性能越好。【结论】对侧壁板试验件抗鸟撞性能评估法的适用性与局限性进行总结,为后期民机的安全设计和研究开发提供有价值的参考。

力士乐回转液压系统的优化设计

针对大型矿用液压挖掘机回转机构启动冲击、制动停止瞬间加载总成反向旋转造成的回转机构断齿、断轴及力士乐A2FE回转液压马达油口连接板192中的补油单向阀损坏的故障现象,通过增设回转缓冲阀、压力变送器等液压元器件,优化回转传动系统的启制动特性,降低回转机构启制动时的冲击,延长其使用寿命。结果表明:相较于优化前的回转液压系统,在相同的齿侧间隙下,优化后的回转液压系统的回转减速机输出轴小齿轮启动至接触回转滚盘轮齿的时长由0.5 s延长至1 s,有效减小系统的启动冲击;制动停止瞬间,回转马达A、B口之间的最大压差由3.6 MPa降至2.0 MPa,抑制了制动摆尾现象,降低制动冲击,操纵舒适性显著提高;回转液压系统无故障工作时长由1000 h提高到5368 h。

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。

基于交叉熵方法的汽车侧面结构耐撞性优化设计

为提升某型电动汽车侧面碰撞结构的耐撞性,提出基于交叉熵的侧面结构优化设计方法。首先,构建整车侧面碰撞结构有限元模型,并依据仿真及试验数据对比,验证了有限元模型的有效性;其次,依据仿真分析结果,取侧面结构板厚作为设计变量并赋予约束条件,将车门侧面撞击侵入速度最小化作为目标函数,构建侧面结构耐撞性优化模型,并采用交叉熵优化算法对其进行求解;最后,对某型车侧面结构耐撞性开展优化设计,并对优化结果有效性进行验证。优化结果表明:车辆侧面撞击侵入速度最大优化率为32%,提升了车辆侧面结构的耐撞性能,该结论对于整车结构优化提升具有参考价值。

整车侧碰壁障性能分析与结构耐撞性设计

中国新车评价规程与汽车保险指数均推出了适合中国的侧面碰撞移动可变性壁障(SC-MDB)与中国先进的侧面碰撞移动可变形壁障(AC-MDB)。文章对比了新旧侧面碰撞壁障的结构特征、蜂窝铝参数与碰撞能量的差异,仿真分析了不同壁障蜂窝铝的受压变形,提供了侧碰壁障力学特性的参考。应用某车型的碰撞模型进行仿真,分析了不同壁障对车身侧面结构耐撞性设计的影响。针对新版SC-MDB与AC-MDB侧面碰撞工况引起整车B柱与前后车门侵入量加大的问题,通过完善车身座椅横梁的传力路径,加大门槛、B柱与车门防撞杆等结构的强度,降低了侧碰车体的侵入变形,提供了新版侧碰壁障工况的结构优化设计方法。仿真分析结果验证了优化方法的有效性,为同类车型的结构耐撞性设计提供了优化思路与参考。