乘用车前挡风玻璃角度对行人头部/颅脑损伤影响研究

头部/颅脑损伤在车辆与行人碰撞事故中频繁发生,而行人头部与挡风玻璃的碰撞是导致头部损伤的主要原因。旨在采用数值模拟方法研究乘用车挡风玻璃倾斜角度对行人头部/颅脑损伤的影响。采用TNO多刚体行人模型和THUMS4.0头颈部有限元模型耦合得到新的行人碰撞数值模型,并结合已有的多刚体乘用车模型,借助真实的行人碰撞交通事故案例对该耦合模型进行基于人车动力学响应的有效性验证。在此基础上,构建人车碰撞模型矩阵,其中挡风玻璃角度的变化范围设定为24°~50°(间隔为2°),车辆速度设置为45 km/h,行人与车辆碰撞位置时分别处于车辆前保险杠前端1/2和1/3处。分析结果表明,该耦合模型可以较准确地再现事故中的行人动力学响应;行人碰撞保险杠前端中间(即1/2处)位置时的头部损伤较1/3处更严重;头部损伤在本文所分析的变化范围内随挡风玻璃角度的增加呈先减小后增加的变化趋势,且当挡风玻璃角度位于32°~34°左右时损伤风险较低。     

基于行人友好的车身结构研究

在行人保护的研究中,头部与汽车发动机罩撞击损伤研究是重要的内容.汽车发动机罩结构形式是影响行人头部伤害程度的一个重要因素,已有的研究成果是通过改进发动机罩板的结构达到降低头部撞击加速度.本文通过改变发动机罩的边界条件达到了降低头部撞击损伤的目的,通过分析验证了这个结论.     

改进的车身结构减振缓冲性能的研究

在行人保护的研究中,头部与汽车发动机罩撞击损伤研究是重要的内容之一.汽车发动机罩的结构形式是影响行人头部伤害程度的一个重要因素.已有的研究成果是通过改进发动机罩板的结构达到降低头部撞击加速度值.本文利用数学模型分析了在改变现有发动机罩边界条件的情况下,头部模型撞击的加速度值,并和已有的试验结果进行了对比,表明该结构能够达到降低头部撞击加速度的目的.     

面向人体损伤的人车碰撞事故再现

应用多刚体的车辆与假人模型,将人体伤害作为事故场景布置以及再现结果评估的重要依据,使用分析法与模拟法相结合的优化方法研究人车碰撞事故再现.针对人车碰撞中行人易受伤害的特点,提出了一个面向人体损伤的行人事故再现评估模型.将此评估模型作为优化方法中的目标函数,将碰撞场景、碰撞前车速作为设计变量,事故资料作为约束条件,经多刚体动力学算法求解,手工实现了事故再现的最优结果.将该方法及评估模型应用到一起真实交通事故中,仿真结果与法医鉴定结果大致吻合,初步验证了此方法与模型的可行性.     

车辆与行人碰撞事故中下肢损伤风险研究

研究行人与车辆碰撞事故中下肢损伤风险,并确定碰撞速度和行人年龄、身高以及体重等损伤相关参数值在下肢轻微损伤组和严重损伤组之间的分布是否存在显著差异。为此,首先从德国深入事故研究数据库(GIDAS)中挑选出354个带有行人下肢损伤的案例来进行单因素方差分析,接着利用逻辑回归分析方法建立行人下肢严重损伤风险函数模型,分析车辆碰撞速度和行人年龄、身高以及体重对行人下肢严重损伤风险的影响。分析结果表明:碰撞速度和行人年龄是影响行人下肢严重损伤的显著性因素,而体重与身高不是影响行人下肢严重损伤的显著性因素;并且行人下肢严重损伤风险与碰撞速度以及行人年龄正相关。当碰撞速度为43 km/h时,行人下肢严重损伤风险达到50%。     

基于行人腿部保护的保险杠吸能结构设计

建立了小腿与轿车前部的碰撞有限元模型,并运用LS-DYNA仿真求解,通过与Euro-NCAP实验结果对比,验证了有限元模型的准确性。对比分析5种截面形式的吸能板对行人的保护效果,选择了一种对行人保护效果较好的截面。为优化行人保护效果,以吸能板厚度和材料屈服强度为设计变量构造全因子实验,并拟合出腿部三项伤害指标的响应面模型。采用序列二次规划优化方法,得到对行人腿部保护较好的参数组合,为钢制吸能板的设计提供了依据。     

考虑圆柱铰链间隙的多刚体系统动力学计算方法

为了研究含圆柱铰链间隙的多刚体系统动力学计算方法,针对三维圆柱铰链的结构特点,给出了一种改进的接触对确定方法,构造了空间间隙圆柱铰链接触分离切换点的判别方法。法向接触力采用Lankarani与Nikravesh的连续接触力模型计算,切向摩擦力采用修正的Coulomb模型计算,综合考虑接触分离状态建立了统一形式的动力学方程。最后对比间隙铰链机构和理想铰链机构运动,结果表明圆柱铰链间隙在短时间内对其他构件的运动影响很小,但严重增大了铰链内部的碰撞力,长时间运动后机构的位移、速度、加速度与理想铰链偏差变大,但接触摩擦力使圆柱铰链的轴向运动受到抑制。间隙圆柱铰链的研究方法和结果为相关和更复杂的含间隙圆柱铰链机构的运动分析提供了理论参考。     

六自由度微动工作台柔性铰链设计

主要介绍了用于六自由度微动工作台的柔性铰链即双向柔性铰链和万向柔性铰链的设计过程，根据微动台中柔性铰链的设计要求，分析了微动台运动时驱动力与铰链变形的关系，确定了满足驱动力条件的柔性铰链刚度范围，并结合柔性铰链强度条件、工作台动态特性以及柔性铰链转角刚度与结构尺寸的关系，进一步确定柔性铰链的刚度和结构尺寸，合理设计柔性铰链．另外，通过有限元分析软件分析了柔性铰链最大受力时的应力分布情况．对柔性铰链的强度进行了校核，进一步保证了柔性铰链设计的正确性．     

安全气囊系统及关键技术

汽车发生碰撞事故时,在惯性的作用下,司机和乘客会高速撞向方向盘等车内部件,受到伤害.在汽车上安装安全带和安全气囊等保护系统,可以在撞车时把乘客约束在座椅上,限制乘客头部、胸部的移动距离,避免与车内部件发生剧烈碰撞,从而起到保护作用.本文对安全气囊组成及关键技术加以分析,对提高行车安全和保护乘员生命安全有着积极的意义.     

间隙铰链对平面机构碰撞动力学特性影响分析EI北大核心CSCD

为了研究间隙铰链对机构动态性能的影响,建立了一种含轴向尺寸的线接触碰撞铰模型,在此基础上提出一种改进的非线性法向碰撞力模型和修正的切向库伦摩擦力模型,以平面含间隙铰链曲柄滑块机构为研究对象,通过不同间隙值下的滑块加速度、间隙铰链处接触力、加速度频谱以及速度-加速度相图分析,研究了间隙值对机构碰撞动力学特性的影响规律。研究结果表明:间隙会导致机构动态性能出现明显的振荡现象,且随着间隙值的增大,振荡加剧、振荡幅值上升,但振荡频率降低;同时,在间隙铰链的影响下,机构动态特性呈现出非线性现象,且间隙越大,非线性现象越明显。     

Optimization of a reversible hood for protecting a pedestrian's head during car collisions

This study evaluated and optimized the performance of a reversible hood (RH) for the prevention of the head injuries of an adult pedestrian from car collisions. The FE model of a production car front was introduced and validated. The baseline RH was developed from the original hood in the validated car front model. In order to evaluate the protective performance of the baseline RH, the FE models of an adult headform and a 50th percentile human head were used in parallel to impact the baseline RH. Based on the evaluation, the response surface method was applied to optimize the RH in terms of the material stiffness, lifting speed, and lifted height. Finally, the headform model and the human head model were again used to evaluate the protective performance of the optimized RH. It was found that the lifted baseline RH can obviously reduce the impact responses of the headform model and the human head model by comparing with the retracted and lifting baseline RH. When the optimized RH was lifted, the HIC values of the headform model and the human head model were further reduced to much lower than 1000. The risk of pedestrian head injuries can be prevented as required by EEVC WG17.     

Child pedestrian anthropometry: evaluation of potential impact points during a crash

This paper highlights the potential impact points of a child pedestrian during a crash with the front end of a vehicle. Child anthropometry was defined for ages between 3 and 15 years. It was based on the measurement of seven different segment body heights (knee, femur, pelvis, shoulder, neck, chin, vertex) performed on about 2,000 French children. For each dimension, the 5^th, 50^th and 95^th percentile values were reported, and the corresponding linear regression lines were given. Then these heights were confronted with three different vehicle shapes, corresponding to a passenger car, a sport utility vehicle and a light truck, to identify impact points. In particular, we show that the thigh is directly hit by the bumper for children above 12 years of age, whereas the head principally impacts the hood. The influence of child anthropometry on the pedestrian trajectory and the comparison with test procedures in regulation are discussed.     

Technical Analysis and Improvement of the Pedestrian Safety Protection of a Car Hood

The pedestrian protection technology must be used in automotive design if China-made automotives want to compete and grow strong in the world in the future. In this paper, a CAE simulation analysis is made for a domestic sedan car hood to check whether it meet the pedestrian safety protection laws and regulations. Results show that the original car cannot meet the demands of the rules. In order to meet the standards of the pedustrian protection rules, the car hood should undergo structural improvements. Tested again by CAE simulation analysis, the car after a series of improved design can reached the 3-star class EuroNCAP(Euro New Car Assessment Program)standard of the car pedestrian safety protection laws and regulations.     

Field relevance of a suite of rollover tests to real-world crashes and injuries

The objective of this study was to assess the distribution of rollover accidents occurring in the field and to compare the vehicle kinematics in the predominant field crash modes with available laboratory tests. For this purpose, US accident data were analyzed to identify types and circumstances for vehicle rollovers. Rollovers were most commonly induced when the lateral motion of the vehicle was suddenly slowed or stopped. This type of rollover mechanism is referred to as "trip-over". Trip-overs accounted for 57% of passenger car and 51% of light truck vehicle (LTV) rollovers. More than 90% of trip-overs were initiated by ground contact. Fall-overs were the second most common rollover type, accounting for 13% of passenger car and 15% of LTV rollovers. Bounce-overs only accounted for 8% of both passenger car and LTV rollovers.The FMVSS 208 dolly and the ADAC corkscrew rollover tests are well-known laboratory tests, but do not simulate many of the real-world rollovers. Three additional tests have been devised to more fully address the field relevant conditions identified in this study. To do so, assumptions were made and adding the new laboratory tests (soil-trip, curb-trip and ditch fall-over) increases representativeness to 83% of passenger car and 75% of LTV rollovers reported in the field. Accident data were also used to identify injuries in belted drivers so the information could later be used to better understand occupant kinematics in various roll conditions. The injury distribution for belted/non-ejected drivers was assessed for trip-over, fall-over and bounce-over accidents. Serious injuries (AIS 3+) were most common to the head and thorax, in particular for bounce-overs. Head injuries occurred from contact with the roof, pillar and the interior, while thoracic injuries resulted from contact with the interior and steering wheel assembly. Field data are useful in the development of laboratory test conditions for rollovers as it provides insights on the significance of various rollover types, understanding of injury biomechanics, guidance for future testing and inputs for mathematical modeling.     

基于启发式算法的乘用车物流运输问题分析

伴随着汽车工业的高速崛起,乘用车物流运输问题也快速走进人们的视野。由于现在很多物流公司在制定运输计划时主要依赖调度人员的经验,在面对复杂的运输任务时,往往效率较低且运输成本不尽理想。考虑到影响乘用车物流运输成本的主要因素分别为轿运车的使用数量、轿运车的单价以及行驶里程数等等,本文采用建立逐级目标的模式,应用启发式算法,结合计算机软件,给出了求解乘用车物流运输问题的数学模型。应用此模型求解了2种不同类型的乘用车物流运输问题,提出了合理的运输方案。此项工作对今后物流公司处理此类运输问题提供了重要的参考价值。     

试析空调客车热泵取暖的优势及实施的技术途径

根据铁路客车供热现状,通过理论计算分析了采用热泵取暖的可行性,并指出了其优势所在;提出了铁路空调客车冬季采用热泵取暖需要克服的主要技术问题及实施途径。     

The fatality and injury risk of light truck impacts with pedestrians in the United States

In the United States, passenger vehicles are shifting from a fleet populated primarily by cars to a fleet dominated by light trucks and vans (LTVs). Because light trucks are heavier, stiffer, and geometrically more blunt than passenger cars, they pose a dramatically different type of threat to pedestrians. This paper investigates the effect of striking vehicle type on pedestrian fatalities and injuries. The analysis incorporates three major sources of data, the Fatality Analysis Reporting System (FARS), the General Estimates System (GES), and the Pedestrian Crash Data Study (PCDS). The paper presents and compares pedestrian impact risk factors for sport utility vehicles, pickup trucks, vans, and cars as developed from analyses of US accident statistics. Pedestrians are found to have a two to three times greater likelihood of dying when struck by an LTV than when struck by a car. Examination of pedestrian injury distributions reveals that, given an impact speed, the probability of serious head and thoracic injury is substantially greater when the striking vehicle is an LTV rather than a car.     

旅客列车硬座车厢内气流模拟与浓度场分析

采用稳态不可压缩雷诺时均N-S方程、k-ε湍流模型,对旅客列车空调硬座车厢内气流场和浓度场进行了数值计算。采用立方体代表旅客,以人体呼出的CO2作为代表性污染物,研究了非空载下车厢内气流和浓度分布。计算结果表明：现有的送风方式除车厢两端外,车厢内沿长度方向气流分布比较均匀;人体散热和太阳辐射对车厢内流场温度场影响较大,非空载时车厢内流场分布与空载时有较大差别,太阳照射和人体产生的热气流使车厢内存在较大的温度梯度;车厢内过道区浓度较低,但座位区由于人员集中,人体呼吸区污染物积聚,浓度偏高,且车厢中部断面污染     

年轻消费者对轿车前视造型相似性的认知研究

目的 探索年轻消费者群体对轿车前视造型相似性的认知特性。方法 依据排量和品牌筛选出的轿车前视造型,进行相似性判断消费者调研,进行聚类分析和多维尺度分析。进一步对获得的分类结果和消费者知觉图进行定性分析。结论 在消费者认知空间中,76款轿车前视造型的分布与设计特征变化存在着明确的规律。这些规律反映在知觉图的横向与纵向维度上以及各个象限中,体现为整体造型风格和局部设计特征两个层面,此外,多数分类中轿车前视造型具有各自的共同设计特征。     

Energy‐Absorbing Behavior of Aluminum Foams: Head Impact Tests on the A‐Pillar of a Car

Hundreds of compression tests have been performed in recent years to investigate the energy‐absorbing behavior of metal foams, which is mainly characterized by the “deformation plateau”. Plateau value and plateau length describe the basic behavior quite well and allow comparison of various foams, but in practice the geometry of the absorbing component and the assembly in the system with supports and panels also influence the behavior. The aim of this work was to evaluate the energy‐absorbing behavior of an aluminum foam absorbing element in an A‐pillar system of a real car. In cooperation with the Austrian car manufacturer Steyr–Daimler–Puch Fahrzeugtechnik, a Magna Steyr company, the deformation element in an A‐pillar of a passenger car was developed and tested. The geometry was given by the design of the steel frame and the cover panel of the pillar. The deformation elements were foamed at ARC Leichtmetallkompetenzzentrum Ranshofen GmbH (LKR) by the powder metallurgical process route. The head impact against the A‐pillar in overturning was simulated by the standard test procedure FMVSS 201u and the head injury criterion (HIC) was measured. The head impact tests were performed by impact of a free motion head (FMH) dummy against the A‐pillar in a complete car mounted in a special test rig. In a couple of test runs, the required HIC of less than 1000 could be achieved. The measured HIC values depend on the density and the structure of the aluminum foam, as well as on the deformation element geometry. These parameters were investigated and simulations concerning component behavior were carried out.