面向受害人体型特征的交通事故再现计算方法

面向受害人体型特征的交通事故再现依据事故遗留下的制动印迹、车身变形、人体损伤等信息,建立汽车及符合受害人体型特征的人体模型,利用数值仿真技术获得碰撞前车辆速度及车人接触位置,结合多刚体动力学和人体损伤分析等理论,得出车辆变形及人体损伤部位的生物力学数值.通过上述方法对一起车人碰撞事故案例进行实际应用,并比较行人不同体型特征对事故仿真结果的影响,分析结果表明:与采用标准百分位假人仿真结果相比,计算结果能够更好的与现场勘测及法医鉴定相吻合,从而为交通事故责任认证提供科学的理论依据和数值参考.     

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.     

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Facet模型及组合式假人对汽车-摩托车碰撞事故的仿真

为了更好的解决汽车-摩托车碰撞事故的仿真再现问题,一种新的仿真模型及方法被提出。该方法采用Facet模型建立事故汽车及摩托车的三维模型,采用组合式假人模型建立骑车人的三维模型。由Photomodeler软件得出碰撞初始条件,并利用Madymo软件对事故碰撞过程进行直观的三维仿真再现。针对一起实际的轿车与摩托车碰撞事故,采用上述仿真模型及方法进行事故模拟。仿真结果与实际事故情况可以较好吻合,人体损伤数据与法医鉴定结果可以较好吻合,从而验证了此种仿真模型及方法的可行性及有效性。     

基于Pc-Crash的车-人事故再现*

提出基于Pc-Crash的车-人事故再现方法,即以Pc-Crash为仿真平台,构建事故现场及车、人多刚体模型,以车、人接触部位及人、车最终停止位置等事故信息为重要证据对事故进行仿真,并利用人体损伤等其他事故信息验证仿真结果的合理性,最后利用不确定性分析理论评估所得结果的不确定度。以一车-人碰撞事故为例,演示了该方法的步骤。案例再现分析中,事故信息都得到合理利用,并借助响应曲面法与蒙特卡罗方法获得了事故再现结果的分布。算例表明,利用该方法所得再现结果不仅更为客观,且能为事故鉴定提供更多有效信息。     

汽车-自行车碰撞事故三维仿真再现研究

针对一起实际的汽车与自行车碰撞事故，运用多刚体动力学方法建立事故小客车与自行车及骑车人碰撞的三维多刚体动力学仿真模型，利用MADYMO对事故碰撞过程进行了直观的三维仿真再现，分析研究它们在碰撞后的动力学行为特性，计算得出碰撞时刻小客车车速为正确鉴定事故提供了科学的参考依据。仿真再现结果与实际事故情况能较好吻合，初步验证了仿真方法和模型的可行性。     

运输车辆碰撞事故对在建隧道影响的数值模拟

利用显式非线性有限元法对在建狭长隧道施工中运输车辆碰撞事故进行数值模拟,并研究事故对周围隧道产生的影响。为准确的模拟运输车辆碰撞时对周围隧道的影响,基于拟实建模方法,建立了大型输水工程青草沙隧道及运输车辆的三维有限元模型。通过三维动态接触方法来模拟轮轨之间的动力相互作用,能够模拟打滑、脱轨等实际接触情况。采用了基于罚函数的接触算法和基于段分类的搜索方式,对该大型输水工程隧道在运输车辆发生碰撞时的动态响应进行仿真计算。分析了运输车辆发生碰撞后车与管片的运动规律,以及在建隧道的动态响应,这对事故的防范及处理有指导作用。利用上海超级计算机曙光5000A进行并行计算,分析了对于大型工程问题的模拟仿真采用并行计算的加速效果。     

桥梁结构地震碰撞分析模型的碰撞刚度计算方法研究

针对桥梁结构地震碰撞模拟问题,文中分别推导了基于波动理论的直杆共轴碰撞模型和基于接触单元法的刚体碰撞模型中相应的最大碰撞变形的计算式,并基于二者相等的关系给出了Kelvin模型和Hertz-damp模型中相应碰撞刚度的计算方法,并对所建议方法的合理性和精确度进行了验证分析。研究结果表明,文中建立方法计算的Kelvin模型的碰撞刚度数值明显小于较短主梁的轴向刚度,这一点与以前学者基于实测数据分析得到的结论相一致。数值分析结果表明,相比以前的碰撞刚度计算方法,采用本文建议的方法确定Hertz-damp模型的碰撞刚度时,可以显著提升其碰撞模拟精确度。     

叶片冠间接触碰撞数值模拟及实验研究

研究了自带冠叶片冠间接触碰撞的动力学特性及减振机理。利用弹性力学理论对叶片冠间接触碰撞问题建立碰撞弹性力模型,叶片的冠间接触碰撞进行了数值模拟,并通过实验验证了理论分析的结果,进而得到了叶片接触碰撞系统的非线性响应特性及减振机理。     

四刚体人体行走模型及其人行荷载分析EI北大核心CSCD

为模拟人体行走过程中的力学行为,运用多刚体模型对人体进行简化建模,建立了四刚体‑四自由度的人体动力学模型。运用欧拉‑拉格朗日方程的方法推导了动力系统摆动阶段动力学方程。为了使四刚体模型的行走具有拟人性,使用贝塞尔曲线对驱动自由度的运动轨迹进行了规划,从而将多自由度的运动方程简化为求解单自由度常微分方程的边界值问题。将数值模拟结果与试验和荷载模型进行对比,验证了所建立模型的可行性。     

Biomechanical assessment of soft tissue cervical spine disorders and expert opinion in low speed collisions

The multidisciplinary research of injury mechanisms and injury prevention requires the assessment of the technical and biomechanical circumstances of a collision; moreover, the causality assessment in the individual cases is facilitated by taking these aspects into account. In fact, only specially trained engineers and biomechanical experts are in a position to evaluate these relevant basic facts. In many crucial court cases, important technical factors such as collision angle, structural stiffness, extent of intrusion and the vehicle's velocity change are often ignored. The purely medical causality assessment is often based only on a coincidence of time of the 'accident' and the onset of the disorders. Unfortunately, statements about the 'accident speed' or the nebulous 'accident energy' are often made by clinicians with neither a proper collision documentation nor the necessary biomechanical and technical background. In order to overcome shortcomings of injury causality assessment as well as the terminology associated with soft tissue cervical spine injuries, a subdivision of the term 'accident severity' into four classes is proposed. Consequently, an 'accident severity assessment' can only be performed by a collaboration of four corresponding classes of experts, i.e. the engineer (dynamic loading of the vehicle), the biomechanical expert (biomechanical loading of the occupant), the physician (clinically diagnosable injuries), and eventually the psychiatrist (subjective sequelae individually experienced by the victim).     

冗余约束多刚体系统摩擦碰撞问题的数值求解方法

针对冗余约束多刚体系统的摩擦碰撞问题,以牛顿恢复系数作为碰撞终止条件,以离散化的系统动力学方程和线性规划理论为基础,建立了相应的混合互补模型。为有效求解该模型,利用最小二乘法和线性化方法,将混合互补模型转化为标准的线性互补模型,用线性互补模型的求解算法进行数值求解。接着,提出一种直接投影修正算法对碰撞计算过程进行修正,有效防止了碰撞加剧约束违约的现象。最后,通过一个算例,验证了数值求解方法和修正算法的有效性。     

Epidemiological data and ranking home and leisure accidents for priority-setting

OBJECTIVE: To determine how to use the multitude of available epidemiological data to rank accidents for prioritisation of prevention. METHODS: A stepwise method to rank accidents for priority-setting at any time is proposed. The first step is to determine the overall objectives of injury prevention. Based on these objectives, the relevant epidemiological criteria are determined. These criteria need to be weighed by experts in such a way that these weights can be used for every new cycle of priority-setting. Thus, every time the method is applied: first, the relevant types of accidents are identified; second, the epidemiological criteria are determined per type of accident; and third, the types of accidents are ranked by means of standardised weights per criterion. The proposed indirect method is illustrated by an empirical example. The results were compared with a direct method, i.e. ranking by an expert panel. RESULTS: In the pilot, we ranked four age groups of victims of a home and leisure accident: 0-4, 4-19 and 20-54 years of age, and victims aged 55 years or older. The resulting rankings differ largely per application; number one are victims older than 55 years or those of 20-54 years. CONCLUSIONS: The proposed method enables a structured, transparent way to set priorities for home and leisure accidents. It is a promising method, although further development is clearly necessary, based on the actual application of the model.     

事故仿真再现结果不确定性分析方法

越来越多的交通事故依赖于仿真软件进行再现分析,事故仿真再现结果的不确定性问题亦越来越受到重视。介绍了可用于研究该问题的上下界法、差分法以及响应曲面法;接着通过分析给出了各方法所需仿真次数;然后借助三个算例验证了各方法的实用性与适用范围,并总结出各方法的优缺点,发现响应曲面法适应性最强;最后探讨了求解事故再现中大不确定性问题的响应曲面法。所得结论可用于指导研究事故仿真再现结果的不确定性问题。     

Analysis of the effect of car size on accident injury probability using automobile insurance data

The Highway Loss Data Institute (HLDI) compiles injury and collision claim information from major insurance companies. These data have indicated that a disproportionately large number of injury claims are made for small cars. As a result, it might be concluded that small cars increase injury risk to their occupants. Recent advertisements by a major automobile manufacturer suggest a similar conclusion should be drawn from these data. In this paper it is shown that the apparent higher injury risk attributed to small cars can reflect the behavior of persons driving small cars. The number of injury claim accidents per collision claim accident is examined as an alternative measure of injury risk. Possible problems in interpretation are discussed.     

基于不确定语言信息的物流供应商选择

为解决传统供应商的选择与评价过程中专家评判的模糊性和不确定性问题,提出了一种基于不确定语言信息的物流服务供应商选择方法。该方法以不确定语言变量来表征专家的评判从而避免了决策信息的丢失。继而建立了物流服务质量评价属性的权重优化模型,并构造拉格朗日函数来求解该模型,得到评价属性的最优权重。接着利用不确定语言加权几何平均（ULWG）算子集结专家评判信息,则得到供应商的优先排序。给出了基于不确定语言信息的供应商选择的算法步骤和应用实例。     

Expert judgments in the cost-effectiveness analysis of resource allocations: a case study in military planning

We consider resource allocation problems in which agents are assigned to tasks with the aim of (1) minimizing the costs of assigning the agents and (2) maximizing the overall value resulting from the completion of tasks. Often, such assignment problems are challenging, because it may not be known to what extent the agents can complete tasks or what the value of either full or partial task completion is. Furthermore, it may be difficult to determine how important the tasks are relative to each other. In this paper, we therefore develop an optimization framework that helps determine for a range of levels of resource expenditure (1) which combinations of agents are cost-effective and (2) to which tasks these agents should be assigned. The parameters for the optimization problem can be derived, for instance, by eliciting evaluation judgments from experts. We also provide tools for analyzing which combinations of agents outperform others in view of the judgments of all experts, and which ones are cost-ineffective based on the judgments of some or all experts. A computational algorithm is presented, and the framework is illustrated by reporting a real application in military planning.     

Statistical adjustment for misclassification of seat belt and alcohol use in the analysis of motor vehicle accident data

The use of seat belts and alcohol is often mis-reported in police motor vehicle accident reports for a number of reasons. To avoid penalties, occupants often over report seat belt use and under report alcohol use. Police officers sometimes fail to account for evidence such as presence of belt burn, condition of belts, odor of alcohol, crash patterns, etc. Biased conclusions result when using misclassified accident data to estimate the effectiveness of seat belts in preventing injuries and reducing medical costs. We investigated the effects of misclassification of seat belt and alcohol use on the odds ratio of injury as well as medical costs. A statistical method and a SAS program were developed to adjust odds ratios of injury and medical cost estimates to account for misclassification of seat belts and alcohol use. The method allowed for incorporation of variables that could affect misclassification of seat belt and alcohol use. We conducted a Monte Carlo simulation and found that when there were large differences between the misclassification rates for major and minor injury, the unadjusted odds ratio could have up to a 90% bias while our adjusted odds ratio was effectively unbiased. To illustrate the method, we estimated the misclassification rates of seat belt and alcohol use by comparing merged police and hospital reports from Nebraska motor vehicle accident data sets (1996-1997) and then evaluated the bias of the odds ratio of injury and medical costs estimates due to misclassification. Our results showed that the bias of the odds ratio of injury and medical costs due to misclassification of seat belts and alcohol use depended both on the amount of misclassification and the reported frequencies. Misclassification about seat belt and alcohol use only slightly biased the unadjusted odds ratio estimates and mean hospital charge, while misclassification resulted in approximately a 69% underestimate of the total medical costs savings due to seatbelts. However, due to the small size of the merged Nebraska police and hospital data set used to estimate misclassification rates, these results are likely somewhat imprecise.