汽车模拟碰撞吸能器的仿真分析

介绍一种新型汽车模拟碰撞用液气缓冲吸能器。应用小孔节流理论,建立液气缓冲器的力学模型,同时对各主要参数对缓冲器吸能特性的影响进行讨论。结果表明:经过参数优化后,该液气缓冲器能够复现不同碰撞车速下的加速度波形要求,可广泛用于汽车安全部件的设计开发和试验验证。     

可伸缩式汽车碰撞缓冲吸能装置的试验与仿真研究

介绍了可伸缩式汽车碰撞缓冲吸能装置的工作原理。针对某量产车型的前部结构设计制造了该碰撞缓冲吸能装置的样件,完成了样车的结构和控制系统的改装。建立了吸能装置的有限元模型,研究了其在正面碰撞时的响应特性。同时,采用台车碰撞试验的方法,研究了该装置在伸出及缩回状态下的高低速碰撞性能。仿真和试验研究结果表明,该碰撞缓冲吸能装置在伸出状态下能有效增加车辆的碰撞缓冲吸能空间,从而改善碰撞吸能过程,更好地保护车内乘员。在缩回状态下,该装置不会对原车型造成不利影响。     

蜂窝铝缓冲结构的仿真分析及应用研究

为得到具有良好耐撞性能的缓冲结构,提升车辆在碰撞中的安全性,以蜂窝铝为研究对象,建立了有限元模型,研究了不同壁厚参数的正六边形铝蜂窝结构的吸能特性,并进一步分析了截面尺寸对缓冲结构碰撞特性的影响,最终结合实际应用,给出了性能合格的缓冲结构方案。通过等效的台车测试,试验和仿真结果的基本一致,验证了有限元模型的正确性。研究结果表明,蜂窝铝缓冲结构能有效吸收车辆的碰撞动能,并降低碰撞过程中车辆的最大减速度,研究对车辆缓冲结构及其参数的选定有重要的参考意义。     

基于SimulationX的挖掘机高压斗杆缸缓冲装置的仿真与试验研究

为研究高压油缸的行程末端缓冲装置的缓冲性能,获得油缸缓冲行程阶段的压力、流量等参数,以一款国产挖掘机高压斗杆缸作为研究对象,将计算机仿真技术应用到实际工程研究中。基于SimulationX仿真软件搭建了挖掘机工作装置液压系统的仿真模型(特别是缓冲模型),开展了液压-机械多体动力学联合仿真;在典型工况下对液压挖掘机斗杆缸的压力、流量等参数进行了试验,通过比对仿真结果,对控掘机液压系统仿真的准确性进行了评价。结果表明,所建立的仿真模型是合理的、科学的,该仿真技术在工程领域更进一步的推广是可行的。     

车门内饰板总成耐撞性实验分析及优化

应用试验方法和有限元法对车门内饰板总成的侧面耐撞性进行研究,并在此基础上优化缓冲块的结构设计,以获得更高的吸能特性。参照国家标准和行业规范,确定门内饰板总成胸部、腹部及胯部的碰撞区域,设计、制造冲击头,并在摆锤试验台上对其进行耐撞性测试;基于LS-DYNA平台,建立门内饰板总成的有限元模型,其中材料模型中主要参数均通过实验直接获取,基于建立的有限元模型进行耐撞性分析,模拟结果和试验结果符合较好;以建立的有限元模型为基础,基于实验设计和支持向量机方法建立缓冲块吸能特性的替代模型,并以此为基础对缓冲块进行结构优化。优化后缓冲块吸能增加86.0%,门内饰板总成吸能增加42.2%。     

数控机床加工仿真技术研究

随着生产自动化、智能化以及数字化等水平的不断提升,数控机床在工业生产领域的应用越来越多。数控机床技术也在不断更新换代中,其中机床加工中的仿真技术应用就是一个突出的方面。通过对机床综合加工过程进行模拟仿真,可以避免在加工生产中出现一些干扰、矛盾和碰撞等问题,从而不断提升数控机床的加工精度和机床加工效率。因此,以数控机床加工仿真技术为例,分析仿真技术的内涵和应用特点,介绍在数控机床中仿真技术的加工优势,并研究仿真技术在数控机床加工中的具体应用。     

铝制车身仿真方法研究及试验对标分析

基于某MPV车型进行铝制车身碰撞安全仿真方法的研究,应用内聚力材料模型模拟胶粘连接和应用Constrained_SPR2模型模拟自穿刺铆钉,并与正面碰撞试验结果进行对标,从车身关键零部件变形模式、B柱下部加速度曲线和其他试验数据等方面进行了对比分析。结果表明:正面碰撞仿真结果与试验高度吻合,内聚力材料模型和Constrained_SPR2模型能分别有效模拟胶粘和铆接连接区域实际碰撞情况。     

双组元缓冲装置的设计与应用研究

讨论了一种可用于防汛水闸闸门启闭碰撞过程中的双组元缓冲装置,其原理是将弹簧置于一个可移动活塞上,通过改变液流腔流量控制活塞的移动速度,以此降低碰撞力。文章对双组元缓冲原理进行了详细的理论分析,并进行了实验研究,从而证明双组元缓冲的优越性。应用相似理论,建立了双组元缓冲装置的模型和实型间相似关系,设计水闸闸门实型结构的重要结构参数,大大简化了工程上该类复杂碰撞缓冲问题中的结构设计。     

面向空间软捕获的双模传动关节设计与仿真

星载抓捕机构在空间目标捕获任务中发挥着重要作用,然而空间捕获时的对接碰撞很容易导致抓捕机构失稳。针对空间捕获软对接问题,设计了一种双模传动软接触关节,既能实现双自由度刚性传动,同时可通过阻尼吸振实现空间六维碰撞的缓冲和卸载。在ADAMS仿真软件中建立单关节星载抓捕机构模型,通过空间单维和六维碰撞下的仿真研究,验证了软接触关节缓冲和卸载空间六维碰撞的原理及其对基座与关节稳定的有效性。进一步建立三关节星载抓捕机构模型,通过空间六维碰撞下的仿真试验,说明了双模传动软接触关节在多关节抓捕机构中应用的有效性。     

基于CFD动网格仿真技术的液压缸缓冲特性研究

以挖掘机液压缸为研究对象,对液压缸前腔缓冲装置的缓冲动态特性进行研究。主要是基于CFD动网格仿真技术,建立了缓冲结构的Matlab仿真模型和CFD仿真模型,根据已有的液压缸缓冲结构尺寸获得仿真输入条件,仿真得到了液压缸缓冲过程的缓冲压力动态特性。经过与实物测试数据比对,验证了计算方法和数学模型的正确性。     

Key issues and developments in modelling and simulation-based methodologies for manufacturing systems analysis, design and performance evaluation

Discrete event simulation (DES) has been widely applied to modelling and simulation of computer and engineering systems and is an active field of research that has now evolved from 2D to 3D discrete event simulation. This paper attempts to address several key issues in a successful implementation of DES models based on our own and the previous experiences of others. It describes the common basis, which forms the core for the application of modelling and simulation methodologies that are available to support manufacturing systems analysis, design and performance evaluation. Through a comprehensive literature survey, this paper summarises and compares the most widely used optimisation techniques for simulation of manufacturing systems; an overview of the recent and popular simulation languages and packages available for the modelling and simulation community and the classification of their utility for modelling and simulation of manufacturing systems is also given. Finally, this paper summarises and reports the latest development in the most exciting world wide web (www)-based simulation techniques that represent a future that may completely change the nature and future exploitation of modelling and simulation technology in industry.     

A study to maximize the crash energy absorption efficiency within the limits of crash space

The design of an engine room is important to protect the passenger from a crash impact by improving the absorption of the crash impact energy. The side member in the engine room absorbs most of the crash impact energy when the vehicle experiences a frontal crash. The side member is of two types: hat and ‘U.’ Analysis of the extent of energy absorption and the mechanism of the side member are necessary through a collapse mode in various load conditions. In this study, the design of experiments was used for evaluating the characteristics of the absorption of crash energy by side members through design variables. First, crash analysis was performed by experiment number extracted from the design of the experiment. Then, using the results of crash analysis, multiple regressions were conducted and sensitivity analysis performed for each design variable. Finally, the optimum design was developed for maximizing the absorption energy per unit weight considering various boundary conditions. In the present study, as a basic step for modeling the fatigue behavior of an extruded Al alloy cylinder, the fatigue crack growth data of the alloy was collected in two orientations. Microstructural analysis revealed that the material had recrystallized grains and clusters of constituent particles aligned in the direction of extrusion. Fatigue life of the samples revealed a shorter fatigue life representing a higher fatigue crack growth rate in the transverse direction.     

基于逐步回归模型的汽车碰撞安全性多目标优化

汽车结构的耐撞性及碰撞吸能优化是现代汽车工业的重要研究内容。面对传统优化方法难以找到汽车结构耐撞性问题多目标参数最优解的难题,在汽车结构碰撞安全性问题的研究中,结合试验设计、响应表面模型和有限元仿真程序提出一种基于逐步回归模型的多目标优化设计方法。利用该方法对以汽车前端结构的加强件作为设计变量,以整车质量、脚踏板在碰撞过程中的侵入量和整车碰撞加速度积分值作为目标函数的汽车100%正面碰撞以及40%正面偏置碰撞的多目标优化问题进行仿真优化研究,结果表明该方法对于汽车结构碰撞安全性的优化具有明显的效果。     

Crashworthiness assessment of front side members in an auto-body considering the fabrication histories

This paper is concerned with crash analysis of a front side member in an auto-body considering the effect of fabrication. The front side member is fabricated with sheet metal forming processes that induce forming histories such as plastic work hardening and non-uniform thickness distribution. Numerical simulation is carried out with LS-DYNA3D in order to identify the forming effect on the crashworthiness. The result shows that the crash analysis of the front side member with considering the forming history leads to a different result from that without considering the forming effect. The analysis calculated crash mode, the reaction force and the energy absorption for crashworthiness assessment with the forming effect. The analysis results demonstrate that the design of auto-body members should be carried out considering the forming history for accurate assessment of crashworthiness.     

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 pans to the impact of auto body are not considered.The goal of this research is to study the application of hot forming high strength steeI(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.     

Experiment and computer simulation of particulate suspensions under shear flow

In this paper is described the role of molecular simulation as a useful quasi-‘experimental’ tool to help in understanding the interplay between molecular structure under shear flow and the manifested tribology/rheology. The development of non-equilibrium molecular simulation techniques are discussed, from the molecular dynamics approach through to the modelling of dispersions by brownian dynamics. Recent advances and extensions of the technique to weakly flocculated systems, such as electro-rheological fluids, are described.     

基于鲁棒性的概率优化设计在薄壁构件耐撞性中的应用

汽车结构的耐撞性及碰撞吸能优化是现代汽车工业重要的研究内容。耐撞性的优化涉及材料与结构的众多参数，传统的确定性优化设计、碰撞仿真及实验往往只能在一定程度上改善结构的碰撞性能，而无法评估设计参数的可靠性和目标函数的鲁棒性，以及在给定可靠性约束条件下使目标函数的鲁棒性达到最优状态。将实验设计、响应面模型和蒙特卡罗模拟技术相结合，构造了基于产品质量工程的6σ鲁棒性优化设计方法，实现了对设计目标的优化，并提高了设计变量的可靠性和目标函数的鲁棒性。     

Explicit optimization method for cutting-screw-thread on the basis of dual-RSM

To obtain the explicit function for optimizing the cutting-screw-thread (CST) in crash, the simulations of frontal crash at the speed of 56 km/h have been carried out in VPG. The peak acceleration in crash has been taken as the evaluation index of energy absorption characteristics. First, the single factor experiment was taken based on six parameters affecting on the absorption characteristics of CST. Second, the peak acceleration function of each parameter by using response surface method (RSM) is obtained. Third, the explicit resultant peak acceleration function of six parameters by using RSM again is obtained. A dual RSM-based explicit method is proposed. According to this function, the best size dimensions of CST in different crash conditions could be easily obtained. Finally, an example shows that the values of the calculation errors for simulation value and target value (40 g) are 3.6% and 1.3%, respectively. This method can satisfy the demand for engineering accuracy.     

基于有限元法和神经网络技术的汽车碰撞事故再现

为充分利用事故变形信息,提出采用有限元法和神经网络技术进行事故再现的方法.在该方法中,首先采用数字测量技术得到事故车辆变形关键点的测量值,采用有限元仿真技术得到此关键点的计算值.将事故发生前的车辆运动参数作为神经网络的输入数据,关键点变形量测量值与仿真计算值的偏差作为神经网络的输出数据,将汽车碰撞仿真结果作为网络训练样本,对训练完成的神经网络进行优化求解得到事故发生瞬间的车辆运动参数.应用此方法对一起车-障碍物碰撞事故案例进行再现分析,建立整车、障碍物及地面有限元模型,选取前纵梁及挡泥板上的11个定位孔与螺栓孔作为变形量测量的关键点,再现分析结果验证了该方法的有效性,为事故责任鉴定提供了科学依据.