汽车正面碰撞乘员约束系统的安全性分析

根据正面碰撞乘员约束系统的结构,简要地介绍了某车型中乘员约束系统各部件的模型的建立。并对建立好的模型进行了仿真分析,假人的伤害情况结果表明,该车型的乘员约束系统对乘员起到了很好的保护作用。     

基于正面碰撞安全性的PHEV乘员约束系统的优化和实验

以某款Plug-in混合动力电动汽车(Plug-in Hybrid Electric Vehicle,PHEV)的正面碰撞安全性为研究目标,针对设计结构和整车质量的变化可能导致原型车已经匹配好的乘员约束系统无法提供最优保护的情况,基于RBF神经网络算法,对PHEV的正面碰撞乘员约束系统的相关参数进行分析和优化,以降低假人头部、颈部和胸部的伤害值为目标,建立了PHEV的正面碰撞试验乘员约束系统仿真计算模型,通过仿真计算和实车正面碰撞试验,验证了优化后的乘员约束系统具有更好的被动安全性能。     

含乘员约束系统的轿车正面碰撞计算机模拟计算

以某车型轿车为对象建立了整车有限元模型,在此基础上集成了包括假人和安全带的乘员约束系统有限元模型.按国家标准<正面碰撞乘员保护的设计规则>规定的试验条件,对整个集成系统进行了正面碰撞的数值模拟和分析,求解出了整车的位移、速度、加速度、能量及人体模型的伤害值,实现了对该车正面碰撞过程及碰撞性能的较全面且较可靠的评价.     

轿车乘员约束系统的试验验证及参数优化

应用MADYMO模型进行虚拟试验或数值仿真是乘员约束系统开发流程中重要的方式。为得到可靠的计算结果,必需遵循规范的验证流程。详细介绍了MADYMO正面碰撞约束系统的建立和试验验证的流程。基于验证模型,进行了试验设计、参数灵敏度分析、响应面模型分析以及优化设计。优化设计结果使乘员受重伤的概率下降4.2%。在实际的工程应用中,利用MADYMO模拟可有效匹配约束系统的设计参数,达到稳健可靠的乘员保护效果。     

基于Kriging近似模型的汽车乘员约束系统稳健性设计

在汽车乘员约束系统的设计过程中,其设计变量具有一定的不确定性.传统的优化设计由于忽略了不确定因素的影响,当设计变量产生波动时,往往会导致目标超出约束边界或目标函数对设计变量的波动极为敏感,从而使设计失效.针对某款微型客车,通过乘员损伤分析软件建立该车的正面碰撞乘员约束系统仿真模型并对模型进行验证.基于该模型将试验设计、Kriging近似模型和蒙特卡罗模拟技术相结合,构造基于产品质量工程的6σ稳健性优化设计方法,实现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稳健性.工程算例表明,该方法在乘员约束系统设计方面具有较强的工程实用性.     

基于乘员损伤的汽车正面碰撞减速度波形优化

以车身减速度为研究对象,以乘员损伤指标为目标,对减速度波形进行简化并对其进行优化,为车身改进提供方向,实现车身耐撞性的正向设计。针对某款微型客车,在该车100%正面碰撞试验的基础上,利用乘员损伤分析软件建立了该车的正面碰撞乘员约束系统模型并对模型进行了验证。对该车的减速度波形进行了简化,以约束系统模型为基础,对简化减速度波形进行优化。针对特定的乘员损伤指标,优化得到了最优的车身减速度波形。为了提高计算效率,通过实验设计构建了乘员约束系统的Kriging近似模型的代替仿真模型。结果表明：该方法能更为合理地利用车身前部的压溃空间,为车身修改提供改进方向及目标,有利于车身安全性的正向设计,具有较强的工程实用性。     

Design and optimization for the occupant restraint system of vehicle based on a single freedom model

Throughout the vehicle crash event, the interactions between vehicle, occupant, restraint system (VOR) are complicated and highly non-linear. CAE and physical tests are the most widely used in vehicle passive safety development, but they can only be done with the detailed 3D model or physical samples. Often some design errors and imperfections are difficult to correct at that time, and a large amount of time will be needed. A restraint system concept design approach which based on single-degree-of-freedom occupant-vehicle model (SDOF) is proposed in this paper. The interactions between the restraint system parameters and the occupant responses in a crash are studied from the view of mechanics and energy. The discrete input and the iterative algorithm method are applied to the SDOF model to get the occupant responses quickly for arbitrary excitations (impact pulse) by MATLAB. By studying the relationships between the ridedown efficiency, the restraint stiffness, and the occupant response, the design principle of the restraint stiffness aiming to reduce occupant injury level during conceptual design is represented. Higher ridedown efficiency means more occupant energy absorbed by the vehicle, but the research result shows that higher ridedown efficiency does not mean lower occupant injury level. A proper restraint system design principle depends on two aspects. On one hand,the restraint system should lead to as high ridedown efficiency as possible, and at the same time, the restraint system should maximize use of the survival space to reduce the occupant deceleration level. As an example, an optimization of a passenger vehicle restraint system is designed by the concept design method above, and the final results are validated by MADYMO, which is the most widely used software in restraint system design, and the sled test. Consequently, a guideline and method for the occupant restraint system concept design is established in this paper.     

数控机床几何误差的综合建模与补偿

对数控机床进行误差补偿是提高数控机床加工精度的有效方法.而建立快速准确的误差模型又是实施误差补偿的前提和基础.以三轴数控机床为对象,建立综合误差模型.     

Implications of warping restraint on statics and dynamics of elastically tailored thin-walled composite beams

Static response and free vibration of elastically tailored thin-walled beams accounting for the warping restraint effect are investigated via an exact solution methodology within the context of a refined beam model. Analytical results obtained from the restrained warping model are compared with those based on its Saint-Venant model counterpart. It is revealed that the beam slenderness and thickness ratio, as well as the elastic anisotropy, considered in conjunction with the warping restraint have profound effects on the static and dynamic response characteristics. It is also shown that even for anisotropic composite thin-walled beams with high slenderness ratios, warping restraint can still be significant, implying the inadequacy of merely considering the geometric aspects in the modeling of anisotropic composite thin-walled beams.     

Buckling and collapse of cylinders with one end open and one end simply supported with varying axial restraint

This paper examines the buckling and collapse of cylindrical shells under axial load with one end radially and tangentially fixed, with varying axial fixity, and the other end free. The bifurcation loads are found for elastic cylinders, while collapse loads are found for both elastic and elastic-perfectly plastic cylinders. The varying axial restraint is applied in the form of linear springs. The eigenvalue buckling loads are calculated with conditions matching those of a classical analysis. Bifurcation loads are shown to be a function of the axial restraint; as the axial restraint is increased, the bifurcation load increases dramatically, until it reaches that of a semi-infinite, open ended cylinder. A non-dimensional form of the axial spring stiffness is proposed, and shown to be applicable across a range of geometries.The collapse load and imperfection sensitivity of cylinders with the boundary conditions examined here is also found to be a function of the axial restraint. Cylinders with low axial restraint are shown to be imperfection insensitive, with collapse loads above, or close to, the bifurcation load. As the amount of axial restraint increases, the collapse behaviour displays a degree of imperfection sensitivity associated with more usual boundary conditions.     

噪声源物理模型及抑制机理探讨

用物理模型的方法,分析机械噪声的声源、能量、声压与所对应的机械运动各参数之间的关系,为控制和改善机械噪声提出一点理论依据和抑制机理。     

基于参数化设计的麻花钻头及其仿真验证

分析了麻花钻头的加工过程,对钻头螺旋槽的成型过程中的主要参数进行了介绍.重点对钻头加工中的正问题进行研究,即对给定砂轮截面型线计算螺旋槽的端面型线,并建立了坐标系与刀片曲线的坐标方程,给出了曲线方程的详细求解过程.最后将本文的设计结果与商业软件模拟结果进行对比,结果表明在设计的线形上基本一致,细微的差别,主要是导向角不同而引起的.     

质量弹簧模型在外科模拟中的实现与应用

近些年来．对用于外科手术实时仿真算法的研究得到了飞速的发展。本文中作者首先简单地介绍和比较了目前得到广泛应用的两种用于模拟形变物体的建模方法。然后通过具体实例，笔者介绍了如何建立基于质量弹簧方法的模型以及模型的网格化。接着笔者给出了一个用于系统实时仿真的类静态模拟器的算法，包括如何对模型进行假设，以及用于简化计算的重要算法：QSS算法。最后笔者对本文做了总结，并展望了这种算法的应用前景。     

Collapse analysis of spot welded thin section members in a vehicle body structure at various impact velocities

The spot welded sections of automobiles such as the hat and double hat section members, absorb the most of the energy during the front-end collision. The purpose of this study was to analyze the collapse characteristics of spot welded section members with respect to the pitch of spot welds on flanges, through impact experiments and computation for para-closed sections and perfectly closed sections. The hat shaped section members were tested at the impact collapse velocities of 4.72 m/sec, 6.54 m/sec and 7.19 m/sec and double hat shaped section members were tested at the impact collapse velocities of 6.54 m/sec, 7.19 m/sec and 7.27 m/sec. A commercial LS-DYNA3D was used to simulate the collapse behavior of the hat and double hat shaped section members. The validity of the simulation was to be proved by comparing the simulation results and the experimental results.     

位图矢量化在模型制作中的应用

这里简单介绍了位图矢量化的概念。通过矢量化，将图像文件转换位CAM软件可以识别的图形文件，然后生成NC程序并在数控机床上加工出模型。