A strategy for lightweight designing of a railway vehicle car body including composite material and dynamic structural optimization

Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.

Influence of dynamic unbalance of wheelsets on the dynamic performance of high-speed cars

With further increasing in running speed of newer high-speed EMUs（electric multiple units）,higher demand for wheelset dynamic balance is required.In order to study the influence of the dynamic unbalance of wheelset on the stability,ride quality,and curving performance for a high-speed car,a detailed dynamic model of a high-speed EMU car is established using the software SIMPACK.The analysis results indicate that the dynamic unbalance of the wheelset significantly influences the dynamic performance of the high-speed car.The increase in dynamic unbalance of the wheelset will decrease the hunting critical speed,worsen the vertical ride quality,and increase the wheelset lateral force,derailment coefficient,and wheel unloading ratio.Therefore,in order to improve the stability,ride quality,and running safety of high-speed car,the values of dynamic unbalance of wheelset should be strictly controlled in manufacturing,and periodically monitored in operation.

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.

Design of lightweight magnesium car body structure under crash and vibration constraints

Car body design in view of structural performance and lightweighting is a challenging task due to all the performance targets that must be satisfied such as vehicle safety and ride quality.In this paper,material replacement along with multidisciplinary design optimization strategy is proposed to develop a lightweight car body structure that satisfies the crash and vibration criteria while minimizing weight.Through finite element simulations,full frontal,offset frontal,and side crashes of a full car model are evaluated for peak acceleration,intrusion distance,and the internal energy absorbed by the structural parts.In addition,the first three fundamental natural frequencies are combined with the crash metrics to form the design constraints.The wall thicknesses of twenty-two parts are considered as the design variables.Latin Hypercube Sampling is used to sample the design space,while Radial Basis Function methodology is used to develop surrogate models for the selected crash responses at multiple sites as well as the first three fundamental natural frequencies.A nonlinear surrogate-based optimization problem is formulated for mass minimization under crash and vibration constraints.Using Sequential Quadratic Programming,the design optimization problem is solved with the results verified by finite element simulations.The performance of the optimum design with magnesium parts shows significant weight reduction and better performance compared to the baseline design.

基于eM-Carbody平台的轿车白车身工艺规划系统

分析了轿车白车身工艺规划的需求特点,提出了基于eM-Carbody平台的白车身工艺规划系统.系统主要由三大部分构成:工艺数据模型、工艺数据模型信息提取模块以及eM-Carbody平台.依据工艺数据模型,建立零件库、资源库、操作库和工艺知识库等工艺数据库,利用工艺数据模型信息提取模块,实现工艺数据模型与eM-Carbody平台的信息互通.应用该系统成功规划了轿车左前门制造工艺,证明这一系统能很好地满足白车身工艺规划的需求.

Compact Car-Body Surface Design with T-spline Surface

Creating proper B-spline surface models is a very challenging task for designers in car-body surface design.Due to the tensor-product structure of B-spline surface,some undesirable issues of the redundant control points addition,incomplete surface definition and the difficulty of trimming boundary alteration frequently occur,when designing the car-body surface with B-spline surfaces in local-feature-lines construction,full-boundary-merging and visual surface trimming.A more efficient approach is proposed to design the car-body surface by replacing B-spline surface with classical T-spline surface.With the local refinability and multilateral definition offered by Tspline surface,those designing issues related with B-spline surface can be overcomed.Finally,modeling examples of the door,hood and rear-window are given to demonstrate the advantage of T-spline surface over B-spline surface in car-body surface design.

Fatigue test loading methodfor wagon body basedon measured load

Purpose–In this paper,the C80 special coal gondola car was taken as the subject,and the load test data of the car body at the center plate,side bearing and coupler measured on the dedicated line were broken down to generate the random load component spectrums of the car body under five working conditions,namely expansion,bouncing,rolling,torsion and pitching according to the typical motion attitude of the car body.Design/methodology/approach–On the basis of processing the measured load data,the random load component spectrums were equivalently converted into sinusoidal load component spectrums for bench test based on the principle of pseudo-damage equivalence of load.Relying on the fatigue and vibration test bench of the whole railway wagon,by taking each sinusoidal load component spectrum as the simulation target,the time waveform replication(TWR)iteration technology was adopted to create the drive signal of each loading actuator required for the fatigue test of car body on the bench,and the drive signal was corrected based on the equivalence principle of measured stress fatigue damage to obtain the fatigue test loads of car body under various typical working conditions.Findings–The fatigue test results on the test bench were substantially close to the measured test results on the line.According to the results,the relative error between the fatigue damage of the car body on the test bench and the measured damage on the line was within the range of
16.03%–27.14%.Originality/value–The bench test results basically reproduced the fatigue damage of the key parts of the car body on the line.

基于ADAMS/CAR的麦弗逊悬架优化设计

汽车悬架系统为一多体系统,部件之间的运动关系十分复杂,传统的人工计算很难将悬架的各种特性表述清楚。以国产某轿车为例,应用多体运动学与动力学仿真软件ADAMS中的CAR专业模块建立该车的前后悬架多刚体模型,对其悬架的各种性能进行了仿真分析,研究了悬架几何参数对汽车操纵稳定性的影响,在理论验证的基础上揭示了该悬架的运动规律,在进行优化分析的同时还提出了改进的意见。

车体刚强度结构优化对连发武器射击精度的影响

为减小射击时车体振动对车载连发武器射击精度的影响,建立了某轮式车辆车体有限元模型,对火炮典型射击工况下车体的受力进行了分析,以提高车体结构刚强度为优化目标,在车体后方横向增加变截面梁来改进相应的薄弱结构。车体改进前后的模态测试与射击试验结果表明,经过车体结构优化可有效改善整车环境下对射击精度影响较大的身管一阶模态频率,5连发射击时的射击精度得到有效提高。

基于正交试验法的铝合金车体高压水清洗喷嘴结构优化

抑尘剂等复杂的化合物黏着在铝合金车体上,导致车体污染十分严重,高压水射流清洗方法能够有效去除铝合金车辆车体表面黏着的化合物。通过分析圆柱形、锥形、文丘里形和余弦形喷嘴的射流流场分布、射流出口速度、最大壁面静压、相同清洗宽度下压力值范围,得到余弦形喷嘴的清洗性能最佳,锥形喷嘴次之。基于正交试验法设计五因素、四水平正交试验表,得到常用清洗压力下余弦形喷嘴的最优结构参数:进口直径为40 mm、出口直径为20 mm、过渡段半径为40 mm、出射段长度为25 mm、过渡与余弦部分长度比为4。按照最优喷嘴结构参数进行建模,得到三组压力值下高压水出射速度比未优化前提高了2%,且优化效果随着入口压力值的提高而有所下降。在优化后的喷嘴结构参数下进一步计算得出入口压力为10 MPa时,靶距设置为250 mm能达到较好的清洗效果和节能作用。

基于三维线形的轻型高速公路纵断面指标研究

为了探究轻型高速公路路线纵断面设计关键参数,基于Carsim/Trucksim软件搭建了人-车-路耦合系统,根据普遍性和不利性原则,选取轿车、面包车和轻型货车作为轻型车辆的代表性车型,开展了代表性车型在直坡路段和弯坡组合路段的行驶仿真。根据轻型车辆在纵断面和弯坡组合路段运行特征,确定了轻型高速公路的控制车型以及路线纵断面的坡度、坡长参数。结果表明:轻型高速公路纵断面设计参数应以轻型货车和面包车作为控制车型;高速行驶下,车辆在弯坡组合路段的速度衰减比在单纵坡路段更为剧烈;根据速度衰减特性和允许速度降幅,轻型高速公路设计速度为100km/h时,若允许轻型货车通行,应以比功率为25W/kg的轻型货车作为控制车辆,路线纵断面最大纵坡为5%,最大坡长为750m,若不允许轻型货车通行,路线纵断面最大纵坡为6%,可不限制最大坡长;设计速度为120km/h和140km/h时,应以比功率为35W/kg的面包车作为控制车辆,路线纵断面最大纵坡分别为6%和5%,对应的最大坡长均为1200m。

基于ADAMS/car的汽车操作稳定性建模与仿真

利用多体动力学仿真软件ADAMS建立了车辆的模型,并对汽车进行了稳态回转试验和双移线试验的设计和仿真分析.依据仿真结果,对汽车的操纵稳定性做出了评价.结果表明,利用ADAMS软件可以对汽车的操纵稳定性进行精确的仿真试验,进而达到优化产品设计方案的目的.

赛车前悬架和转向系统ADAMS/CAR建模及仿真

借助ADAMS/CAR,对某FSAE赛车双横臂独立前悬架和转向系统建立多体动力学模型,并对其进行前轮同向跳动仿真,对下控制臂球头铰上移和下移后再次仿真.仿真结果表明,下控制臂球头铰位置的变化对前轮定位参数影响显著.

地铁列车车体关键区域与车钩载荷相关性研究

为研究车钩载荷对车体关键区域的影响,文章以北京地铁某线路列车为例,阐述了列车半永久车钩静力标定试验及获得的半永久车钩应变和车钩力拟合曲线;分析了列车正线载客试验时车体关键区域测点动应力与车钩载荷的相关性,以及车钩载荷变化对各测点疲劳损伤值的贡献程度。研究表明,牵引梁端部、牵引梁车钩座旁、枕梁中心销垫板外侧焊缝、枕梁下盖板与边梁端部焊缝受车钩载荷变化的影响较大。

基于ADAMS/Car的小汽车后悬架仿真分析

以现今汽车悬架发展中具有代表性的3种悬架——拖拽臂式、双横臂式和多连杆式悬架为研究对象,通过Pro/E和ADAMS/Car联合建立多刚体动力学模型进行仿真。对比分析了3种悬架的操纵稳定性、安全性和经济性,并对3种悬架进行部分机械性能理论分析,指出了各种悬架适于应用的环境,为设计者设计和消费者选购提供理论参考和建议。

基于实车试验的大跨度桥梁轨道静态长波高低不平顺验收标准验证

由于温度、施工偏差、二期恒载等因素影响,高速铁路大跨度桥梁成桥线形与设计线形存在较大差异,且矢距差法不适用于大跨度桥梁和地基大面积沉降等区域的轨道线形验收。针对速度为250 km/h的高速铁路有砟轨道大跨度桥梁,基于轨道高低不平顺不同弦测值与车体垂向振动加速度之间的相关性,提出高低不平顺60 m弦测值与车体垂向振动加速度之间的关联关系,进而给出桥上轨道静态高低长波不平顺60 m中点弦测值10 mm的验收限值建议,最后在某主跨为672 m的高速铁路斜拉桥上预设“四峰三谷”形式的轨道高低不平顺并进行实车验证,证明此限值建议的合理性。结果表明:对于速度为250 km/h的高速铁路,车体垂向振动加速度与不平顺60 m弦测值之间呈线性关系;大跨度桥梁温度变形显著,整体表现为桥面高程与温度成反相关关系,但桥梁温度变形主要表现为长波不平顺;预设的60 m余弦波形式的轨道高低不平顺主要影响行车舒适性,对安全性影响较小,且列车速度在275 km/h及以下时,产生的车体垂向振动加速度最大值为0.98 m/s2,舒适性指标最大为2.47,评价为“优秀”,接近优秀/良好分界线。

车体涂装用PVC焊缝密封胶的研究及应用进展

汽车行业的发展对车身密封提出了更高的要求,PVC焊缝密封胶作为涂装最重要的用胶种类之一,其研究受到越来越多的关注。本文整理了近些年国内对于PVC焊缝密封胶的配方研究、施工工艺研究的公开报道以及行业研究进展,主要包括PVC焊缝密封胶的力学性能、施工性能、环保性能、施工工艺以及特殊车体要求等方面,最后进行了总结与展望。

汽车车身无痕修复技术的方法和应用

随着中国经济的发展和社会的进步,人们的生活水平也在不断提高,汽车已经成为人们日常出行的主要交通工具。汽车在使用过程中,车身磕碰是比较常见的故障,在车身损伤不大的情况下,使用传统的钣金喷漆修复,不仅费时费力,而且修复效果也不是特别好。汽车车身无痕修复技术的出现,有效解决了传统钣金喷漆修复技术存在的某些缺陷。本文首先对传统的钣金喷漆修复方式进行了简单的介绍,接着分析了汽车车身无痕修复技术的优势、方法以及应用,希望能够对汽车的车身无痕修复技术有更深层次的了解,从而推动汽车修复技术的发展。

关于汽车车身钣金修复技术的探讨

汽车车身钣金修复技术作为一种汽车修理技术手段,可以对车身的损坏部位进行修复,恢复汽车的整体性能。基于此,文章首先对汽车车身钣金修复技术的概念、特点、应用原则等进行了简单概述,接着分析了汽车钣金修复技术的重要作用以及汽车钣金修复处理中的常用技术,最后对钣金修复技术的创新路径进行了探索,旨在提升该技术的实际应用效果,推动汽车钣金修复技术的创新发展。

基于ANSYS的钢轨打磨车车体有限元分析与试验

钢轨是铁路系统中最为重要的承载部件,列车运行过程中轮轨载荷增大,波磨、疲劳裂纹、剥落等各种轨道病害日趋严重。这些轨道损伤加剧列车运行时的噪声与震动,甚至危及列车运行安全。钢轨打磨车是目前铁路公务部门钢轨修复最为有效的措施。通过打磨作业可减轻和修复钢轨损伤,改善轮轨匹配性能,延长钢轨的使用寿命,提高列车运行的平稳性和安全性。本文运用ANSYS软件对钢轨打磨车进行建模和有限元计算与分析,并将试验结果与计算结果对比,保障车体的强度与刚度满足试验标准要求,为其他车型设计积累经验。