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.

Multi-objective Collaborative Optimization for the Lightweight Design of an Electric Bus Body Frame

To analyze the rollover safety,finite element models were established for the electric bus body frame,rollover simulation platform,living space,and bus rollover.The strength and stiffness of the body frame were calculated under four typical work-ing conditions considering the main low-order elastic modal characteristics.The results indicate that the initial body frame of the electric bus satisfies the required structural strength,stiffness,modes,and rollover safety,and it has great potential for lightweight design.Sensitivity and structural contribution analyses were performed to determine the design variables for lightweight optimization of the body frame,and a mathematical model was established for multi-objective collaborative optimization design of the electric bus.Then,the radial basis function neural network was used to approximate the optimiza-tion model.Besides,the accuracy of the approximate model was verified,and the non-dominated sorting genetic algorithm II was employed to determine solutions for the lightweight optimization.Compared with the initial model,the mass of the optimized model is reduced by 240 kg(9.0%)without any changes in the materials of the body frame.

Study on optimal design to improve auto-body structural crashworthiness

In this paper the optimal model of the main energy absorbed structure in an auto-body “front rail”, based on structural crashworthiness is built. For an optimal design on structure crashworthiness, the new method is based on a response surface model and Pareto GA, which improves the efficiency and flexibility of an optimal design, that is brought forward. The traditional optimal method can not be applied in the design of an impact structure due to the high nonlinearity and large time cost of crashworthiness FE analysis. So the method of an optimal design based on crashworthiness is brought forward. After constructing the response surface model of auto-body crashworthiness, the Pareto GA can be applied to find the multi-objective globally. The optimal solution set can then be used to provide many scheme combinations for choice structural parameters.To acquire the optimized structure parameters on front rail crashworthiness, this simplified model of an original design is built. After studying various ways of reinforcing the cross-section to control the structural failure mode, a better method has been found. On the precondition of not increasing the mass of the structure, an optimal design of the front rail is performed further. Finally, the optimized scheme is implemented in the full-car impact analysis and crashworthiness is studied. With proper measures to control deformation of the front rail structure the crashworthiness can be improved with minor structural modifications.

串联战斗部级间隔爆结构的研究现状和发展趋势

串联战斗部作为反爆炸反应装甲的一个重要手段,已成为国内外兵器研究的热点。串联战斗部工作时,前级装药爆炸势必对后级装药产生影响。为削弱前级装药爆炸产生的爆轰波与碎片对后级装药的影响,需要在前后级装药之间设置隔爆结构。良好的隔爆结构对串联战斗部前后级稳定工作,提升战斗部性能有重要意义。综述了近年来串联战斗部级间隔爆体的研究进展,包括结构布局、材料选型与优化设计方法等方面,并结合目前隔爆体发展状况对隔爆体未来发展趋势进行展望,以期对串联战斗部隔爆体的设计和改进有所启示。

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。

新能源汽车车身安全设计与优化研究

随着人们环境保护意识的增强及新能源汽车技术的迅猛发展,新能源汽车车身安全的设计与优化愈显重要。基于此,对新能源汽车车身安全进行设计,应充分考虑整车的结构、材料等因素,被动安全、主动安全问题,并注意与其他系统的协同。新能源汽车车身安全的优化应着眼于材料优化、结构优化与车身优化。持续提高新能源汽车的安全性能,可以使人们的出行更安全、更环保。

衍生体心立方点阵材料的优化设计及压缩力学行为

分别在传统体心立方(BCC)点阵结构(H0型)的外围以及外围和中心添加竖直杆,设计出H1型和H2型衍生BCC点阵结构,以AlSi10Mg合金粉末为原料采用激光选区熔化(SLM)技术制备出不同尺寸参数的点阵试样,研究了其压缩力学行为。结果表明:传统和衍生BCC点阵试样的压缩行为均具有线弹性阶段、平台阶段、致密化阶段等3个阶段,属拉伸主导型多孔材料;相同尺寸参数下,H2型BCC点阵试样的比强度、平台应力和单位质量吸能最大,H1型次之,H0型最小。随着单胞高度增加,H1型点阵试样的比强度和单位质量吸能基本不变,平台应力起伏略微增大,能量吸收效率小幅减小;随着单胞宽度增加,H1型点阵试样的比强度、平台应力和单位质量吸能明显降低,能量吸收效率不变;随着斜杆及外围竖直杆杆径增加,H1型点阵试样的比强度、平台应力和单位质量吸能明显增大,能量吸收效率先明显提升后趋于稳定。随着中心竖直杆杆径增加,H2型点阵试样的比强度、平台应力和单位质量吸能增大,能量吸收效率提升。衍生点阵试样的变形模式主要为由下到上的逐层变形,损伤机制为竖直杆的侧向弯曲和斜杆的垂直方向弯曲。

白车身骨架模态研究与结构优化设计

为了提高某承载式车身骨架的模态,解决其在汽车行驶过程中与外界激励频率重合产生共振和异响,改善白车身骨架的NVH性能,对某轿车白车身进行研究并对关键零部件进行了结构优化设计,并进行有限元分析验证。根据有限元分析及实车验证,这些结构优化方案对改善车身模态频率具有良好的效果,为其他车型提供设计参考。

车身工艺同步工程中的支架结构分析与优化

支架在车身产品设计中应用非常广泛,目前针对车身支架的结构分析主要集中在产品的性能评估上,而制造工况下支架结构的分析研究较少。文中提出了将有限元虚拟分析方法应用于车身工艺同步中的支架结构分析中,可在产品设计早期识别支架设计引起的制造质量风险。同时,介绍了在线冲孔、工装定位及零件安装3种工艺场景和对应的支架结构仿真方法及其结构分析仿真要求,并针对这3种工艺场景下的支架结构进行分析与优化,拓展了有限元分析在工艺同步工程中的应用场景。通过在产品早期阶段制造工程与产品工程协同,可有效识别支架在制造过程中的质量风险,避免支架在实物验证阶段更改,降低制造成本。

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.

Optimized body structure and packaging for car ODB impact performance

Front bumper,crash box and side rail are key body structural parts in front crash.Deformation space is affected by compartment packaging.The improvement suggestions are proposed to solve the problems existed in the current vehicle structure and compartment packaging based on the areas that influence performance of automobile offset deformable barrier impact, such as the side rail,mounting,storage battery packaging,etc.It is proved that 40%offset crash simulation result of one certain car is well-correlated with the physical test.Optimization cases meet the crash performance requirements.The objective of the analysis is to guide structural design and improves a car’s crash safety performance.

矿用电机械盘式制动器的结构优化与动力学分析

针对矿井提升机制动力控制问题,设计了一种能够快速响应、精确控制制动力的电机械盘式制动器。基于结构优化设计,令制动器在满足使用需求的前提下具有更轻的质量。在多柔体理论的基础上,建立了电机械制动器虚拟样机模型并进行动力学仿真。分析了制动正压力、制动间隙和制动盘转速变化。最后开展了一系列试验验证电机械制动器的工作性能,试验结果表明,电机械制动器能够精确调节制动正压力,满足制动工况的使用要求。

随钻测井仪器主基体结构强度仿真与优化设计

主基体是随钻测井仪器最重要的机械承载体。主基体上既要开槽和孔安装测量探头与电路模块,又要承受扭矩、压力、弯矩等钻井负载。槽与孔削弱了主基体的强度,也使主基体结构变得复杂。针对这一问题,引入有限元方法对基体强度进行校核,并根据计算结果优化主基体设计,增加薄弱部位承载截面面积,降低应力集中系数。优化后的基体结构安全系数满足要求。

基于拓扑优化的车身接附点结构设计

对车身接附点进行了截面简化模型的拓扑优化结构优化设计研究。以某车型前排座椅安装点结构设计为例,建立车身及座椅骨架等结构的有限元仿真模型,并进行刚度及强度性能分析,确定了相关评价指标;以安装点位置的截面作为优化对象,建立了一种车身接附点的截面简化拓扑优化模型,以安装点刚度为目标,对结构进行内部加强和外部特征的两种方式的优化设计;根据拓扑优化结果,对安装点位置截面进行了重新优化设计,共解读出4种优化方案,对比各方案得出:特征方案明显优于内部加强板方案。

基于多工况关联的无人车辆车身结构轻量化优化设计

未来战场的多样化对特种无人车辆的环境适应性提出了更高的要求。为满足特种无人车辆的多工况使用、高机动能力与低成本研制等要求,采用多工况关联设计与轻量化优化的思路对无人车桁架车身结构进行优化设计。考虑到多工况的车身结构设计变量多、设计空间大,面临仿真次数过多的问题,提出基于多工况关联的车身结构轻量化优化方法,利用设计变量区间缩减策略减小设计空间;引入高斯过程代理模型替换仿真分析实现结构设计方案性能的快速评估;结合遗传算法实现方案的优化。实验结果表明,最终优化方案在通过车身刚度强度和模态等多学科性能仿真验证的情况下,质量比初始方案降低14.12%,比只用高斯过程优化设计的方案降低8.87%。

基于PRSEUS结构的翼身融合布局后机身结构优化设计

针对翼身融合布局民机的非圆形截面机身结构承载特征,美国波音公司和美国国家航空航天局(NASA)联合提出了拉挤杆缝合高效一体化结构(PRSEUS),以提高翼身融合布局飞机机身结构的承载效率及稳定性性能。为了深入研究翼身融合布局后机身结构设计及PRSEUS结构在后机身上的应用,本文建立了基于PRSEUS结构的翼身融合布局后机身结构高保真度数值分析模型。筛选出了针对翼身融合布局后机身的5种典型载荷工况作为评估后机身结构强度和刚度的输入条件。借鉴结构区域划分技术,开展了基于PRSEUS结构的翼身融合布局后机身结构优化方法研究,完成了基于分块的PRSEUS结构后机身结构优化设计,保证了后机身结构强度和刚度性能,并进一步减轻了结构重量。

基于扭转刚度的电池包与车身集成设计研究

白车身扭转刚度是承载式车身的重要力学性能指标,对整车操稳性有着直接的影响,同时也是衡量车身轻量化水平的重要指标。由于新一代的纯电车身与传统车身有较大的结构框架差异,因此在车身设计初期,以提升扭转刚度为目标重新定义传力路径。本文基于理论分析及拓扑优化的方法找寻车身扭转刚度的最佳传力路径,通过电池包与车身的集成设计,使得车身形成多个近似圆环状的封闭结构。在车身没有增加额外质量的前提下,白车身扭转刚度可达到40000 N·m/(°),车身轻量化系数达到1.75,做到纯电车的领先水平,同时使得整车操稳性能也大幅提升。

某履带式装甲车辆铝合金车体结构仿真优化设计

为分析某型履带装甲车辆车体结构在不同射击工况下应力、位移分布情况以及最大应力点的位置,采用Altair公司开发的HyperMesh软件建立了车体有限元模型,在2种典型射击工况下对装甲车辆车体进行静强度分析,并根据静强度计算结果对刚强度薄弱部位进行结构优化改进。工况1车体最大应力值为169.3 MPa,最大位移值为2.31 mm;工况2车体最大应力值为149.6 MPa,最大位移值为2.29 mm。2种工况较优化前最大应力值均减小约20%,位移值也有所减小,车体强度完全能够满足该型履带车辆射击工况下的使用要求。

平车车体结构优化与分析

以某平车为研究对象进行静强度有限元分析,利用灵敏度分析的方法计算一阶垂弯灵敏度、位移灵敏度、质量灵敏度和应力灵敏度,并计算出对应的相对灵敏度。利用子模型技术切割整体模型,减少了优化时间和工作量。以轻量化为目标,根据相对灵敏度信息,从13个构件中选出9个构件,并以这9个构件的厚度作为设计变量对车体进行结构优化。优化后车体质量减轻1.53%,满足了车体运行的安全性。