动力总成橡胶悬置系统的动力学仿真研究

动力总成悬置系统是汽车振动系统的一个重要子系统,对改善汽车平顺性和舒适性有很大的影响。为了能够提高动力总成橡胶悬置系统的性能,该文针对某国产轿车的橡胶悬置系统,应用机械系统动力学仿真分析软件ADAMS,建立了动力总成橡胶悬置系统六自由度的动力学模型。通过对动力总成橡胶悬置系统在不同工况下的自振频率、振型、系统的能量分布、各悬置元件的平动位移和角位移的计算及分析比较,尤其将悬置元件的平动位移和角位移作为重点比较对象,讨论了悬置元件的安装角度和刚度系数对上述性能参数的影响,并得出了动力总成悬置系统的最佳方案。     

某型横向橡胶止挡结构优化设计

采用多学科优化平台Isight和参数高阶网格变形软件Sculptor对某型横向橡胶止挡进行结构形状优化设计.通过Sculptor进行参数化建模,通过Isight多目标优化算法NSGA-II获得合理的形状参数.采用Abaqus进行有限元计算,结果表明改进后的止挡垂向静刚度满足设计要求,结构设计合理.     

汽车动力总成橡胶悬置结构疲劳设计

为提高汽车悬置结构中橡胶减振件的疲劳耐久性能,定义后抗扭悬置的疲劳失效热点区域,用有限元法计算其应变分布,获得热点的最大主应变;结合橡胶材料的ε-N曲线计算结构局部疲劳寿命,运用线性疲劳累积损伤理论评估结构整体疲劳寿命.用有限元法预测的失效区域和疲劳寿命与台架强度试验得到的失效区域和疲劳寿命基本吻合,表明该结构疲劳设计方法可行。     

橡胶衬套刚度对悬架运动学的影响

橡胶衬套在现代汽车上的广泛应用对整车操纵稳定性和平顺性造成了很大的影响。为减少由于橡胶衬套引起的悬架运动学特性的变化,论文在ADAMS/View中建立了包含有橡胶衬套的麦弗逊悬架。通过ADAMS/Insight对各个衬套的刚度进行灵敏度分析,选取刚度变化对车轮定位参数影响较大的衬套刚度作为优化变量,以车轮前束角、外倾角和轮距作为优化目标。在Matlab中运用遗传算法调用ADAMS中的脚本文件,对橡胶衬套进行优化得到最优刚度值。经比较分析,优化后悬架定位参数变化范围减小。由此通过优化橡胶衬套刚度改善了悬架运动学特性。     

车辆橡胶防尘罩静力学特性分析

通过橡胶标准试件的轴向拉伸试验,得到有限元计算所需要的材料模型参数,分析了车辆防尘罩结构的刚度和强度,以及实际工况下防尘罩结构与轴杆是否存在干涉.根据橡胶产品的国家标准进行标准试样的拉伸试验,采用有限元模型中建立材料模型和建立相应的标准试样和橡胶防尘罩产品的有限元模型,并通过非线性有限元软件MSC-Marc进行了计算,得到标准试样和橡胶防尘罩产品的刚度,计算结果与原理分析吻合,从而验证了有限元计算中所建立材料模型是正确的,并对有限元软件分析的橡胶防尘罩应力分布问题.计算结果表明,能满足车辆防尘罩静力学分析的需要.     

新型低刚度减振轨道特性研究

为减小轨道交通对沿线的振动影响,提高轨道结构的减振性能,提出新型低刚度减振轨道设计方案.新型低刚度减振轨道与现有的减振轨道相比,具有更小的垂向刚度,从而降低轨道结构固有频率,提高减振性能.新型低刚度减振轨道的低刚度是由新型隔振器提供的,隔振器的弹性元件由金属橡胶元件和碟形弹簧元件构成,利用正负刚度并联的原理减小工作区间的刚度.通过ANSYS有限元软件对轨道结构和隔振器力学特性进行仿真分析,得到了不同轨道结构的结构特性和不同工况下隔振器的工作范围.结果表明,梯形轨枕结构具有较好的平均载荷的能力,证明设计的隔振器工作区间基本合理.可为低刚度减振轨道的进一步研究提供了科学依据.     

船用橡胶轴承刚度分析

为进行轴系与船体的耦合结构动力学分析,将船用橡胶轴承与轴颈的相互作用简化为以集中质量和刚度形式表述的动力学缩聚模型,并通过接触非线性有限元分析提取轴承结构的等效质量和等效刚度,准确描述含有超弹性橡胶材料的轴承结构在承受一定轴承压力下的力学行为.计算橡胶轴承结构等效质量、等效径向刚度、等效扭转刚度以及等效转动刚度等,并讨论橡胶压缩性对轴承刚度的影响.结果表明:随着橡胶可压缩性的增强,轴承的等效径向刚度增强,扭转刚度减弱.     

车门铰链系统与车门下沉刚度的相关性

针对某型车门下沉问题,通过台架试验获得车门、铰链和车身等各单因素下沉量和车门绞链系统整体下沉量,对单因素下沉量与系统整体下沉刚度进行线性拟合分析,得到车门铰链系统各单因素与系统下沉刚度的相关度排序.对前、后车门分别选取相关度较高的单因素进行优化,最终改进方案的仿真和试验结果证明该方案可有效地提升车门下沉刚度.采用定量分析法可快速找出影响下沉刚度的敏感因素,并能够快速生成优化方案,为新车型设计提供参考.     

某车型发动机悬置后支架优化设计和疲劳分析

针对某车型发动机在振动强化试验中悬置后支架出现开裂的问题,建立悬置后支架有限元模型并进行应力分析,发现应力分析结果与试验结果一致,且原支架结构应力集中现象非常明显,主要分布在侧筋根部;用OptiStruct对悬置后支架进行拓扑优化设计,结果表明拓扑优化材料应主要布置在底部和侧筋.在此基础上,通过4种优化方案的对比得到质...     

某直升机平尾有限元仿真与试验验证

为在满足静强度、刚度和疲劳寿命的条件下使直升机平尾质量最小,选取最大的设计载荷进行静强度和刚度计算,利用有限元仿真技术对平尾结构进行载荷传递的计算,确定结构的基本布局,对部件进行初步尺寸定义;利用有限元仿真技术对平尾进行详细尺寸定义.按照尺寸定义制造实物平尾,并进行静力和疲劳试验,结果表明该平尾结构的强度和疲劳性能满足设计要求.     

某型汽车悬架衬套有限元与试验分析

选取某乘用汽车悬架与导向杆之间的橡胶衬套为研究对象,在有限元软件Abaqus中建立该衬套的CAE模型,采用适当的橡胶超弹性计算方法模拟该衬套的静态加载过程,得到该衬套的静态刚度特性和应力云图,并与试验数据进行对比研究.结果表明选用合适的本构模型和超弹性参数可以得到与试验吻合度很高的数据,可以提高橡胶衬套的设计开发效率,减少试验成本.     

橡胶衬套对后扭梁悬架性能的影响分析

在Adams/Car中建立后扭梁悬架模型,通过试验设计方法找出橡胶衬套各项刚度对悬架性能影响的贡献率,得出外倾角、前束角、悬架侧倾刚度及侧倾中心随衬套刚度的变化规律,最后选取影响悬架性能最大的刚度参数作为变量因子,对不同衬套刚度取不同的比例因子,通过Adams/Insight完成优化设计分析,并确定优化后的衬套刚度值.     

重载货车轴箱弹性元件结构分析及优化

为使重载货车一系悬挂定位刚度满足铁路货运的发展要求,用Marc重点分析八字形轴箱橡胶垫结构参数的改变对其刚度的影响.根据现有线路动力学试验和理论仿真对一系悬挂定位刚度的要求,优化轴箱橡胶垫的结构参数,并分析其应力分布情况.计算结果较好地符合预期效果,有利于改进车辆动力学性能,提高使用寿命.     

复合材料磁悬浮列车车体结构数值模拟(III)——车体结构性能的参数化数值模拟

在磁悬浮列车车体参数化数值模型的基础上,开展参数变化对车体结构性能影响的数值试验,研究复合材料梁截面几何参数对车体刚度和频率的影响。在典型荷载工况下,研究关键设计参数对车体结构性能、结构部件连接模型的力学性能、车体频率和振型、车体结构线性屈曲性能的影响,确定关键设计参数对复合材料车体结构性能的影响趋势,为车体优化设计奠定基础,验证将参数化车体数值模型作为车体结构性能研究的有效性。     

Topology optimization of rubber isolators considering static and dynamic behaviours

A topology optimization for the design of rubber vibration isolators is proposed. Many vibration isolators are made of rubbers and they operate under small oscillatory load superimposed on large static deformation. Vibration isolators must have a certain degree of static stiffness in order to endure the static loading due to large gravitational and inertial forces. On the other hand, isolators must have a small dynamic stiffness in order to reduce the force transmission from vibrating systems to base structures. Therefore both the static and dynamic behaviours of rubber should be simultaneously considered in the design process. The static behaviours of rubber under large and slow loads are generally treated with hyperelastic constitutive models. Rubber under fast dynamic loads can be modelled as a viscoelastic material. In this paper, the steady state viscoelastic model, which is suggested by Kim and Youn and correctly predicts the influence of the pre-strain on the relaxation function, is applied for the dynamic analysis. The continuum-based design sensitivity analyses (DSA) of both the static hyperelastic model and dynamic viscoelastic model are developed. The topology optimization formulation is proposed in order to generate the system layouts considering both the static and dynamic performance. The density distribution approach and sequentially linear programming (SLP) are used as the optimization algorithms. Some design examples are presented in order to verify the proposed approach.     

Electromagnetic levitation micromotor with stator embedded (ELMSE): levitation and lateral stability characteristics analysis

The adhesion, friction, wear in micro system or MEMS is more significant than those in macro system. The levitation or suspension technique is one of the effective techniques to eliminate the adhesion, friction, wear caused by the surfaces contact. The electromagnetic levitation micromotor with stators embedded (ELMSE) is a kind electromagnetic eddy current levitation system, which has special structure including the double sided stator and the hollow annular rotor. Different from the electromagnetic eddy current levitation system with single sided stator, ELMSE has good stability in the vertical and lateral directions. Using the finite element method, the levitation characteristics and lateral stability characteristics are analyzed. The influence of structural parameters and electric parameters on the vertical stiffness and the lateral stiffness has been analyzed and optimized in the paper. The analysis result of the paper provides theoretical reference for the optimal design of ELMSE.     

Optimal topology design of internal stiffeners for machine pedestal structures using biological branching phenomena

Naturally evolved biological structures exhibit the optimal characteristics of light weight, high stiffness, and high strength. Based on the growth mechanism of biological branch systems in nature, an optimization method for internal stiffener plate distribution in box structures is suggested. Under the given load and support conditions, the internal stiffener plates of machine pedestal structures grow, bifurcate, and degenerate towards the direction of maximum overall structural stiffness in accordance with the adaptive growth law. The optimal and distinct distribution of internal stiffener plates with the most effective load path is thus obtained. Based on this, a size optimization for lightweight design is conducted, in which the self-weight of the structures is taken as the design objective, and the natural vibration frequency and static stiffness in the direction that is sensitive to machining accuracy are set as constraints. Finally, an optimized structure is obtained. The effectiveness of the proposed method is verified by using a precision grinder bed as an example. The results of numerical simulation and 3D–printed model experiment indicate that both the dynamic and the static performance of the optimized structure are improved, while the structural weight is reduced by compared with the initial structure. The suggested design method provides a new solution approach for the design optimization of machine pedestal structures.     

Use of structural dynamic and fatigue sensitivity derivatives in an automotive design optimization

Direct accounting for durability rarely finds its way into multidisciplinary optimization. Though reduction of loads by some means can certainly have a beneficial influence on the fatigue performance of a structure, changes in load levels are not a direct measure of the influence of design changes on fatigue performance. In this paper, a previously described method for calculating design sensitivities of a fatigue performance index is used in a simple optimization of suspension damping and stiffness on a simple truck model. The dynamic loading is a conceptual representation of the industrial practice of road testing and simulation. Results demonstrate the feasibility of using a direct measure of fatigue performance in formal structural optimization.     

Adams在橡胶轴套开裂原因分析中的应用

针对某车型麦弗逊式前悬摆臂轴套耐久试验中开裂的现象,利用Adams/Car建立前悬架模型,求出4种经典静载工况下的轴套受力并以此进行判断,同时基于多体求解的轴套受力,利用有限元法进行应力分析加以验证,确定开裂原因,为后期结构优化提供参考.