基于分层设计变量的复合材料层合板优化设计及灵敏度分析

在复合材料层合板的结构优化设计中,提出分层设计变量的优化方法以满足实际工程需要。在结构位移、自振频率和屈曲临界荷载灵敏度分析中,给出了刚度矩阵对分层厚度和分层角度设计变量的灵敏度计算公式,考虑了分层厚度变化引起层合板对称中心的改变,保证了计算准确性。数值算例验证了灵敏度算法的精度,应用实例显示了分层设计变量方法的实用性。     

基于临界刚度的复合材料筋材多变量优化设计方法

以船舶结构优化设计为背景,针对目前结构安全余量过高导致加筋板板筋刚度过匹配现状,提出板筋刚度匹配临界刚度的概念,推导了板筋刚度比关系式。以T型复合材料筋材为对象,建立优化模型,基于Isight软件平台对设计变量进行灵敏度分析,简化设计变量。采用多岛遗传算法对筋材开展多变量优化设计,结合工程实际在筋材优化结果基础上确定设计方案,并开展复合材料加筋板力学性能试验研究,验证了多变量优化设计方法的可行性。研究表明:利用提出的加筋板板筋刚度比关系式,可以指导板筋刚度匹配设计;对T型复合材料筋材进行优化设计时,提升腹板高度对优化目标影响最明显;在等刚度约束前提下,提出的T型筋材优化设计方案能够较好地实现优化目标,同时保证了较优的经济性。      

前置后驱汽车传动系统的扭振模态分析

针对某前置后驱车,建立了其传动系的扭振当量模型,通过自由振动计算分析获得了传动系的扭振模态,与整车传动系扭振测试结果对比,验证了计算的正确性。基于传动系扭振当量模型,分析了各部件扭转刚度及转动惯量对扭振模态的灵敏度:系统第3阶扭振模态可以通过改变轮胎扭转刚度或者转动惯量来调谐;第4阶扭振模态可以使用半轴的扭转刚度、轮胎的扭转刚度或转动惯量调谐;第5阶扭振模态的调谐参数为半轴扭转刚度和传动轴转动惯量。这些因素的分析可为车辆扭转振动特性的改善提供可参考的依据。     

LET柔性铰链的等效刚度分析及其参数优化

分析了表示LET柔性铰链转动能力的扭转等效刚度,为确保铰链的转动精度提出了拉压等效刚度的概念并推导出其计算公式。以LET柔性铰链的结构参数为设计变量,提高转动能力和转动精度为目标,建立了铰链的优化模型;采用模拟退火法实现了LET柔性铰链的参数优化,并对优化前后铰链的转动性能进行了分析比较。结果表明,优化后铰链的转动能力和转动精度比优化前都有了明显提高。     

多源随机激励系统的参数灵敏度分析

采用虚拟激励法,多次利用状态空间解耦、Kronecker代数及矩阵微分理论等,推导出多源随机激励下响应均方根的参数灵敏度表达式,并将其应用于汽车平顺性分析。根据理论计算的灵敏度大小及工程实际要求,选取优化变量,对轻型货车整车模型进行了平顺性优化     

动力传动系统扭转模态及灵敏度分析

针对某款前置前驱乘用车的动力传动系统,进行了扭转模态及灵敏度的分析,使用ADAMS工程软件建立了动力传动系统模型。结合实际车型,计算了动力传动系统的固有频率、振型、扭振响应和刚度参数对系统的灵敏度。主要从调整离合器与驱动轴的刚度及阻尼,进行动力传动系统扭振的优化。这项研究为进一步分析动力传动系统零部件匹配对扭转振动的影响及改进扭振性能具有一定指导作用。     

中国科技馆磁浮展车刚-弹性动力学建模和转向架固有频率分析

以中国科技馆载人磁浮车演示车为原型,将其转向架视为刚、柔体组合,基于多体动力学整车分析,建立了11个自由度的刚-弹性车辆动力分析模型,解算了转向架的固有频率,探讨了影响转向架固有频率特性的主要参数.结果表明:转向架的扭转频率与悬挂弹簧刚度为叠加关系,扭转刚度几乎不受弹簧刚度影响;转向架相对于其它广义坐标的固有频率受悬挂弹簧刚度的影响较大;除扭转外,转向架的其它运动均有动力学耦合.     

油膜阻尼器—滑动轴承转子系统优化设计

挤压油膜阻尼器在一定程度上可以提高旋转机械系统稳定性。运用数值模拟的方法,对SFD―滑动轴承转子系统的灵敏度及动力学优化进行系统研究。研究表明：挤压油膜阻尼器间隙、轴承间隙、转轴刚度及油粘度对前两阶临界转速的影响较大,系统对这些参数的灵敏度相对较高。基于灵敏度分析得到优化的设计变量,采用遗传算法对临界转速进行了优化分析,优化目标是使工作转速尽可能远离临界转速。经过优化后,系统的临界转速得到较大改善。优化设计为提高高速转子系统的动力稳定性提供了理论基础和分析方法,从而为此类转子系统的设计提供参考。     

动车用定刚度碳纤维扭转轴设计

采用有限元辅助进行碳纤维扭转轴定刚度设计,通过碳纤维缠绕成型工艺制备碳纤维扭转轴,并进行扭转刚度测试验证.结果 表明,有限元计算得到碳纤维扭转轴扭转刚度为31.08 kN·m2/rad,实测碳纤维扭转轴扭转刚度为33.52 kN·m2/rad,设计误差为7.3％,该计算方法能够指导碳纤维扭转轴扭转刚度设计.与传统金属扭...     

基于轮心载荷的整车路噪分析与优化研究

为在设计研发阶段优化国内某型MPV汽车路面噪声问题,建立整车有限元模型。通过试验测得样车在实际道路上行驶时汽车转向节处的加速度,结合逆矩阵法、主成分分析法,利用Virtual. Lab软件求得路噪载荷激励。将该激励施加到CAE仿真模型对应位置进行计算分析,通过对比实测数据验证仿真建模的有效性。并基于整车模型进一步分析底盘关键部件对车内声压的灵敏度,依据分析结果,给出调整前副车架刚度、前控制臂刚度、前减震器衬套刚度以及后车架刚度等的解决方案包。优化后车内噪声各频率峰值均有明显降低,分贝值平均降低4.4 dB(A),对于缩短该型MPV开发周期和降低生产成本具有重要参考意义。     

Lightweight design of bus frames from multi-material topology optimization to cross-sectional size optimization

A comprehensive solution for bus frame design is proposed to bridge multi-material topology optimization and cross-sectional size optimization. Three types of variables (material, topology and size) and two types of constraints (static stiffness and frequencies) are considered to promote this practical design. For multi-material topology optimization, an ordered solid isotropic material with penalization interpolation is used to transform the multi-material selection problem into a pure topology optimization problem, without introducing new design variables. Then, based on the previously optimal topology result, cross-sectional sizes of the bus frame are optimized to further seek the least mass. Sequential linear programming is preferred to solve the two structural optimization problems. Finally, an engineering example verifies the effectiveness of the presented method, which bridges the gap between topology optimization and size optimization, and achieves a more lightweight bus frame than traditional single-material topology optimization.     

基于刚度和模态灵敏度分析的轿车车身轻量化研究

以某轿车白车身为例,建立有限元模型,以车身结构的刚度和模态有限元计算为基础,经灵敏度分析方法确定优化设计变量,以车身结构质量的最小化为目标,在保证车身刚度和模态性能的前提下,优化车身零件的厚度,从而实现车身结构的轻量化,车身减轻的重量为原来的3.6%,车身结构的刚度和主要模态频率也都获得不同程度的提高。     

基于模态灵敏度分析的客车车身优化

针对提高国产某轻型客车的乘坐舒适性,解决车内振动和噪声剧烈问题,本文首先基于有限元仿真和道路试验的阶次跟踪方法进行振动和噪声原因分析,所确定的原因为轮胎激励引起的车身结构共振。为避免共振,以白车身钣金件和骨架的厚度为设计变量,以提高白车身前两阶固有频率为目的,用模态灵敏度理论对白车身进行优化设计和灵敏度分析。然后结合各钣金件和骨架的模态灵敏度和质量灵敏度,设计最优的改进方案并进行试验分析。对比优化前后的试验结果,验证了该优化方案的有效性与合理性。     

缓冲包装设计的灵敏度分析

首次对非线性多自由度包装结构缓冲设计进行了灵敏度分析。根据摄动法得到渐近解,通过脉冲响应及其关于设计变量的灵敏度表示成积分形式,该方法适用于质量阵、阻尼阵和刚度阵非对称及非比例阻尼的条件。利用响应灵敏度表达缓冲性能极值关于设计变量的灵敏度。通过其灵敏度分析进行改进能有效地提高缓冲性能。     

The spur planetary gear torsional stiffness and its crack sensitivity under quasi-static conditions

The sun–planet and ring–planet tooth mesh stiffness variations and the resulting transmission errors are the main internal vibration generation mechanisms for planetary gear systems. This paper presents the results of torsional stiffness analysis of involute spur planetary gear systems in mesh using finite element methods. A planetary gear model with three planet gears and fixed ring gear and its subsystem models have been developed to study the subsystem and overall torsional stiffnesses. Based on the analysis of torsional mesh stiffness, predictive models for single branch sun–planet–ring and overall planetary gear torsional stiffnesses have been proposed. A crack coefficient was introduced to the sun–planet and ring–planet meshes to predict the effect and sensitivity of changes to the overall torsional mesh stiffness. The resulting mesh stiffness crack sensitivity of the overall gear system was analysed under quasi-static conditions. It was found that the carrier arm stiffness has great influence on the crack sensitivity while the overall stiffness was most sensitive to the crack on the sun–planet mesh.     

Optimum Design of Composite Sandwich Structures Subjected to Combined Torsion and Bending Loads

This research is motivated by the increase use of composite sandwich structures in a wide range of industries such as automotive, aerospace and civil infrastructure. To maximise stiffness at minimum weight, the paper develops a minimum weight optimization method for sandwich structure under combined torsion and bending loads. We first extend the minimum-weight design of sandwich structures under bending load to the case of torsional deformation and then present optimum solutions for the combined requirements of both bending and torsional stiffness. Three design cases are identified for a sandwich structure required to meet multiple design constraints of torsion and bending stiffness. The optimum solutions for all three cases are derived. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins.     

SENSITIVITY ANALYSIS BASED ON THE FORCE METHOD FOR DEPLOYABLE CABLE-STIFFENED STRUCTURES

The force method is an ideal structural analysis tool when dealing with prestress and internal mobility. This paper presents a sensitivity analysis for the internal forces and nodal displacements of a structure with respect to key design variables such as structural configurations, member cross-sectional areas and material parameters, etc, this analysis, though limited to small displacements and rotations of liner elastic structures, provides a useful tool in the structural design process for tasks such as minimizing weight, maximizing stiffness or achieving a better distribution of prestress. The method proposed is applied to the optimization of a cable-stiffened deployable mast, where the lowest mass has been sought subject to a given stiffness requirement.     

不同截面梁构件的刚度和稳定性优化设计

本文运用有限元分析与优化设计软件JIFEX，对五种常用截面梁结构的尺寸和形状进行了抗剪、抗弯、抗扭的刚度优化设计和在轴力、剪力作用下的结构稳定性优化设计。通过对优化设计的计算结果分析，得到了对工程设计有意义的若干结论。然后通过飞机结构中一种波形梁构件的优化，进一步讨论了波形梁的波数对结构稳定性和刚度的影响。