基于子结构和模式重复的地铁车辆座椅支架 拓扑优化

针对地铁车辆座椅模型加载范围广和座椅支架结构对称的特点,在进行地铁车辆座椅支架拓扑优化时,采用SIMP理论建立数学模型,同时引进子结构和模式重复方法,优化得到符合设计要求的结构。对比结果认为：优化后的地铁车辆座椅支架质量减轻49%,地铁车辆整体的强度性能增强,可达到地铁车辆座椅支架轻量化的目标。     

基于遗传算法的汽车仪表板横梁参数优化

节能、安全和环保是汽车工业的发展方向,汽车轻量化是实现节能减排的重要手段,以重量为目标的汽车零部件结构优化设计对减轻零件重量、提升整车性能具有重要的工程意义。以上汽通用五菱股份有限公司某车型仪表板横梁总成结构为研究对象,利用有限元分析方法对汽车仪表板横梁进行性能分析,通过正交试验方法找出对汽车仪表板横梁重量和振动性能影响较大的因素,并利用遗传算法进行结构参数优化。结果表明,在不影响各项性能的前提下,通过优化设计方法,该仪表板横梁总成减重9.96%,取得了较好的轻量化效果。     

轿车排气管挂钩刚度优化分析

针对某轿车在试车场进行耐久性试验时出现挂钩处开裂的问题,建立考虑动力总成的排气系统振动分析模型;通过频率响应分析发现挂钩开裂处的约束反力稍大,局部刚度偏低;通过结构优化使挂钩刚度得到加强.对2种优化方案的对比表明优化后的挂钩能减小排气系统传递到车身地板的振动,提高排气系统的疲劳寿命.     

增高座椅性能参数影响及损伤仿真分析

为了降低儿童乘员在碰撞过程中胸部和头部的损伤率,对增高座椅儿童约束系统进行参数化分析。本文采用多体动力学软件MADYMO建立儿童乘员碰撞仿真模型,并按照FMVSS213法规验证模型的有效性。在此基础上,以头部质心合成加速度、头部损伤准则HIC36、胸部合成加速度为损伤指标,分析增高座椅与台车座椅之间的摩擦系数、汽车座椅安全带刚度、增高座椅在高度方向上变化对儿童损伤的影响,仿真结果表明:在增高座椅底面涂以摩擦材料以提高摩擦系数,适当提高安全带刚度及维持现有座椅高度可以显著减少儿童在碰撞过程中的头部和胸部损伤。     

基于DOE和CAE技术的梯形悬置静刚度分析和优化

针对悬置系统设计过程中需要反复调整结构以满足刚度性能要求的问题,采用DOE和CAE技术对梯形橡胶悬置静刚度进行数值模拟试验,研究主簧的宽度、长度、厚度和角度等结构参数对悬置静刚度的影响,并根据试验结果进行因子分析,获得各结构参数对悬置静刚度的影响规律和相应的回归方程。运用回归方程针对实物样件目标刚度进行优化分析,能够快速获得各结构参数值,表明该方法便捷、有效,可为梯形橡胶悬置的设计制造提供参考。     

基于多模型拓扑优化方法的车身结构概念设计

为获得最优的初始设计方案,在车身概念设计阶段对车身结构进行拓扑优化。车身结构性能指标综合考虑整体刚度、局部动态刚度和碰撞性能,采用多模型优化(multi-model optimization,MMO)方法解决此类复杂工况的拓扑优化问题,通过调节设计空间和设置参数,获得车身最优载荷路径。根据拓扑优化结果初步形成车身框架结构,可为后期详细设计提供参考。     

考虑冲击载荷的汽车安全座椅碰撞防护分析

优化汽车安全座椅的碰撞防护性能,可以减少碰撞时驾乘人员的受伤程度,降低交通事故的伤亡率,为此提出冲击载荷下汽车安全座椅碰撞防护性能仿真方法。针对安全座椅零部件材料特点,构建汽车安全座椅有限元模型,利用多刚体动力学分析软件构建有限元-座椅安全带模型,通过区间二分法设定汽车初始位置、汽车安全座椅坐垫的初始状态以及分析应力情况,并通过非线性有限元动力学分析软件实行正向碰撞、侧向碰撞与后侧碰撞仿真分析。仿真结果表明,碰撞过程中假人的头部加速度、胸部加速度仿真结果与实际结果基本一致,验证了所提方法的防护性能研究结果精度较高,可以为汽车安全座椅防碰撞研究提供可靠依据。     

龙门加工中心横梁结构有限元分析与优化

本文作者通过对原型整机进行有限元分析，发现横梁结构对机床性能存在重大影响，并且是一个薄弱环节。根据筋板布置理论，采用斜支撑形式的筋板内部设计结构，结果表明新型横梁结构能有效提高整机动、静态性能。     

履带车辆乘座舒适性的建模与仿真

通过建立履带车辆"车辆-座椅-人"系统模型,并用MSC Adams软件仿真在典型路面条件下的履带车辆的垂向振动特性,对车辆乘座舒适性进行评价. 同时研究座椅的刚度、阻尼等动态参数对乘座舒适性的影响.     

基于MeshWorks和Optimus的白车身断面尺寸分析优化

为提高商用车车身前期设计阶段的开发效率,保证项目开发节点按时通过,在车身设计阶段引入参数化建模和联合仿真优化技术。基于MeshWorks软件对梁结构的整体宽度、翻边宽度、整体高度和板件厚度进行参数化建模,再通过Optimus软件搭建基于模态分析与刚度分析的优化流程,进行白车身轻量化设计。优化方案可减重14.6 kg,减重幅度5.1%,结构第1阶扭转频率提升4.4%,弯曲刚度提升2.8%,前端扭转刚度提升0.9%,后端扭转刚度提升1.5%。在性能小幅提升的情况下,车身轻量化效果明显。     

基于正碰CAE分析的车身纵梁结构优化设计

对某车型进行50 km/h、100%正面碰撞CAE仿真分析,发现车身前纵梁溃缩变形不充分,导致B柱加速度峰值超过45g目标要求。对前纵梁结构和前防撞梁吸能盒进行优化,由CAE分析可知：车身前纵梁结构变形得到明显改善,B柱加速度峰值降低到45g以下,满足目标要求。该优化可有效提高车身正面碰撞的安全性能。     

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。     

Transmission of vertical vibration through a seat: Effect of thickness of foam cushions at the seat pan and the backrest

The perception of vehicle ride comfort is influenced by the dynamic performance of full-depth foam used in many vehicle seats. The effects of the thickness of foam on the dynamic stiffness (i.e., stiffness and damping as a function of frequency) of foam cushions with three thicknesses (60, 80, and 100 mm), and the vibration transmitted through these cushions at the seat pan and the backrest were measured with 12 subjects (6 males and 6 females). With increasing thickness, the stiffness and the damping of the foam decreased. With increasing thickness of foam at the seat pan, the resonance frequencies around 4 Hz in the vertical in-line and fore-and-aft cross-axis transmissibilities of the seat pan cushion and the backrest cushion decreased. For the conditions investigated, it is concluded that the thickness of foam at a vertical backrest has little effect on the vertical in-line or fore-and-aft cross-axis transmissibilities of the foam at either the seat pan or the backrest. The frequencies of the primary resonances around 4 Hz in the vertical in-line transmissibility and the fore-and-aft cross-axis transmissibility of foam at the seat pan were highly correlated. Compared to sitting on a rigid seat pan with a foam backrest, sitting with foam at both the seat pan and the backrest reduced the resonance frequency in the vertical in-line transmissibility of the backrest foam and increased the associated transmissibility at resonance, while the fore-and-aft cross-axis transmissibility of the backrest was little affected. Compared to sitting without a backrest, sitting with a rigid vertical backrest increased the resonance frequency of the fore-and-aft cross-axis transmissibility of the seat pan cushion and increased the transmissibility at resonance.Relevance to industryThe transmissibility of a seat is determined by the dynamic properties of the occupant of the seat and the dynamic properties of the seat. This study shows how the thicknesses of foam at a seat pan and foam at a backrest affect the in-line and cross-axis transmissibilities of the foams at the seat pan and the backrest. The findings have application to the design of vehicle seats to minimise the transmission of vibration to the body.     

Bead pattern optimization

Plane sheet panels exhibit poor stiffness and NVH (noise, vibration, and harshness) performance due to their flexibility. A common and cost-effective approach in the automotive industry to improve the stiffness and NVH peformance of sheet panels is the addition of beads. However, no systematic methodology is available for determining the optimal pattern of beads in sheet metal. This research explores the feasibility of applying topology optimization methods to the bead design of sheet panels. The approach starts with adding beam elements to the shell element model of the sheet panel to simulate the stiffness improvement of the structure and then uses the topology optimization method to obtain the optimal layout of the beam elements. A cantilever plate is used to perform a preliminary study for bead pattern design and a simplified vehicle structure is used to demonstrate the applicability of the proposed method.     

Transmission characteristics of suspension seats in multi-axis vibration environments

The multi-axis vibration transmission characteristics of selected suspension seats were investigated in the laboratory. Subjects were exposed to a flat acceleration spectrum and two low frequency signals extracted from multi-axis acceleration data recorded at the floor of a passenger locomotive. Triaxial accelerations were measured at the floor of the vibration table and at the interfaces between the subject and mounted seat (seat pan and seat back). The transmission ratios between the overall seat pan and seat back accelerations and floor accelerations provided an effective tool for evaluating the effects of measurement site, vibration direction, and posture among the selected seating systems. The results showed that the system transfer matrix, estimated using a multiple-input/single-output model, would be less than ideal for predicting low frequency operational seat vibration when using suspension seats. The Seat Effective Amplitude Transmissibility (SEAT), estimated for the tested locomotive seats, was used to predict the weighted seat pan accelerations and Vibration Total Values for assessing a 1-h operational exposure in accordance with ISO 2631-1: 1997.

Relevance to industry

Multi-axis SEAT values can be estimated for seating systems tested in the laboratory using representative operational exposures. These values can be applied to monitored vehicle floor accelerations to target potentially harmful vibration in accordance with ISO 2631-1: 1997, assuming the operational exposures have similar frequency and magnitude characteristics. The transmission at the seat back should be considered when substantial low frequency multi-axis vibration is present.     

Effects of vehicle interior geometry and anthropometric variables on automobile driving posture

The effects of vehicle package, seat, and anthropometric variables on posture were studied in a laboratory vehicle mockup. Participants (68 men and women) selected their preferred driving postures in 18 combinations of seat height, fore-aft steering wheel position, and seat cushion angle. Two seats differing in stiffness and seat back contour were used in testing. Driving postures were recorded using a sonic digitizer to measure the 3D locations of body landmarks. All test variables had significant independent effects on driving posture. Drivers were found to adapt to changes in the vehicle geometry primarily by changes in limb posture, whereas torso posture remained relatively constant. Stature accounts for most of the anthropometrically related variability in driving posture, and gender differences appear to be explained by body size variation. Large intersubject differences in torso posture, which are fairly stable across different seat and package conditions, are not closely related to standard anthropometric measures. The findings can be used to predict the effects of changes in vehicle and seat design on driving postures for populations with a wide range of anthropometric characteristics.     

基于Matlab的电动汽车变速器结构优化

为满足某电动汽车整车设计中要求在有限的空间内布置变速器的需求,介绍电动汽车变速器的基本结构,建立电动汽车变速器齿轮组结构紧凑性的目标函数,在保证变速器零件强度等条件下．使变速器齿轮组和轴系的结构紧凑．运用Matlab的Optimum Toolbox对变速器结构进行优化设计,结果表明变速器的几何尺寸减小,其结构变得紧凑．     

Hybrid method for driver accommodation using optimization-based digital human models

Many applications exist where humans are required to perform a task in a seated position, such as operating a vehicle. Seated posture inside a vehicle influences driver performance and control of the vehicle. For people of extreme stature, tall or short, and for people of extreme width, obese or pregnant populations, it can be difficult to safely operate a vehicle if there is not enough room in the cab or if some controls cannot be reached. This study proposes a hybrid method for predicting the optimum driver seat adjustment range to accommodate diverse drivers in any vehicle based on a direct optimization-based posture prediction method. The proposed hybrid method combines three approaches: a boundary manikin approach, a population sampling approach, and a special population approach. The boundary manikin approach places two boundary manikins (5% female and 95% male) inside a virtual vehicle cab to perform tests. The population sampling approach spans a multitude of test subjects ranging in stature from 158 to 185 cm, determining the range from a plot of predicted hip point distances from the point of contact of the right heel and the floor. The special population approach studies the effect that size and shape changes, such as pregnancy, have on seated posture inside a vehicle. Also given is an indication of discomfort through the output values of the multi-objective function in the optimization formulation. A combination of the three approaches is used to determine an optimal adjustment range for the driver seat, thus allowing most people to safely operate the vehicle. Results of the simulations are validated using experimental determinations of the driver seat adjustment range from the literature. The main benefit of using this method is that the human aspect of design can be included early in the design process, thereby reducing or eliminating prototypes. Another benefit of the simulation is that it can be adapted to other seating tasks such as: occupant seat check inside a vehicle; workstation design; and issues related to other special populations such as obese individuals, dwarfs, and children.     

Reality of virtual damage identification based on neural networks and vibration analysis of a damaged bridge under a moving vehicle

Presented here is a reality of virtual damage detection and vibration behaviour study of a discrete beam-like bridge with one or several non-propagating edge cracks subjected to a moving vehicle. In this model, the simply supported beam elements are replaced by a range of rigid bars, which are connected by transverse and rotational springs, while the mass and rotational moment of inertia may be lumped at various points along the beam. The adopted vehicle model here is a four degrees-of-freedom, two axes half-vehicle model with tires flexibility and linear suspensions. Damage can be modelled by altering the spring stiffness equation at the crack position according to predictions, which allows the inclusion of simple or complex damage. To simplify, damage is represented here by an open crack, and stiffness of a given element with damage is calculated by fracture mechanics. Both the discrete element and finite element methods are used to investigate vibration analysis of a discrete beam model subjected to a moving vehicle to confirm model feasibility in vibration analysis under a moving vehicle. Besides, some dynamic response laws are obtained. Considering an irregular road profile, the effects of the moving vehicle velocity, the moving vehicle mass, the crack location and the crack depth on dynamic response of a beam-like bridge are analysed by a numerical example, combining a vehicle–bridge coupled vibration MATLAB program with ANSYS. In addition, the neural network is used to identify the damage of the structure. Numerical results of the numerical model predictions, compared with those obtained from the continuous elements beam, support the accuracy of the discrete elements beam model in both cases of undamaged beam and damaged one. The evidence for condition assessment and damage identification of bridge is obtained from this simulation as obtaining the vibrational characteristics of the damaged beam structure subjected to a moving vehicle. And the inversion results show that the neural network method can identify the injury location and injury size of the structure accurately.