薄壁梁诱导槽结构抗撞性优化设计及应用

通过分析各种变形诱导结构设计特点的基础上,提出了一种有效的变形诱导槽结构.将该变形诱导槽结构应用于某车架前纵梁的碰撞模拟中,以提高其动态吸能特性.选取前纵梁诱导结构的主要设计参数作为研究对象,采用响应面法并结合正交试验设计、显式有限元方法等来进行分析.建立了前纵梁诱导结构的总吸能和最大冲击载荷的多目标优化模型,并对模型...     

一种平台化小偏置碰撞结构优化设计方法

基于避能结构设计理念,设计了以环形吸能结构(Energy Absorbing Ring)为代表的传力吸能结构,通过对某SUV进行碰撞区域划分,设计正交试验,利用仿真计算结果建立了高精度响应面模型,得到不同碰撞区域的传力分布及吸能匹配的优化方案,并进行正面碰撞工况仿真验证.结合平台化开发特征,对与该SUV同平台的MPV车...     

为提高低速碰撞性能的轿车保险杠吸能盒结构优化

建立了吸能盒低速碰撞性能的评价模型,提出了一种集成有限元模拟和序列响应面法的优化方法.为保证优化过程的收敛,采用信赖域模型管理策略来调整设计空间.与传统的基于梯度的优化方法相比,该方法计算量小,结果准确.最后给出了某轿车后保险杠吸能盒结构优化实例,验证了该方法的可靠性.     

基于耐撞性的前纵梁焊点模拟及其优化设计

建立了3种焊点有限元模型,并通过薄壁梁(代表前纵梁)落锤试验,验证其模拟精度。结果表明,Beam单元最适合碰撞过程中焊点的模拟。分析了焊点失效对耐撞性的影响,同时采用试验设计和响应面法,对薄壁梁的几何参数和焊点位置进行了优化。结果提高了耐撞性,减小了焊点失效的风险。实车试验证明了该方法的合理性。     

碳纤维复合材料防撞梁轻量化设计

为某车型设计了碳纤维复合材料防撞梁,建立了其有限元分析模型,并用传统钢制防撞梁碰撞试验与仿真结果对比验证了模型准确性。然后采用全因子实验设计确定其横截面形状与铺层顺序的最优组合,最后应用NSGA-Ⅱ遗传算法对防撞梁结构铺层厚度进行了多目标优化。结果表明,在其碰撞性能提高的基础上,轻量效果达到将近65%,且优化后的防撞梁结构与吸能盒和前纵梁结构连接后,在高速碰撞过程中变形模式更合理。     

桥梁结构有限元模型的仿射-区间不确定修正

为获得桥梁结构的基准状态，考虑测试和结构参数的不确定性，将区间分析、仿射算法引入响应面有限元模型修正方法中，建立了一种新的桥梁结构有限元不确定模型修正方法。在讨论结构特点及力学行为的基础上，选择了待修正结构参数和结构响应后，采用均匀试验设计方法获得试验样本，同时结合多样本的有限元分析，采用F检验法得到结构响应的显著性参数。基于有限元模型修正的响应面方法，构建结构的响应面替代模型后，引入区间分析算法的自然拓展，将响应面模型拓展为区间响应面函数，同时采用仿射算法解决区间分析的区间扩张问题，构建桥梁结构有限元模型的仿射-区间不确定修正方法，并采用遗传算法进行区间优化求解。另外，针对区间响应面有限元模型修正的具体需求，提出了区间响应面函数的两步验证方法。用斜拉桥振动台模型桥梁在不同工况下的测试模态参数和斜拉索索力，对其进行有限元模型的不确定修正，实现了实测响应与有限元计算响应间误差的最小化。区间响应面函数的两步验证证实了参数修正范围和结构响应的有效性和正确性，修正后结构纵向、横向、竖向的一阶，二阶频率以及索力的实测响应均在计算响应范围内。验证结果表明：所提有限元不确定模型修正方法，能有效实现桥梁结构有限元模型的修正。     

基于E-NCAP的10岁儿童损伤防护研究

最新版欧洲新车评价规程(E-NCAP)使用10岁Q系列儿童假人来评价约束系统对儿童乘员的保护效果。针对某国内量产车型,分别采用MADYMO和Hypermesh软件建立了该车的后排6岁儿童乘员约束系统仿真模型和整车有限元模型,并利用试验数据进行了对比验证。将Q10儿童假人放入已验证的儿童约束系统中,根据E-NCAP规定的正面40%偏置碰撞和侧面碰撞要求进行仿真。在对两种工况下乘员约束系统参数灵敏度分析的基础上,选取对儿童损伤影响显著的参数为优化变量,以综合评价损伤指标WIC最小为优化目标,采用Kriging算法创建响应面模型并结合遗传算法进行参数优化。结果表明:优化后的约束系统参数能有效提高对10岁儿童乘员的保护效果,正面偏置碰撞中得分提高了24.6%,侧面碰撞中得分提高了36.5%。     

基于抗撞性和设计空间的薄壁直梁参数优化

运用碰撞仿真技术,对能够代表汽车前纵梁的6种薄壁直梁进行了截面形状选择;针对所选取的较优截面形状直梁的截面尺寸、板厚和材料强度进行了正交试验设计,以吸能、比吸能和压溃距离为主要评价指标建立了响应面模型并进行优化.结果表明,优化后的直梁在质量仅增加3.2％的情况下,不仅抗撞性明显提高,而且设计空间下降了约27.1％.     

基于代理模型的薄壁钣件抗撞性优化设计

为研究薄壁吸能钣件的抗撞性,基于动力显式有限元法和全因子试验设计,结合响应面方法建立了薄壁钣件的代理模型.以结构的比吸能为优化目标,采用序列二次规划算法对结构参数进行优化,找到吸能钣件的比吸能随钣件长度和厚度而变化的规律,得到了该薄壁钣件的最优设计参数.     

材料参数对车身吸能元件抗撞性影响的数值分析

基于数值分析方法研究了材料参数对车身薄壁吸能构件抗撞性的影响.以材料参数为变量,选取多个离散的设计点,用显式有限元分析,求得这些点的比吸能;采用响应面法建立了表示比吸能随材料参数而变化的曲面,和高次多项式拟合时的相对误差曲线.最后给出了有限元分析得到的构件轴对称叠缩变形图,与试验结果吻合很好,表明响应面法与显式有限元技术相结合的方法可行有效.     

车身碰撞仿真技术在红旗轿车车身开发中的应用

汽车被动安全国内研究大多集中在实车检测方面。本文介绍了红旗轿车车身开发中应用高度非线性有限元方法对车身结构碰撞历程进行数值仿真研究工作的概况。通过对基本结构件的研究弄清计算方法和参数,通过对车身主要吸能结构元件仿真计算研究,找出合理的技术参数,为全车身碰撞计算提供依据。在这些工作基础上成功地进行了红旗轿车车身碰撞计算。与实车碰撞实验结果相比,吻合较好,对红旗轿车前纵梁组件不同设计结构方案能量吸收性     

基于多目标模拟退火算法的高速电磁阀优化设计

高速电磁阀的关键结构参数对高压共轨喷油器的响应特性具有决定性影响,采用多目标模拟退火优化算法MOSA(Multi Objective Simulated Annealing),基于多目标多学科优化平台modeFrontier,并集成有限元分析软件Ansys,以高速电磁阀开启、关闭延迟时间和电磁力为目标函数建立了多目标优化模型,对高速电磁阀的关键结构参数进行多目标优化设计。结果表明:电磁阀开启延迟时间降低了15.4%,达到0.11 ms;关闭延迟时间降低了25%,达到0.18 ms,;电磁力提高了12.5%,达到160 N。     

Optimizing the shape of a bumper beam section considering pedestrian protection

This paper presents a design technique to optimize the shape of a vehicle bumper beam that satisfies both the safety requirements for a front rigid-wall impact and the regulations protecting pedestrians from lower leg injuries caused by bumper impacts. An intermediate response surface modeling (IRSM) technique was introduced to approximate the non-linear force-displacement curves obtained from the front impact analysis of a vehicle bumper. The accuracy of the IRSM model was tested by comparing its results with those of the non-linear finite element analysis. The maximum displacement error between the two models did not exceed 3%. Using pedestrian impact analyses based on the experimental arrangement of the Plackett-Burman design, the approximate functions describing the response values acting on the lower legs were calculated. The shape of the bumper beam was optimized by integrating the IRSM with the force-displacement model and the approximate functions on lower leg impact. The optimization results satisfied safety regulations on the maximum allowable displacement of the vehicle bumper, and also the regulations protecting pedestrians from lower leg injuries caused by bumper impacts.     

Comparison of the optimum designs of center pillar assembly of an auto-body between conventional steel and ahss with a simplified side impact analysis

This study compares the optimum designs of center pillar assembly with advanced high-strength steel (AHSS) to that of conventional steel for crashworthiness and weight reduction in side impacts. A simplified side impact analysis method was used to simulate the crash behavior of the center pillar assembly with efficient computing time. Thickness optimization aims to perform an S-shaped deformation of the center pillar toward the cabin to reduce the injury level of a driver in a crash test. Center pillar members were regarded as an assembly of parts that are fabricated with tailor-welded blanks, and the thickness of each part was selected as a design variable. The thickness variables of parts that have significant effects on the deformation mechanism were extracted as the main design variables for thickness optimization based on the results of a sensitivity analysis with design of experiments. The optimization condition was constructed to induce an S-shaped deformation mode and reduce the weight of the center pillar assembly. An optimum design was obtained after several iterations with response surface methodology (RSM). Optimization was first performed with conventional steel and then with AHSS with the same procedure to optimize the crashworthiness of the center pillar assembly. After thickness optimization, optimum designs were applied to the full vehicle analysis to evaluate the validity of the optimization scheme with the simplified side impact analysis method. Then, the crashworthiness of optimum designs with conventional steel and AHSS were compared using the full vehicle analysis. This comparison demonstrates that AHSS can be more effectively utilized than conventional steel to obtain a lightweight design of an auto-body with enhanced crashworthiness.     

基于响应面法的钢-混组合桥面系优化设计

对桥梁结构进行优化设计和可靠性研究时,采用传统的设计方法可能会遇到计算工作量繁重的问题,应用响应面法进行优化设计是有效解决该问题的途径之一。以某大跨悬索桥钢-混组合桥面系为研究对象,结合节段缩尺模型试验研究,以有限元软件Workbench为计算平台,建立相应的参数化有限元模型。以组合桥面系重量最轻为经济目标,最大变形及最大弯曲应力为约束,基于响应面法对其进行多参数优化设计,并对优化结果进行了有限元分析验证。计算结果表明:节段缩尺模型静力试验结果与有限元分析结果吻合较好,建立的有限元模型很好地反映了试验模型实际的受力状态;基于响应面法优化设计后组合桥面系质量减小了3.57%,在满足力学性能要求的同时,减轻了结构自重,降低了工程造价,为钢-混组合桥面系设计提供了良好的概念设计模型。     

基于动载试验的变截面桥梁静载试验结果预测方法研究

为了解决既有桥梁荷载试验成本高、对交通影响大以及容易对桥梁结构造成损伤等诸多问题,提出基于廉价安全的动载试验数据,利用响应面方法对既有桥梁的实际刚度进行智能分析预测,从而达到高精度预测既有桥梁静载试验结果的目的。为实现上述目标,选取典型连续变截面刚构桥作为研究对象,尝试将桥梁主梁变截面参数化,对桥梁关键设计参数进行敏感性分析,并且建立Kriging响应面模型,实现对有限元模型的高精度修正。研究结果表明:基于Kriging模型的有限元模型修正方法能够利用桥梁动载测试结果对初始设计参数进行修正,并进一步预测静载试验结果;该方法成本低廉,对交通影响小且安全性高,这将节省大量的桥梁静载试验费用,同时能够对桥梁的静力行为进行全方面有效的分析和预测。研究结果可为既有桥梁工程的管养维护决策提供新的思路。     

A dynamic wheel–rail impact analysis of railway track under wheel flat by finite element analysis

Wheel–rail interaction is one of the most important research topics in railway engineering. It involves track impact response, track vibration and track safety. Track structure failures caused by wheel–rail impact forces can lead to significant economic loss for track owners through damage to rails and to the sleepers beneath. Wheel–rail impact forces occur because of imperfections in the wheels or rails such as wheel flats, irregular wheel profiles, rail corrugations and differences in the heights of rails connected at a welded joint. A wheel flat can cause a large dynamic impact force as well as a forced vibration with a high frequency, which can cause damage to the track structure. In the present work, a three-dimensional finite element (FE) model for the impact analysis induced by the wheel flat is developed by the use of the FE analysis (FEA) software package ANSYS and validated by another validated simulation. The effect of wheel flats on impact forces is thoroughly investigated. It is found that the presence of a wheel flat will significantly increase the dynamic impact force on both rail and sleeper. The impact force will monotonically increase with the size of wheel flats. The relationships between the impact force and the wheel flat size are explored from this FEA and they are important for track engineers to improve their understanding of the design and maintenance of the track system.