地铁车辆吸能装置耐碰撞性分析

吸能装置是确保地铁列车具有良好耐碰撞性能的一种重要部件.为实现地铁车辆吸能装置的结构优化,采用有限元分析软件ANSYS/LS-DYNA对不同厚度、不同横截面形状的薄壁结构碰撞性进行了仿真分析,分析结果表明,吸能装置的性能与其横截面的形状、壁厚的选择紧密相关.条件相同时,吸能装置的吸能能力与壁厚成正比,但壁厚增加时,界面力也随之增大,在吸能结构的设计中,需综合考虑.以地铁头车为研究对象,对安装了吸能装置的地铁头车进行了碰撞仿真,得到车体吸能装置碰撞过程变形情况和碰撞能量-时间历程,结果表明该结构吸能装置具有良好的吸能特性.     

内凹三角形负泊松比结构耐撞性多目标优化设计

为设计出具有良好耐撞性的车辆碰撞吸能结构,以内凹三角形负泊松比多胞结构为研究对象,通过显式动力有限元软件LS-DYNA建立了此吸能结构的轴向冲击有限元模型。结合最优拉丁超立方设计方法,构建了此吸能结构的峰值冲击力PCF和比吸能SEA关于长胞壁尺寸a与胞壁厚度b的多项式代理模型,采用第二代非劣排序遗传算法(NSGA-II)进行多目标优化设计,并基于适应度函数C获取一妥协解。优化结果表明:胞壁厚度比长胞壁尺寸对此吸能结构耐撞性影响更显著,通过合理匹配壁厚和长胞壁长度,能有效降低峰值冲击力,提高比吸能。     

考虑汽车正面低速碰撞角度偏差的 吸能盒性能优化设计

汽车发生正面低速碰撞时,由于各种因素的影响,不能达到百分之百的正面碰撞。因此,运用非线性有限元LS-DYNA仿真软件对碰撞方向偏差±6°的汽车正面低速碰撞进行了仿真模拟,在确保吸能盒在正面碰撞过程中能够吸收一定能量的基础上,当汽车的碰撞角度发生偏差时也能够使吸能盒具有良好的吸能效果,保障车辆与乘员安全。并通过定义目标优化函数及仿真研究进行了吸能盒优化设计,得到优化后吸能盒的碰撞吸能数值及碰撞角度变化时碰撞吸能的变化情况,从而得出具最佳吸能性能吸能盒的设计变量,即吸能盒壁厚1.5 mm、长180 mm、边数为6,此结构下在碰撞角度偏差±6°时,其T值最小。     

兼顾轻量化与吸能性的汽车前纵梁拼焊板设计与参数优化

为减轻车身质量，减少冲压模具数量和降低制造成本，采用拼焊板对某小车的主要吸能部件前纵梁进行了改进设计，并对各块差厚钢板的材料等级及厚度进行了正交试验优化．为保证整车正面碰撞中前纵梁的吸能性，将该梁在整车有限元模型中进行替换，并按照法规及C-NCAP要求进行了正面碰撞分析．结果表明：替换后其碰撞吸能量上升2％左右，B柱的一侧加速度峰值平均下降3％以上，但该零件的质量却降低了6％左右．     

兼顾轻量化与吸能性的汽车前纵梁拼焊板设计与参数优化

为减轻车身质量,减少冲压模具数量和降低制造成本,采用拼焊板对某小车的主要吸能部件前纵梁进行了改进设计,并对各块差厚钢板的材料等级及厚度进行了正交试验优化.为保证整车正面碰撞中前纵梁的吸能性,将该梁在整车有限元模型中进行替换,并按照法规及C-NCAP要求进行了正面碰撞分析.结果表明:替换后其碰撞吸能量上升2%左右,B柱的一侧加速度峰值平均下降3%以上,但该零件的质量却降低了6%左右.     

基于响应表面法的分级吸能结构优化设计

设计了一款由3层方管组成的分级碰撞吸能结构。为得到吸能结构的最优方案,运用正交试验法从27种设计方案中确定了9个试验样本,并通过非线性有限元法对其碰撞吸能过程进行了仿真分析。在此基础上,应用响应表面法得到吸能结构参数与吸能评价指标的非线性映射关系。通过优化得到了最佳方案,明显提高了方案优选效率和吸能能力。     

基于低速碰撞试验的吸能支架拓扑优化设计

介绍了拓扑优化方法的基础理论知识,提出吸能支架的等效模型及理论计算方法。借助Optistruct软件,对保险杠吸能支架进行拓扑优化,设计出合理的吸能支架截面形状,解决了吸能支架在碰撞力作用下向外弯曲偏移的问题。通过低速碰撞试验证明了结构设计的合理性。     

基于汽车正面碰撞的吸能盒设计及优化

对汽车正面碰撞有限元模型进行了分析,建立了可替代整车碰撞模型的子模型,并对其进行验证。在所建立的子模型的基础上,设计出了双层波纹管样式的吸能盒结构,利用自适应响应面法对其厚度进行优化设计。整车碰撞仿真结果表明:吸能盒结构吸收的能量比原结构提高了14.2%,纵梁碰撞力比原结构减小了15.3%。     

仿荷薄壁管的耐撞性研究

针对传统薄壁圆管结构存在的问题,本文采用结构仿生原理,主要对仿荷薄壁管在轴向冲击下的耐撞性进行研究。利用有限元分析软件对薄壁管做碰撞仿真,以比吸能和峰值力为评价指标,结合不同薄壁管在碰撞时发生的变形模式,分析3组仿荷薄壁管的轴向吸能特性。仿真结果表明,仿荷薄壁管较普通圆管有更好的吸能特性;在比吸能指标方面,3组结构同一系列的仿荷薄壁管比吸能为:B组C组A组,B组结构的比吸能提升最高,比A组平均提升20%;在峰值力指标方面,同一系列的B组仿荷薄壁管较A组仿荷薄壁管的峰值力也有所提升,C组仿荷薄壁管的峰值力受胞数增加的影响最大,当胞数增加到7以上时,C组峰值力大于B组,在不影响吸能的情况下,减小碰撞过程中产生的峰值力,可以保护车内乘员的安全,说明B组仿荷薄壁管是一种更合理的吸能结构。该研究在汽车数值结构分析与优化设计中具有广阔的应用前景。     

基于响应面法的车门防撞梁多学科设计优化

对车门防撞梁的原始设计方案进行优化,以M形截面车门防撞梁替代原管型防撞梁的设计方案,并以M形截面车门防撞梁的材料参数作为设计变量,以提高车门防撞梁的轻量化性能及其在侧面碰撞中的吸能性为优化目标,采用正交试验设计方法进行样本数据设计,使用响应面法建立车门防撞梁轻量化性能及吸能性的多学科近似模型,通过遗传法最终得到最优的车门防撞梁材料方案,在保证其质量不增加的情况下,显著提高了车门防撞梁的碰撞吸能性.     

参数化诱导槽设计的吸能盒结构抗撞性多目标优化

针对车身前部抗撞部件吸能盒结构的常见的方形截面薄壁锥管,研究了其在低速冲击工况下的最佳抗撞性能模型优化。将压溃力效率及比吸能作为评价指标,建立加权组合形式的多目标优化模型。分析研究分布设置诱导槽对结构吸能与压溃力的影响,选择诱导槽设定的可行区域。以槽的个数、非均匀分布的槽间距离及槽的深度等作为优化参数,合理选取样本点后,分别应用三次多项式响应面法及径向基法构建其有效代理模型,并采用粒子群法进行优化设计,得出使结构最优的诱导槽位置分布及数量。仿真分析验证了本文方法的有效性。     

Multi-objective robust design optimization of a novel negative Poisson’s ratio bumper system

Negative Poisson’s ratio (NPR) structure has outstanding performances in lightweight and energy absorption, and it can be widely applied in automotive industries. By combining the front anti-collision beam, crash box and NPR structure, a novel NPR bumper system for improving the crashworthiness is first proposed in the work. The performances of the NPR bumper system are detailed studied by comparing to traditional bumper system and aluminum foam filled bumper system. To achieve the rapid design while considering perturbation induced by parameter uncertainties, a multi-objective robust design optimization method of the NPR bumper system is also proposed. The parametric model of the bumper system is constructed by combining the full parametric model of the traditional bumper system and the parametric model of the NPR structure. Optimal Latin hypercube sampling technique and dual response surface method are combined to construct the surrogate models. The multi-objective robust optimization results of the NPR bumper system are then obtained by applying the multi-objective particle swarm optimization algorithm and six sigma criteria. The results yielded from the optimizations indicate that the energy absorption capacity is improved significantly by the NPR bumper system and its performances are further optimized efficiently by the multi-objective robust design optimization method.     

Parametric design strategy of a novel cylindrical negative Poisson’s ratio jounce bumper for ideal uniaxial compression load-displacement curve

A cylindrical negative Poisson’s ratio (CNPR) structure based on two-dimensional double-arrow negative Poisson’s ratio (NPR) structure was introduced in this paper. The CNPR structure has excellent stiffness, damping and energy absorption performances, and can be applied as spring, damper and energy absorbing components. In this study, the CNPR structure was used as a jounce bumper in vehicle suspension, and the load-displacement curve of NPR jounce bumper was discussed. Moreover, the influences of structural parameters and materials on the load-displacement curve of NPR jounce bumper were specifically researched. It came to the conclusion that only the numbers of cells and layers impact the hardening displacement of NPR jounce bumper. And all parameters significantly affect the structure stiffness at different displacement periods. On the other hand, the load-displacement curve of NPR jounce bumper should be in an ideal region which is difficult to be achieved applying mathematical optimization method. Therefore, a parametric design strategy of NPR jounce bumper was proposed according to the parametric analysis results. The design strategy had two main steps: design of hardening displacement and design of stiffness. The analysis results proved that the proposed method is reliable and is also meaningful for relevant structure design problem.     

预测合金固溶度的A-I图

单壳船舷侧结构填充设计及其性能仿真

甘浪雄^1,2, 李慧^1,2,3, 张磊^1,2, 周春辉^1,2, 郑元洲^1,2, 赵晓博⁴

（1.武汉理工大学 航运学院,武汉 430063; 2.内河航运技术湖北省重点实验室,武汉 430063; 3. 长江航运发展研究中心,武汉 430014; 4.中华人民共和国南京海事局,南京 210011）

创新点说明：

基于蜂窝式夹层板、折叠式夹层板及圆管式夹层板理论提出三种特殊的单壳耐撞结构形式,利用非线性有限元软件MSC. Dytran对三种特殊夹层板单壳结构的吸能特性、损伤变形等进行数值仿真分析,并与常规单壳舷侧结构进行比较和分析。为以后船舶舷侧碰撞性能的评估及未来新型船舶结构的耐撞性优化设计提供借鉴。

研究目的：

为提高舷侧结构的耐撞性能,通过对常规舷侧结构进行改进,提出一种新型高效的吸能舷侧结构来实现。

研究方法：

数值计算和数值仿真法。其中,有限元建模使用了软件Solidworks,Cad和MSC.Patran ;有限元仿真使用了软件MSC.Dytran和Matlab。

研究结果：

数值仿真结果表明,夹层板舷侧结构显著提高了舷侧结构的耐撞能力,是一种先进的船舶防护结构形式,且圆管式夹层板结构效果最显著。

结论：

研究成果可为以后船舶舷侧碰撞性能的评估及未来新型船舶结构的耐撞性优化设计提供借鉴。

关键词：舷侧结构,防撞性,填充层,船舶碰撞

     

Grey Relational Analysis Coupled with Principal Component Analysis Method For Optimization Design of Novel Crash Box Structure

Crashworthiness and lightweight optimization design of the crash box are studied in this paper. For the initial model, a physical test was performed to verify the model. Then, a parametric model using mesh morphing technology is used to optimize and decrease the maximum collision force (MCF) and increase specific energy absorption (SEA) while ensure mass is not increased. Because MCF and SEA are two conflicting objectives, grey relational analysis (GRA) and principal component analysis (PCA) are employed for design optimization of the crash box. Furthermore, multi-objective analysis can convert to a single objective using the grey relational grade (GRG) simultaneously, hence, the proposed method can obtain the optimal combination of design parameters for the crash box. It can be concluded that the proposed method decreases the MCF and weight to 16.7% and 29.4% respectively, while increasing SEA to 16.4%. Meanwhile, the proposed method in comparison to the conventional NSGA-Ⅱ method, reduces the time cost by 103%. Hence, the proposed method can be properly applied to the optimization of the crash box.     

基于MOPSO算法的斜拉桥索力优化分析

针对斜拉桥设计和监控计算中合理成桥状态和施工状态索力的确定问题,提出了一种基于MOPSO算法的斜拉桥索力优化方法。该方法在PSO算法的基础上通过增加外部储备集和优化更新策略来适应多目标、多约束的索力优化,较单目标优化方法仅有单一解的局限性,MOPSO算法考虑因素更全面,得到的Pareto最优解集可供决策者根据经验进一步筛选。采用Python编程语言,联合有限元软件编写基于该方法的优化程序,选取主塔、主梁的弯曲应变能之和,主塔成桥后在恒载作用下的纵桥向位移平方和作为目标函数,以施工过程及成桥后结构处于安全状态和索力总体分布均匀作为约束条件。工程算例优化结果表明,该方法能够快速搜寻到Pareto最优解集,并从中筛选出最优解,其结构应力处于安全范围,主塔线形合理,索力总体分布均匀。该方法可应用于斜拉桥成桥和施工阶段索力的确定及梁拱组合体系桥梁吊杆索力的确定。     

Collision performance of bitubular tubes with diaphragms

A numerical study of bitubular tubes with diaphragms compared with single and bitubular tubes subjected to dynamic axial impact force was presented. At first, the energy absorption response of the composite structure under axial loading was analyzed by finite element simulation. The results show that the efficiency of energy absorption can be improved by introducing diaphragms to the double-walled columns. Then, the effect of the amount and location of diaphragms, the shape and the size of the inner tubes, and the thickness of the composite structures were also studied numerically. The collision performance of the composite structure is affected by the deformation of diaphragms, as well as the interaction of outer and inner tube. The non-uniform distribution of diaphragms can improve the energy absorption efficiency of structures for a constant number of diaphragms. The specific energy absorption of the hexagonal inner tube is the highest, followed by the circular, octagonal and square ones.     

高能效高速稳态铣削参数优化

为了提高铣削加工的能量利用率,提出了一种以无颤振切削为约束条件,以能量利用率为优化目标的铣削参数优化方法.基于机床的能耗特性,建立了提高能量利用率的无颤振铣削参数优化模型.利用切削稳定域图确定主轴转速的优化区间,利用切削力、切削功率、切削速度等条件确定切削深度、切削宽度及进给速度的优化区间,并通过合理选择各参数的优化步长快速获得切削参数.以五轴雕铣机为实验机床,45#钢为切削材料进行了验证试验,结果表明,该参数优化方法使能量利用率得到了较大提高.     

Dynamic rupture and crushing of an extruded tube using artificial neural network(ANN) approximation method

A numerical study of the crushing of thin-walled circular aluminum tubes has been carried out to investigate the crashworthiness behaviors under axial impact loading. These kinds of tubes are usually used in automobile and train structures to absorb the impact energy. Previous researches show that thin-walled circular tube has the highest energy absorption under axial impact amongst different structures. In this work, the crushing between two rigid flat plates and the tube rupture by 4 and 6 blades cutting tools is modeled with the help of ductile failure criterion using the numerical method. The tube material is aluminum EN AW-7108 T6 and its length and diameter are 300 mm and 50 mm, respectively. Using the artificial neural network(ANN), the most important surfaces of energy absorption parameters, including the maximum displacement of the striker, the maximum axial force, the specific energy absorption and the crushing force efficiency in terms of impact velocity and tube thickness are obtained and compared to each other. The analyses show that the tube rupture by the 6 blades cutting tool has more energy absorption in comparison with others. Furthermore, the results demonstrate that tube cutting with the help of multi-blades cutting tools is more stable, controllable and predictable than tube folding.     

Crushing analysis and multiobjective crashworthiness optimization of bitubular polygonal tubes with internal walls

In order to reduce casualties and property losses in a collision accident, thin-walled structure has been extensively used as energy absorber in crashworthiness design of train. With the help of energy absorber, collision kinetic energy can be controllably dissipated by the plastic deformation of structures. A new kind of multi-cell thin-walled structure called as bitubular polygonal tubes with internal walls(BPTIW) was constructed. The crashworthiness characteristics of BPTIWs were investigated by LS-DYNA. It can be found that the BPTIW with 12 sides has the most excellent crashworthiness characteristics. Therefore, based on response surface method(RSM) and multiobjective particle optimization(MOPSO) algorithm, the BPTIW with 12 sides was selected to optimize the dimensions of cross-sectional configuration under different constraints of energy absorption(EA) and crushing peak force(CPF). The results show that the optimal designs of BPTIW12 under different constraints present excellent crashworthiness characteristics and can be used in the practical engineering.