典型复合材料加筋壁板优化设计

针对复合材料加筋壁板的稳定性优化问题提出了一种用混合罚函数法、Powell法、黄金分割法、改进的坐标轮换法和遗传算法相结合的混合优化算法.并通过优化程序实现了以加筋板的屈曲载荷最大为目标的优化设计,最后通过算例验证了优化方法的有效性,同时对优化结果进行了深入地分析.得到的结论对加筋板的设计有一定的指导意义.     

曲加筋条壁板优化设计研究

针对多设计变量的新型曲加筋条壁板(curvilinearly stiffened panels)优化问题,提出了一种参数化设计方法。该方法以加筋壁板的重量最小为目标,以加筋壁板屈曲、von Mises应力和筋条压损等为约束条件,通过MSC.Patran/Nastran进行参数化建模并获得结构响应,采用非劣分层遗传算法Ⅱ(NSGA-Ⅱ)实施结构优化。为了合理、简洁地描述曲加筋条的几何形状,采用B样条定义曲加筋条的轴线,并取其起点、终点和控制点坐标为位置/形状设计变量。利用单级优化策略,同时对位置/形状变量和包括筋条高度、筋条厚度以及平板厚度在内的尺寸变量进行优化。采用该设计方法,在结构承受面内压缩和剪切载荷以及四边简支的条件下,分别对采用直/曲加筋条的壁板进行了轻量化设计。结果表明,复杂载荷作用下,采用相同数目的曲加筋条能够提高结构效率,实现结构减重。     

整体加筋壁板轴压承载能力计算方法研究

准确计算整体加筋壁板轴压承载能力是机翼壁板设计分析中的关键因素,对飞机机翼结构效率的提高和重量控制至关重要。因此必须研究掌握更为精确的整体加筋壁板轴压承载能力计算方法。在提出加筋壁板弯曲承载能力等效法的基础上,结合壁板轴压试验研究了三种蒙皮有效宽度计算方法的准确度,同时比较喷丸与未喷丸的壁板单元压损试验结果,引入了喷丸处理对整体加筋壁板压缩强度的影响量,从而建立了更加完善准确、实用的工程计算方法。     

典型加筋壁板纯剪切工况有限元模拟

针对典型加筋壁板纯剪切试验夹具,利用Abaqus软件对该纯剪切工况进行模拟,验证夹具设计的合理性。采用一维、二维和三维单元相结合的方式,显著提高计算效率。从壁板承受面内剪力角度分析加筋壁板的整体受力情况。计算结果表明,整体模型von Mises应力呈现中心对称性,壁板芯边界上距加载端较远区域应力分布均匀,满足纯剪切条件;壁板向加筋条的载荷传递效率较低;夹头螺栓附近应力呈现较好的对称分布。     

星载电子设备加筋板优化设计

星载电子设备动力学性能对于卫星工作可靠性具有重要意义。本文以某卫星星载电子设备为研究对象,采用拓扑优化与尺寸优化相结合的方法研究了该电子设备机箱加筋板的结构设计。建立了两层实体单元的板结构,以一阶频率最大为目标,通过拓扑优化得到加强筋结构的拓扑分布;之后在拓扑构型基础上,以结构质量最小为目标,一阶频率作为约束条件进行尺寸优化得到加筋板的详细结构。     

加筋板结构静态性能分析及优化设计

对于工程中广泛使用的加筋板结构,利用有限元分析的方法,对井字型、X型和蜂窝型三种典型加筋板类型进行了静刚度性能分析及比较,并研究了结构参数对加筋板性能的影响,且根据分析结果总结了加筋板类型和结构参数的优化方向.     

基于有限元分析的平盖加筋封头结构优化设计

将有限元方法与优化技术相结合,利用APDL语言建立了参数化模型,完成了某平盖加筋封头的结构优化设计,并将最终优化得到的结构尺寸与原始设计尺寸通过应力分析进行比较。结果显示这种方法可以用于工程实际,对平盖的结构改进设计具有一定指导作用。     

基于响应面法的薄壁机匣加筋肋优化设计

加筋肋是提高薄壁机匣刚度普遍采用的结构形式,合理的加筋肋形式及位置可以起到抑制薄壁机匣振动的效果。采用有限元法对某型航空发动机加筋肋薄壁机匣模型振动特性进行分析计算,并利用锤击法对其进行模态试验,通过结果分析验证了计算结果的准确性。研究加筋肋位置和截面几何参数变化对机匣固有频率的影响;采用响应面法对加筋肋位置进行优化设计,通过有限元验证优化结果的准确性。分析表明在保证质量不变的情况下,加肋结构减振效果明显。     

整体壁板结构纵向连接接头的优化设计

纵向连接接头是影响机身整体壁板结构的安全疲劳寿命的关键部位,文中对三台阶搭接型、简单搭接型和两台阶搭接型三种机身整体壁板的纵向连接形式进行研究,应用Ansys软件建立这三种连接形式的铆钉接头结构件的参数化全局三维壳体有限元模型及局部细节子模型,进行静强度求解分析,确定接头结构件的铆钉孔边的应力集中系数,并对接头结构件的部分几何构形参数进行敏感性分析和优化设计,为纵向连接接头结构件的抗疲劳设计及综合验证提供科学依据.     

复合材料加筋壁板稳定性影响分析

分别运用特征值法和弧长法开展T字型加筋壁板稳定性及其影响因素分析.分析表明:特征值法和弧长法所得结果相近,弧长法分析结果较为安全,特征值法可作为观察模型屈曲位置及模态图的分析方法.加筋壁板屈曲载荷随筋条间距的变化呈抛物线状,较平均的筋条布置有利于加筋壁板的整体稳定性.加筋壁板屈曲载荷随凸缘宽度的变化呈抛物线状,保持筋条横截面面积不变,筋条凸缘宽为60mm时屈曲载荷达到最大值.较小的凸缘宽度会导致筋条屈曲的发生,应在实际设计中予以避免.     

Critical buckling of stiffened panels with discrete point connections

Point connections representing spot welds, bolts, rivets, screws, pins, etc. have been included in the powerful panel analysis and design computer program VICONOPT. The exact stiffness matrices of component structures are coupled by using Lagrangian multipliers to represent these point connections between the structures. The new approach gives a very quick and accurate analysis when longitudinal lines of point connections are used in panels which are loaded only in compression. In this case only one point connection needs to be modelled and only certain response wavelengths contributing to the buckling mode are used. Accurate solutions are also obtained for shear loaded panels but at a much greater computational cost. Illustrative examples include comparisons between results for line and point connections, indicating to designers how many point connections are required to produce an effective line connection. These comparisons cover both pure axial compression and pure shear loading cases for both isotropic and anisotropic panels. They suggest that for many panels, manufacturing costs could be reduced by using fewer point connections, with minimal reduction in the stability of the panel. The work presented here is of particular importance to aircraft panels where point connections are extensively used to connect component structures together.     

聚氨酯板连续生产线软件控制平台设计实现

结合工程实际进行研究,针对聚氨酯板断续式生产模式生产效率低的问题,开发了一套软件控制平台,实现了连续生产线的自动化控制.系统可实现对生产订单的管理、订单数据到生产数据的转换,对生产报表的统计和管理.该系统的成功应用,大大减少了操作人员的工作量,提高了生产效率和产品质量.     

基于ANSYS的贴片机床身结构优化设计

提高贴片机床身的低阶频率是提高贴片机结构精度、避免共振、降低振幅的有效措施,为了提高其低阶频率,针对影响床身动态性能的3个主要因素,运用有限元分析软件ANSYS,对贴片机床身及其改进结构进行了模态分析,得到了贴片机床身结构的优化模型.分析结果表明,通过改变筋板布置方式、改变板厚和单元格开窗尺寸可对床身进行优化,优化后的结构低阶频率有了明显提高.     

Dynamic instability analysis of stiffened shell panels subjected to partial edge loading along the edges

The dynamic instability characteristics of stiffened shell panels subjected to partial in-plane harmonic edge loading are investigated in this paper. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. As the usual formulation of degenerated beam element is found to overestimate the torsional rigidity, an attempt has been made to reformulate it in an efficient manner. Moreover, the new formulation for the beam element requires five degrees of freedom per node as that of shell element. The method of Hill's infinite determinant is applied to analyze the dynamic instability regions. Numerical results are presented through convergence and comparison with the published results from the literature. The effects of parameters like loading type and shell geometry are considered in the dynamic instability analysis of stiffened panels subjected to non-uniform in-plane harmonic loads along the boundaries. The tension buckling aspect of the stiffened panels are also considered and the dynamic stability behavior due to tensile in-plane edge loading is studied for the concentrated load.     

Numerical analysis of static performance comparison of friction stir welded versus riveted 2024-T3 aluminum alloy stiffened panels

Most researches on the static performance of stiffened panel joined by friction stir welding（FSW） mainly focus on the compression stability rather than shear stability. To evaluate the potential of FSW as a replacement for traditional rivet fastening for stiffened panel assembly in aviation application, finite element method（FEM） is applied to compare compression and shear stability performances of FSW stiffened panels with stability performances of riveted stiffened panels. FEMs of 2024-T3 aluminum alloy FSW and riveted stiffened panels are developed and nonlinear static analysis method is applied to obtain buckling pattern, buckling load and load carrying capability of each panel model. The accuracy of each FEM of FSW stiffened panel is evaluated by stability experiment of FSW stiffened panel specimens with identical geometry and boundary condition and the accuracy of each FEM of riveted stiffened panel is evaluated by semi-empirical calculation formulas. It is found that FEMs without considering weld-induced initial imperfections notably overestimate the static strengths of FSW stiffened panels. FEM results show that, buckling patterns of both FSW and riveted compression stiffened panels represent local buckling of plate between stiffeners. The initial buckling waves of FSW stiffened panel emerge uniformly in each plate between stiffeners while those of riveted panel mainly emerge in the mid-plate. Buckling patterns of both FSW and riveted shear stiffened panels represent local buckling of plate close to the loading corner. FEM results indicate that, shear buckling of FSW stiffened panel is less sensitive to the initial imperfections than compression buckling. Load carrying capability of FSW stiffened panel is less sensitive to the initial imperfections than initial buckling. It can be concluded that buckling loads of FSW panels are a bit lower than those of riveted panels whereas carrying capabilities of FSW panels are almost equivalent to those of riveted panels with identical geometries. Finite elem     

带式输送机头部支架的结构优化设计研究

采用有限元法,建立了带式输送机头部支架的有限元力学模型,利用10节点四面体单元进行网格划分,并进行了受力分析,完成了头部支架有限元结构分析。利用ANSYS软件的APDL参数化语言,建立了头部支架的结构优化设计数学模型,创建了优化控制文件程序(ODPST),完成了头部支架的结构优化设计,取得了合理和满意的设计结果。     

Optimal design of stiffened laminated plates using a homotopy method

The use of a homotopy method is demonstrated for optimal design of a stiffened laminated plate for maximum buckling load. Instead of obtaining a single optimum, the homotopy technique generates in a single computer execution an entire family of optimum designs with a given parameter. In the present application the parameter is set to the total structural weight, and the optimal designs are obtained as a function of the weight of the laminated plates. It is seen that the number of simultaneous buckling modes of optimum plates is increased as the total weight is increased. So for low weights the optimal design starts with unimodal design and for higher weight the optimal design becomes bimodal, trimodal, and finally it becomes tetramodal.     

车身覆盖件冲压工艺多目标优化系统的集成与应用

采用有限元分析技术和优化技术,以实现车身覆盖件的冲压工艺多目标优化。定义了材料、工艺和几何3类主要设计变量,其交集为最佳设计变量空间。针对覆盖件的整体成形性,建立破裂、起皱和变形不足3类目标函数,采用增量有限元和全量有限元的整合策略,求解目标函数值。与其他算法相比,基于帕累托法的多目标遗传算法能求解最佳解空间的所有解,完全满足不同成形性之间的权衡需要。最后,以车身发动机罩外板为例,验证了该优化系统的应用。     

ANSYS参数化有限元技术在板壳结构拓扑优化设计中的应用

拓扑优化设计是工程结构降低成本、提高性能的有效手段之一.在ANSYS对加筋板壳结构的有限元分析基础上,可以对板壳结构的加强部件分布进行合理设计.着重介绍了使用ANSYS参数化语言进行加筋板壳结构的分析方法.     

带锯机架整体的筋板结构设计与优化

为减小木工带锯机床整体振动,提高加工精度,降低整体质量,对筋板结构建立系统振动数学模型,根据运动微分方程对筋板结构单元进行动态性能和载荷分析,得出最适合该机床的筋板结构类型,并采用三维建模软件对机床机架进行参数化建模。根据实际工况,采用ANSYS对机架整体进行有限元静力学分析。基于静力学仿真结果,采用拓扑优化方法对机架进行轻量化设计,并对机架尺寸提出修改和优化方案。研究结果表明,井字形筋板结构和T字形筋板结构为该机架的最优筋板结构单元,且满足刚度和强度要求;通过轻量化设计使机床整体质量下降16.9%,实现轻量化目标。