DDDU(W)结构优化微机程序系统对客车车身结构的优化设计

利用大连理工大学工程力学研究所研制的结构优化设计程序DDDU(w)对AK6980HK车身骨架结构进行了优化设计。     

渐进结构优化法(ESO)和双向渐进结构优化法(BESO)的近期发展

本文介绍渐进结构优化法和双向渐进结构优化法的近期发展和主要研究成果.从理论层面对该方法的合理性、连续体拓扑优化在多种工程问题中的应用,以及计算机软件的具体实现, 进行了阐述及算例演示.这些结果充分展示了渐进结构优化法解决实际工程优化设计问题的能力,以及其通过现有成熟建模界面广泛应用于日常建筑和机械结构设计的可行性.      

等几何壳体分析与形状优化

首先基于Reissner-Mindlin理论进行了三维壳体等几何分析,而后基于此对三维壳体进行形状优化,提出了形状优化中灵敏度的全解析计算方法,包括位移应变阵、雅克比阵和刚度阵等相对控制顶点位置的灵敏度解析计算公式;通过实例验证了壳体等几何分析和灵敏度全解析计算方法的有效性。与传统的基于网格的灵敏度半解析计算方法相比,基于NURBS的灵敏度全解析计算具有精确、计算效率高的特点,且可以避免优化迭代中的网格畸变。     

等几何壳体分析与形状优化

首先基于Reissner-Mindlin理论进行了三维壳体等几何分析,而后基于此对三维壳体进行形状优化,提出了形状优化中灵敏度的全解析计算方法,包括位移应变阵、雅克比阵和刚度阵等相对控制顶点位置的灵敏度解析计算公式;通过实例验证了壳体等几何分析和灵敏度全解析计算方法的有效性。与传统的基于网格的灵敏度半解析计算方法相比,基于NURBS的灵敏度全解析计算具有精确、计算效率高的特点,且可以避免优化迭代中的网格畸变。     

结构优化设计的KFD方法及其在电除尘器本体结构优化中的应用

电除尘器本体结构优化设计是一个规模大,设计变量数多而具有相当难度的几何可调和拓扑可调优化设计问题。对这样一个大型复杂的结构优化问题,本文在文[1]的工作基础上,充分利用结构的力学特性,应用有效设计变量的概念,建立了不用求偏导数且不必解线性规划的可行方向法—KFD方法。该方法具有收敛速度快、占用内存少的优点,比通常ε有效约束可行方向法提高速度数十倍。实际应用的结果表明文中的方法是很有效的。     

复合材料翼面结构优化设计及分析

复合材料具有比强度高、比刚度大、抗疲劳等诸多优异性能,在航空航天结构中得到了广泛的应用.复合材料在新研制的飞机上的应用比重也越来越高,在大型民用飞机Boeing787上,复合材料结构重量占到了全机结构重量的50%.复合材料层合板具有无与伦比的设计潜力,成为复合材料中使用最多的一种结构形式.本文以某型号飞机机翼翼盒为研究...     

互逆规划理论及其用于建立结构拓扑优化的合理模型

在数学规划的领域里定义了互逆规划——各自目标函数与约束条件位置相互交换的一对规划. 接着指出,尽管互逆规划与对 偶规划在表面上似乎类似,但是二者存在 5 点不同:(1) 是否为同一个问题的不同;(2) 存在``对偶间隙'与否的不同;(3) 设计变量数目的不同;(4) 是否单目标与多目标问题的不同;(5) 问题合理与否的不同. 然后,基于互逆规划的定义,用以审视结 构拓扑优化模型,给出如下结果:(1) 从这个角度洞悉,在结构优化中,确实有不合理的模型一直被沿用着;(2) 找到了修正不 合理模型使之合理化的方法;(3) 对于给定体积下的柔顺度最小化 (MCVC) 模型,指出了其不合理的原因;(4) MCVC 模型实际是互 逆规划的 m 方,由此建立起其对应的 s 方, 即给出了多个柔顺度约束的体积最小化 (MVCC) 模型;(5)给出了MVCC模型中的结构 柔顺度约束的物理解释和算法,论证了 ICM (independent continuous and mapping) 方法以往关于全局化应力约束的概念和方法;(6)数值算例表明了 MCVC 与 MVCC 模型作为互逆规划的差异,且印证了 MVCC 模型的合理性.MCVC 模型在不同体积约束及多工况下不同的权系数时,得到最优拓扑不同;但 MVCC 模型在多工况柔顺度约束下可得到唯一的最优拓扑.      

曲厚壳单元在斜板拱桥分析中的应用

介绍了利用曲厚壳单元对斜板拱桥进行空间受力分析,并将曲厚壳单元所得结果与采用实体单元分析的结果和模型实验所得结果进行了比较,证明利用曲厚壳单元来分析斜板拱桥是行之有效的。     

考虑结构损耗时水中圆柱壳的振动声辐射特性研究

基于圆柱壳的振动方程以及壳与流体边界上振速连续条件,推导了简支在刚性圆管上的有限长圆柱壳的低频声辐射的自辐射阻抗和互辐射阻抗计算公式,在考虑结构损耗情况下求解了圆柱壳的机械阻抗、表面振速、辐射声功率、辐射效率以及辐射声场的分布特征。结果表明:低阶模态自辐射阻抗大于互辐射阻抗,且自辐射阻随模态阶次增大迅速减小;当p、m同为偶数或奇数时模态辐射阻系数rpmqq大于零,反之小于零。模态辐射抗系数xpmqq在零值附近波动并当ka趋于无穷大时xpmqq都趋向零;p与m相差越大,rpmqq和xpmqq越小。当激励力频率较低时圆柱壳辐射声场指向性为"∞"和"8"叠加的形状;随频率增高,轴向模态和周向模态综合效果导致辐射声场指向性趋于复杂。计算简支圆柱壳的声辐射特征,必须要考虑结构的损耗。     

Natural Vibrations of a Cylindrical Shell with Circular Ribs Attached by Means of Discrete Elastic Elements

The vibrations of a cylindrical shell reinforced with circular ribs attached to it by means of discrete elastic elements are studied. The problem is solved by the finite-element method. The shell and ribs are modeled by a plane four-node finite element, which is a combination of a four-node plane stress element and a four-node flexural element. The effect of the stiffness of the elastic elements on the natural frequencies and modes is examined __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 10, pp. 108–113, October 2005.     

Propagation of Harmonic Waves in a Cylindrical Shell (Timoshenko Model)

Equations for studying the axisymmetric deformation of a cylindrical shell are derived on the basis of Timoshenko shell theory. A dispersion equation is set up to study natural harmonic waves in a cylindrical isotropic shell. A numerical approach to plotting dispersion diagrams is proposed. The wave velocities obtained coincide with analytical solutions     

Natural Vibrations of a Cylindrical Shell Reinforced with Two-Layer Rings

The vibrations of a cylindrical shell reinforced with ring ribs attached to the shell by means of elastic elements are studied. The problem is solved by the finite-element method. The shell and ribs are modelled by a plane four-node finite element, which is a combination of a four-node plane stress element and a four-node flexural element. The effect of the stiffness of the elastic elements on the natural frequencies and modes is examined __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 8, pp. 105–110, August 2005.     

Mass optimization of a compressed cylindrical shell with limited life

A new optimization model is proposed to design corrosion-affected structures with limited life. The optimization problem is stated as a nonlinear-programming problem. The mass of the structure is minimized. The design is considered optimal when physical wear and obsolescence arrive simultaneously. A smooth cylindrical shell compressed in the longitudinal direction is used to illustrate the model __________ Translated from Prikladnaya Mekhanika, Vol. 42, No. 3, pp. 97–101, March 2006.     

Dispersion Equations for Harmonic Waves Propagating along a Cylindrical Shell Reinforced with A Rib Mesh (Single-Mode Approximation)

The dispersion equations for harmonic waves propagating along a cylindrical shell reinforced with a rib mesh are derived in single-mode approximation. The influence of the geometrical parameters of ring frames on the cutoff frequencies is studied by numerical examples. It is shown that with increase in the stiffness and number of frames, the number of dispersion curves decreases and their shape changes     

Features of the Motion of a Gas-Liquid Medium in a Compound Shell (Sphere and Truncated Cone) Subject to Vibration

The results from an experimental study into the dynamic behavior of a gas-liquid medium and solid particles in a compound shell (sphere-truncated cone) are reported on. The following processes are studied: formation of gas bubbles and their clusters, strong macroflows, and intensive chaotic motion of the medium in the truncated cone as a nonlinear vibrating liquid-gas system__________Translated from Prikladnaya Mekhanika, Vol. 41, No. 1, pp. 112–118, January 2005.