复合材料层合板的模糊稳健设计

提出对复合材料结构进行稳健可靠性设计,设计中同时考虑了随机因素和模糊因素的影响.首先考虑约束的模糊性,建立了复合材料层合板的模糊优化设计模型.在模糊优化设计的基础上,考虑纤维角度和单层板厚度的变异对模糊约束的影响,进一步研究了复合材料层合板的模糊稳健设计.算例说明了本文提出的方法的有效性,对复合材料结构的合理设计具有一定的指导意义.     

Multiparameter Optimal Design of Plates and Shells

For global behavioral constraints, the problem of optimal design of plates and shells is formulated by assuming the design to be dependent upon a set of design parameters. Global minimum theorems are proved for some constraints, whereas for others only local extremum conditions are derived. A possibility of constructing some numerical algorithms by using the optima-lity condition and proper variational principle is discussed. The following behavioral constraints are considered: prescribed mean compliance measurer1 as the work of surface tractions, prescribed local deflection of linearly or nonlincarly elastic structure, given set of several free frequencies, prescribed safety factor for limit load of a plastic structure, any global constraint ex pressed as a surface integral with integrand depending on generalized stresses or strains.     

基于多目标优化策略的结构可靠性稳健设计

应用可靠性稳健优化设计理论和多目标决策方法,将结构可靠性稳健优化设计转化为多目标优化问题。运用灰色理论中的关联分析法,选取粒子群算法中的全局极值和个体极值,提出了灰色粒子群算法求解可靠性稳健优化设计问题。与传统方法相比,该方法简便易行并能迅速准确地得到结构可靠性稳健优化设计信息。     

ROBUST OPTIMUM DESIGN OF LAMINATED COMPOSITE PLATES

A last-ply failure (LPF) analysis method for laminated composite plates is incorpo- rated into the ?nite element code-ANSYS, and a robust optimum design method is presented. The composite structure is analyzed by considering both in-plane and out-…     

Optimal Shape Design of Multicomposite Structures

Abstract

The problem of the optimal shape design of an elastic composite structure with unspecified interfaces is discussed for the case of mean compliance constraint. The optimality conditions are derived, and the optimization of a circular plate with segmentwise constant thickness is considered in order to illustrate these conditions. The case of optimal plastic design is obtained as a limiting case of mean compliance design.     

基于神经网络的机械零部件可靠性稳健设计

将可靠性优化设计理论、可靠性灵敏度技术和可靠性稳健设计方法相结合,利用神经网络的非线性映射功能,模拟得到随机设计变量与机械零部件结构响应之间的关系,以训练好的神经网络模型为基础,结合随机摄动技术,进行结构可靠性稳健设计.从而解决了工程实际中很难给出极限状态函数的显性表达式问题,并有效地克服了目前随机有限元法和响应面法存在的缺陷.     

非匀质材料板的微结构优化设计

探讨具有微结构构造的非匀质材料构件在微结构层次上的优化设计,即寻求满足构件宏观性能要求的最佳微结构材料与构造参数。文中采用细观元法确定非匀质材料构件宏观性能与材料微结构参数间定量关系,建立起微结构优化设计数学模型,具体分析了复合材料板件满足强度、刚度要求的最佳微结构参数。有关方法可适用于复合材料、功能梯度材料、智能材料等新材料构件。     

冷弯薄壁槽形截面钢柱的优化设计

求解冷弯开口薄壁截面短柱的极限承载力是一个板组结构的大挠度弹塑性分析问题，板件之间相互作用和纵向面内加载方式对其局部屈曲后性能和稳定极限承载力有很大的影响。本文应用大挠度弹塑性有限条分析方法系统地研究了冷弯薄壁槽形截面柱的极限承载能力和它们的优化性能，并对荷载偏心距为常数和位移梯度为常数的两种加载条件下的薄壁开口短柱局部屈曲后性能和极限承载力进行了对比分析和探讨。     

Sensitivity Analysis and Optimal Design of Nonlinear Beams and Plates

A uniform formulation of sensitivity analysis for beams and plates is presented in terms of generalized stresses and strains. Both physical and geometric nonlinearities can be treated within this formulation. Next, optimal design problems for stress and deflection constraints are formulated and the relevant optimality conditions are derived using the concept of a linear adjoint structure. Finally, several numerical solutions of optimal design problems of beams are presented.     

Optimal Design of Rotating Disks in Creep

Abstract

Minimum-weight design of axially-symmetric rotating disks in a state of stationary creep is determined for a prescribed value of the creep velocity at the outer edge of the disk. The constitutive equations used for stationary creep are Norton's law generalized to multiaxial states of stress based on von Mises' criterion and associated flow rule. The resulting nonlinear optimization problem is solved iteratively using a series expansion to approximate the thickness variation of the disk, In each iteration step the nonlinear creep equations are solved for the stresses and a linearized perturbation problem is solved for the stress gradients. The optimization procedure is used to determine the optimal shape of a solid rotating disk carrying a uniform traction at the outer edge, and this result is compared with the corresponding disk of uniform strength. Variations in the optimal shape due to a central hole and due to temperature distributions are illustrated by some examples.     

复合材料加筋壁板的优化设计

本文用简化的方法,考虑了受压及压剪联合作用的复合材料加筋壁板的总体屈曲和局部屈曲、材料强度、刚度、轴向应变等因素以及其它工程要求的影响,用数学规划法提出壁板的优化设计问题,用乘子罚函数法求解。以石墨-环氧帽型加筋板为例,所得优化设计结果与NASA得出的最优曲线一致,证明了所用方法的可靠性,并可进一步推广应用于工程实践。     

捷联惯导系统圆锥补偿算法优化设计

高速、高速度的圆锥偿补算法是提高捷联惯性导航系统（ＳＩＮＳ）性能的重要环节。本文对Ｃｈａｎ Ｇｏｏｋ Ｐａｒｋ等提出的新圆锥补偿方法进行了进一步的研究。文中给出了经典圆锥运动的角速度模型,推导出了经典圆锥运动的角增量公式、角增量叉乘公式、圆锥补偿系数方程和误差公式,并将该方法拓展至利用前一圆锥补偿周期角增量和的圆锥补偿算法。     

Optimal Elastic Design for Prescribed Maximum Deflection

ABSTRACT

For the problems of the optimal elastic design with prescribed maximum deflection, a variational formulation is proposed, with reference to the one-or two-dimensional bending structures.

Necessary optimum conditions are found, and the physical features of the optimal solutions are discussed for the “absolute” minimum cost problems, and, when dealing with beams, for the solutions with piece-wise constant design function.

Some examples are solved by using numerical methods that are directly derived from the variational formulation.     

Optimal Design and Reliability Evaluation of Multi-State Series-Parallel Power Systems

A new approach is introduced for calculating the electrical power system reliability indices. Such as multi-state stationary availability, the expected multi-state capacity, the expected unsupplied demand, the loss of load probability and total failed system probability. A multi-state system consisting of elements combined into a series-parallel structure is considered. When the system consists of elements with different reliability and performance (productivity or capacity) characteristics, its availability, defined as the ability to meet a demand, strongly depends on the selection of components and the system structure design. In this paper we present an ant colony method which treats the more sophisticated and realistic models in which components and systems may assume many states ranging from perfect working to complete failure. The objective is to calculate the different reliability indices by using the new modern technique of Ushakov (UMGF technique). A computer program has been developed to implement the UMGF technique. An illustrative example is presented.     

Workspace and Optimal Design of a Pure Translation Parallel Manipulator

This paper presents a study of a pure translation three degrees of freedom fully-parallel manipulator, known as the Tsai manipulator. Based on the static analysis and on the determination of the singularity loci of the manipulator, criteria for the optimal geometric design of the manipulator for a given workspace free from singularities are proposed.     

Constrained Optimal Design of Columns Against Buckling∗

The buckling loads of straight, simply supported columns, loaded by axial thrust are maximized, subject to the restriction that the available volume of structural material is specified. In addition, a constraint is placed upon the maximum allowable prebuckling stress. Analytic solutions are presented for a variety of different cross-sectional geometries.     

Optimal Design of Shells Subjected to Impulsive Loading

The paper is concerned with the mass optimization of a smooth cylindrical shell subjected to short-term aperiodic loads in the form of axial compression pulses. The optimization method chosen is random search with controlled limits of optimized parameters. The effect of the pulse duration and the load level on the optimal design is analyzed. The results obtained by two methods are compared __________ Translated from Prikladnaya Mekhanika, Vol. 41, No. 8, pp. 97–104, August 2005.     

Duality among Optimal Design Problems for Torsional Vibration

ABSTRACT

Four types of mass and frequency optimization problems are stated for free torsional vibration of thin-walled cylinders subject to constraints on wall thickness and frequencies of vibration. It is shown, using Pontryagin's method, that the mathematical structure of all four problems is similar and leads to identical classes of optimal thickness distributions. These duality relations are used in an example to construct an optimal frequency solution from the solutions for both maximum and minimum mass problems. General relations among the governing parameters for the four problems are stated. The results of Grinev and Filippov and of Thermann for the abnormal optimization problems are verfied as a specific limiting example of the general results.     

三维连续体结构形状优化设计

借助于一种名为“函数识别器”的工具,采用“二级控制”法,实现了用设计变量控制网格变动的目的,除此之外,又在单刚对设计变量的导数计算,目标函数的敏度计算方面,提出了新的解决方案,最后给出了两个算例,验证了以上方法是切实可行的。     

多相材料微结构多目标拓扑优化设计

在采用多尺度均匀化方法求解微结构等效特性的基础上，提出了多相材料 微结构的多目标优化设计模型. 以组分材料用量为约束，采用周长控制消除棋盘格，结合有 限元方法和对偶凸规划求解技术，对两相和三相材料微结构多项等效模量的组合进行了优化 设计. 研究比较了微结构网格粗细、材料组分以及三相材料微结构优化中的两相实体材料弹 性模量相对比例不同对优化结果的影响. 数值算例验证了优化模型和优化算法的有效性，表 明了相关因素对优化结果的影响.