叠板式多缸薄板成型液压机参数化设计

在已有的300 MN多缸薄板成型液压机的基础上,运用基于VB的SolidWorks二次开发方法与自顶向下完全建模技术,通过驱动模型关键尺寸参数,对新产品进行参数化设计,并用ANSYS仿真优化.通过参数化设计可使该类产品系列化,提高新产品研发速度,促进该类型产品的国产化.     

Solution of the singular discrete regulator problem using eigenvector methods

The discrete regulator problem with a singular state matrix cannot be solved using either the eigenvectors or the sign function of the associated compound matrix, since then, the implicit equation defining the feedback matrix cannot be transformed into the regular discrete Riccati equation. In this paper, it is shown that the solution of a continuous Riccati equation, whose matrix parameters depend on the matrices of both discrete system and cost functional, is the solution of the implicit equation. Since the continuous Riccati equation has symmetric spectrum with respect to the imaginary axis, it has no singularity problem and therefore the matrix sign function method can be used for its solution.     

An expert system for laminated plate design using composite materials

Fibre-reinforced composite materials are introduced as being suitable for aircraft design, and the need for computerizing the design process is explained. Following a brief exposition of the linear theory of composite laminated plates, a prototype expert system for the design of simple load-carrying plates or panels is described. Finally the automatic assessment of the relative merits of designs of different materials using uncertainty reasoning techniques is discussed.     

Reliability-based optimum design of a symmetric laminated plate subject to buckling

This study is concerned with the buckling reliability maximization of a symmetric laminated composite plate with respect to the mean ply orientation angle. The reliability is evaluated by modelling the buckling failure as a series system consisting of potential eigenmodes. The mode reliability is obtained by the first-order reliability theory (FORM), where material constants and orientation angles of individual layers, as well as the applied loads are treated as random variables. In order to keep track of the intended buckling mode during the reliability analysis, the mode tracking method is utilized. Then, the failure probability of the series system is approximated by Ditlevsen's upper bound. The reliability maximization problem is formulated as a nested problem with two levels of optimization. Through numerical calculations, the reliability-based design is demonstrated to be important for the structural safety in comparison with the deterministic buckling load maximization design.     

Unconstrained discrete infmax problem solving applied to yield design

One of the methods of solving unconstrained discrete infmax or minimax problems consists in regularizing the functionF(x)=max _i f _i (x),i=1,...,m, mR ⁿ using various techniques. A new method of solving these problems, which is similar in nature to the regularization method, is presented. It is, however, differentiated from the latter by the fact that regularization is not applied toF(x) but to a function parametered byp (p1), the expression of which does not contain the max operator. Depending on the value ofp, regularization is either local (p=1) or total (p>1).The practical advantage of the proposed method is highlighted in solving large scale problems arising from the static yield design method.     

基于贪婪离散类电磁机制算法求解背包问题

针对基本类电磁机制算法不能够有效解决离散型的背包问题,提出了一种贪婪离散类电磁机制算法。首先,提出一种交叉操作;然后,利用提出的交叉操作对基本类电磁机制算法中的合力计算公式和粒子移动方法进行修改,使其能够适用于离散型问题;最后,引入贪婪算法的机制来处理经过类电磁机制算法迭代得到的解,使这些解满足背包问题的约束条件。通过对3个经典的背包测试问题进行的测试结果表明:该算法可以解决离散型的背包问题,并且具有较优的求解性能。     

A problem reduction based approach to discrete optimization algorithm design

The paper presents a novel approach to formal algorithm design for a typical class of discrete optimization problems. Using a concise set of program calculation rules, our approach reduces a problem into subproblems with less complexity based on function decompositions, constructs the problem reduction graph that describes the recurrence relations between the problem and subproblems, from which a provably correct algorithm can be mechanically derived. Our approach covers a large variety of algorithms and bridges the relationship between conventional methods for designing efficient algorithms (including dynamic programming and greedy) and some effective methods for coping with intractability (including approximation and parameterization).     

复合材料层合板的双Hopf分叉分析

利用高维非线性系统的Hopf分叉定理,研究复合材料层合板的双Hopf分叉.研究了一类受面内激励和横向外激励联合作用下的复合材料层合板在主参数共振—1∶1内共振情况下的双Hopf分叉.首先利用多尺度法得到系统的平均方程,经过简化得到了系统的分叉响应方程.根据对分叉响应方程的分析,得到了系统平衡解的稳定性临界曲线,并给出了系统产生双Hopf分叉的条件.利用数值方法得到系统在参数平面上的分叉集,通过对不同分叉区域的分析,我们发现随着参数的变化复合材料层合板存在不同的周期运动现象.     

压电热弹性体混合层合板的响应分析

根据广义Hamilton变分原理推导出了压电热弹性体非齐次的Hamilton正则方程.考虑热平衡方程与导热方程中变量的对偶关系,通过增加正则方程的维数,成功地将非齐次的正则方程转化为能独立求解的压电热弹性体耦合问题的齐次方程.将非齐次方程转化为齐次方程不仅使问题变得大为简化,同时也减少了数值计算的工作量.数值实例研究了温度载荷和力载荷作用下压电热弹性材料四边简支层合板的响应问题,部分算例与相关文献进行了比较.     

Solution of the stochastic H ∞-optimization problem for discrete time linear systems under parametric uncertainty

The stochastic H _∞-optimization problem for a linear discrete time system with uncertain parameters is formulated and solved. The system operates in the presence of Gaussian random disturbances. The original problem with parametric uncertainty is reduced to the stochastic H _∞-optimization problem without uncertainty and having one extra input, which is essentially the mixed H ₂/H _∞-optimization problem. In a sense, the problem considered in this paper incorporates the classical H ₂/H _∞-and H _∞-optimization problems as limiting cases.     

Transverse shear effect on vibration of laminated plate using higher-order plate element

An approach using a higher-order plate element to include the effect of transverse shear deformation on free vibration of laminated plate is presented. The total displacement of the element is expressed as the sum of the displacement due to bending and that due to shear deformation. The double-sized stiffness and mass matrices due to the separation of bending and shear displacements are then reduced to the size as if only the total deflection was considered. Numerical results for natural frequencies for a range of different isotropic and anisotropic plates with various thickness-to-length ratios are obtained and compared with solutions available in the literature. The effect of transverse shear deformation on natural frequencies of higher modes of laminated plates is also discussed.     

Multi-pulse orbits dynamics of composite laminated piezoelectric rectangular plate

The multi-pulse orbits and chaotic dynamics of a simply supported laminated composite piezoelectric rectangular plate under combined parametric excitation and transverse excitation are studied in detail. It is assumed that different layers are perfectly bonded to each other with piezoelectric actuator patches embedded. The nonlinear equations of motion for the laminated composite piezoelectric rectangular plate are derived from von Karman-type equation and third-order shear deformation plate theory of Reddy...     

Solution of discrete scaled systems via general discrete orthogonal polynomials

General discrete orthogonal polynomials are introduced to analyse and approximate the solution of a class of discrete scaled systems. Using the general discrete shift transformation matrix, together with the general discrete scale matrix, the discrete scaled system can be reduced to a set of simultaneous linear algebraic equations. The coefficient vectors of general discrete orthogonal polynomials can be determined simply by the derived algorithm. Examples are included to show the applicability of the general discrete orthogonal polynomial approximations.     

A discrete optimal control problem

A certain class of discrete optimization problems is investigated using the framework of nonlinear programming. It is shown that a discrete maximum principle similar to the Pontryagin maximum principle is valid for a subclass of these problems, specifically systems with linear dynamics, convex inequality constraints and convex performance criteria. This result extends the applicability of the discrete maximum principle to a class of problems not covered by the Rozonoer-Halkin formulation.