共查询到18条相似文献,搜索用时 109 毫秒
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具有动应力和动位移约束的离散变量结构形状优化设计方法 总被引:4,自引:0,他引:4
讨论了动应力、动位移约束下离散变量状优化设计问题。首先用拟静力算法,将结构惯性力极值作为静载荷施加到结构上,求得结构的动位移和动内力,然后将考虑动应力约束和动作移约束的离散变量结构优化设计问题化为静应力和静位移约束的优化问题。在求解过程中,将单元内力作了一阶近似,并将多约束问题转化为单约束问题,然后利用两类变量统一考虑的离散变量结构形状优化设计的综合算法进行求解。 相似文献
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应力和位移约束下的板壳结构截面优化 总被引:5,自引:0,他引:5
将准则法和数学规划法相结合,根据满应力准则将应力约束化为动态下限,借助单位虚载荷法将位移约束转化为设计变量的近似显函数,建立了满足应力和位移约束的优化模型. 为了解决多变量的大型优化问题,根据对偶理论将上千设计变量的优化模型转化为几个变量的对偶模型,并通过二次规划求解. 以MSC/Nastran软件为结构分析的求解器,借助MSC/Patran软件为开发平台,完成了板壳结构截面优化程序. 程序完全和Patran及Nastran融为一体,在Patran中建立模型,利用Nastran分析计算,根据优化结果对设计变量调整,再用Nastran进行结构重分析,反复迭代直到结构重量收敛. 算例表明程序的合理性和有效性,能够满足工程设计的需要. 相似文献
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本文提出了一种新的桁架结构拓扑优化设计方法,在该方法中,以杆件内力为设计变量,以由结构力学的基本方程构成的位移、应力等物理量为约束,构成了拓扑优化的线性规划模型。它克服了目前桁架结构拓扑优化的两大困难——预定设计位移场与在拓扑优化过程中无法考虑位移、应力等性态约束。文章最后给出了两个考题,说明了本方法的可行性与有效性。 相似文献
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Topology optimization of truss structures with systematic reliability constraints under multiple loading cases 总被引:6,自引:0,他引:6
In this paper, a mathematical model for topology optimization of truss structures with constraints of displacement and system
reliability under multiple loading cases is constructed. In order to avoid the difficulty of computing the structure's system
reliability, a solving approach is presented in which the failure probability of system is divided into the sum of all bars'
failure probability by means of reliability distribution. In addition, by drawing into the reliability safety factor and the
fundamental relationship in structural mechanics, all probability constraints of displacement and stress are equivalently
displayed as conventional form and linear function of the design variables. The optimization problem with multiple constraints
is treated by the compact constraint tactics and is solved by the improved simplex method. The examples show that the approach
proposed in this paper is feasible and efficient.
The project supported by the National Natural Science Foundation of China. 相似文献
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桁架结构非概率可靠性拓扑优化 总被引:11,自引:4,他引:7
考虑非概率可靠性的拓扑优化对于非确定参数和荷载条件下结构的概念设计具有重要意义,有关研究国内外少见报道.本文利用凸模型理论,考虑优化迭代过程的需要,提出改进的非概率可靠性指标的定义,并针对桁架结构拓扑优化设计问题建立了以杆件截面积为设计变量、结构重量极小化为目标、具有非概率可靠性指标约束的广义尺寸优化数学模型.本文指出,考虑桁架结构参数的不确定性的条件下所得到的最优杆件布局与确定性优化所得到的结果可能有显著不同.对文中提出的数学模型,采用数学规划算法求解,数值算例结果令人满意.本文工作表明了桁架结构非概率可靠性拓扑优化设计的可行性和所提出算法的有效性. 相似文献
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考虑性态约束时多工况桁架结构拓扑优化设计 总被引:9,自引:0,他引:9
本文提出了一种适用于桁架结构的拓扑优化设计方法。它以杆内力为设计变量,以结构重量为目标函数。该方法的主要特点是:第一,通过引入杆内力为设计变量,既克服了已有方法要求预定位移场这一主要困难,又为在拓扑优化过程中考虑应力、位移等性态约束创造了条件;第二,将多工况的拓扑优化问题描述为一个非光滑的数学规划问题,再通过一个变量代换将其转化为一般的规划为题,进而将原问题的求解又转化为几个线性规划问题的求解;第三,基于结构力学的三个基本方程,将位移与应力约束提成为线性不等式约束,这些约束同重量的目标函数一起构成了拓扑优化设计的线性规划模型。最后,将本方法应用于几个工程算例,得到了满意的数值计算结果。 相似文献
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The present paper studies topology optimization of truss structures in multiple loading cases and with stress constraints.
It is pointed out in the paper that the special difficulty of adding bars and/or deleting bars from structure in the numerical
algorithm of truss topology optimization is caused by the discontinuity of stress functions at the zero cross sectional area
in the conventional formulation. In a new formulation, we replace the stress constraints by new constraints. The new constraints
retain the same feasibility of the stress constraints, but are continuous in the closed interval up to zero cross sectional
area. The new formulation enables us to solve topology optimization problem in the frame of the existing FEM software and
mathematical programming techniques. Powell constrained variable metric method is applied to a number of examples of truss
topology optimization. Numerical performances of the two formulations are compared. It is shown that in the conventional formulation
the iteration of numerical algorithm may be blocked by discontinuity of the stress constraint and often stops at a nonoptimum
solution. And in the new formulation the bar adding and bar deleting is done rationally and a local optimum, even the global
optimum can be obtained by iteration.
The project supported by the National Natural Science Foundation of China 相似文献
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在结构优化中,拓扑优化相比于尺寸优化和形状优化,设计空间更加广泛,因而能够取得更大的效益.近年来,结构拓扑优化逐渐成为人们研究的热点和难点.随着科学技术的发展,工程结构越来越复杂,材料本身和外部环境的不确定性影响加剧,因此在拓扑优化中需要考虑不确定性的影响.本文研究了桁架结构的非概率可靠性拓扑优化问题,用区间模型来量化不确定性,并利用参数顶点组合法来完成不确定性的传播分析,利用基于面积比的非概率可靠性指标构建可靠性拓扑优化模型,提出了功能度量法对原可靠性约束进行等价转化,从而克服了收敛性问题.采用移动渐近方法(MMA)对优化问题进行了求解.数值算例表明,本文提出的功能度量法能够很好地适用于桁架结构的非概率可靠性拓扑优化问题. 相似文献