改进的遗传算法求解桁架的形状优化

提出将改进的遗传算法用于优化具有离散尺寸、连续形状变量的桁架重量. 考虑到离散和连续变量的本质，提出了混合编码方法，其中包括二进制和实数编码，整 数和实数编码. 采用了凝聚选择法------基于约束和适应度值双重标准，完全适应约束问题 的本质. 竞争保留最优个体方法延长了优良个体的寿命，使好基因有更大的机会遗传给 下一代. 算例表明改进的遗传算法是可行且有效的.

IMPROVED GENETIC ALGORITHM FOR SHAPE OPTIMIZATION OF TRUSS STRUCTURES

This paper presents an improved genetic algorithm (GA) to minimize the weight of a truss with discrete sizing,continuous shape variables.Because of the nature of discrete and continuous variables,mixed coding schemes are proposed,including binary and float coding,integer and float coding.Surrogate reproduction is developed to select good individuals to mating pool on the basis of constraint and fitness values,taking full account of the character of the constrained optimization.This paper proposes a new strategy of creating next population by competing between parent and offspring populations based on constraint and fitness values;so that the lifetime of the excellent gene is prolonged.Standard examples are solved,numerical solutions are shown to be better than those in the literature.