ESO在2-D结构模型优化中的改进及应用

IMPROVEMENT OF EVOLUTIONARY STRUCTURAL OPTIMIZATION METHOD FOR 2-D MODEL

针对ESO在2-D结构模型优化中出现的畸变单元以及优化结果可能落入局部最优问题,提出2种算法。其一,基于畸变单元特征的筛选和删除算法。畸变单元的修正只需通过一个参数控制,该参数由其周围单元的联接个数决定;其二,通过区间逼近算法确定满足单元删除判定条件所对应的最小初始删除率R_(0min),以该删除率作为起始值,通过设定一定大小的增量确定多个初始删除率R_0。将以上算法植入到原有ESO优化步骤中,分别以得到的不同初始删除率开始优化,根据性能参数从优化得到的多个拓扑结构中筛选出可用结构。对多个2-D结构拓扑优化表明,改进的ESO方法在工程适应性和稳定性上优于现有ESO方法,且避免了单一结果落入局部最优解的不足。

which the singular element appears in the optimum process and the result may be a partial optimum solution are two disadvantages when using the ESO method to optimize 2 - D model. In this paper, two algorithms are proposed for solving these disadvantages. One is filter and rejection algorithm based on the trait of singular element. Using this algorithm, only one parameter is needed to control filtering and deleting, and the parameter is determined by the number of elements linked around singular element. The other is interval approximation algorithm. Minimum initial rejection rate R0min which fulfill removed conditions was ascertained by using this algorithm and it was used as starting value, thus other initial rejection rate R0 were obtained by setting certain increment. Two algorithms mentioned above were implanted in the existing ESO method, then optimizing respectively with different initial rejection rate which were obtained before and the available structures from the results was filtered out in terms of performance parameters. The results of optimization for numerical 2-D structures indicate that the improved ESO method has better suitability and stability than the existing one, and it avoids shortcoming that the resuh may be a partial optimum solution when using the existing ESO method.