This brief note presents some observations about the modelling of stress constraints in fail-safe structural optimization considering local degradation of member properties. An analytical study of a three-bar example demonstrates the impact of the constraint modelling choices on the optimal design. One notable finding is that degradation of one arbitrary member may cause a worse objective function than complete removal of the member. The observation is similar to the singular optimum issue in topology optimization with stress constraints, but applies also to sizing problems. This deserves special attention and should be considered when modelling fail-safe structural optimization with stress constraints.

这份简短的注释提出了一些关于在考虑构件特性局部退化的情况下进行故障安全结构优化时应力约束建模的观察。对三杆示例的分析研究表明约束模型选择对最佳设计的影响。一个值得注意的发现是，与完全删除该成员相比，一个任意成员的降级可能导致更差的目标函数。该观察类似于具有应力约束的拓扑优化中的奇异最优问题，但也适用于尺寸确定问题。这值得特别注意，在对具有应力约束的故障安全结构优化进行建模时应予以考虑。