采用包络-准则法优化考虑瞬态传热的薄板结构

刚度和强度是薄板结构的两个主要性能。在瞬态传热过程中,考虑热-力耦合,随时间和空间变化的非均匀温度场在结构中会引起热变形和热应力,温度场随时间变化的规律和空间分布依赖于板的厚度变化,进而影响板的刚度和强度。因此,考虑瞬态传热的薄板优化问题具有更强的非线性,更加难以求解。本文给出一种包络-准则方法处理这类结构优化问题。首先,针对外力荷载,进行一个结构柔顺性的优化设计;以这一设计为基础,通过瞬态热-力耦合分析及优化准则,计算多个时刻的优化设计变量并取其包络,对上述优化结果进行迭代修正,以消除瞬态温度场作用下较高的局部应力。优化算例表明,该方法对于考虑瞬态传热薄板优化问题有效。

An envelope-criterion method for thin plate optimization under a transient heat transfer process

Stiffness and strength are main performance indicators of thin plate structures.In a transient heat transfer process,considering thermo-mechanical coupling,the temperature distribution is nonuniform and time variant,resulting in thermal deformations and thermal stresses in a structure.The variation of a temperature field depends on the thickness of the plate,and affects the stiffness and strength of a plate. Hence,the complex influence of the temperature field makes the optimization problem more nonlinear and more difficult to solve.In this paper,an envelope-criterion method is presented to deal with the structural optimization with such a complex temperature field.First,a structural compliance optimization design is carried out for external loads. Based on this design,by calculating multiple time index functions and taking the envelope,the above optimization results are modified iteratively to eliminate the higher local stress under transient temperature field.Some numerical examples are given and the results show that the method is effective for thin plate optimization in a transient heat transfer process.