激光辐照热障涂层中平面应变问题的热弹性变分分析

Variational analysis on therm-elastical stresses of plane strain problem of thermal barrier coating structure in laser radiate

针对激光辐照热障涂层材料的平面应变问题,提出热障涂层热弹性分析的基本方程,对定常温度场给出级数形式解析解,并用最小余能原理和变分法分析了结构的热弹性应力场,研究了最大应力和界面应力的分布特征,并就一些物理参数的影响进行了讨论。结果表明,热障涂层的主要破坏因素为表面拉伸应力,界面应力相对较小,但在自由边界有集中现象,剥落应力大于剪切应力,是导致涂层破坏的重要原因。涂层厚度增加会改变厚度方向上的应力分布,界面应力向中心集中。

Present fundamental equations of thermoelastic deformation of thermal barrier coating (TBC) irradiated by laser in the condition of plane strain. Series solutions of steady temperature field are derived. Thermoelastic stress field in TBC is studied by means of variational principle of complementary energy. The distributed characters of maximal stresses and interfacial ones and the effects of some physical parameters on stresses are investigated. The results show that the main factor caused destroy of TBC is tensile stress. The interfacial stresses are comparatively feeble, but concentrate at the free edge. The peeling stresses are stronger than, shearing ones and are important reason for failure of coating. Increase of coating's thickness changes the distribution of stresses in the direction of thickness and makes interfacial stresses to concentrate toward the center of specimen.