等离子涂层典型界面损伤与破坏的数值模拟

Numerical simulation of damage and fracture on typical interfaces of plasma sprayed thermal barrier coatings

基于界面损伤力学思想,提出了三结点界面单元的概念,和传统界面单元相比,具有能够表征任意形状界面法线方向的优点,将改进的单元通过ABAQUS的用户子程序UEL与有限元软件进行了结合.考虑等离子涂层界面粗糙度的影响,模拟了余弦形界面在热循环载荷下的损伤以及在拉伸载荷下的破坏过程.计算结果表明,界面单元结点间位移出现不连续现象,体现了裂纹的逐渐张开过程,界面损伤随热循环次数的增加而增加,其中第一个循环造成的损伤最大,波峰处是界面断裂的危险位置,法向分离起主导作用;等离子涂层粗糙界面承受法向拉伸载荷的能力较平直界面显著增加.采用改进的界面单元模拟异质材料复杂形状界面的损伤与破坏是可行的,结果是合理的.

Based on the idea of interface damage mechanics, a new type of interface elements with three nodes was proposed. Compared with traditional interface elements, these elements have the quality of indicating the normal direction of interface with arbitrary shape. The modified model was implemented into ABAQUS by user subroutine UEL. The numerical simulation of the damage and fracture for cosine shape interface were achieved considering the rough interface of the plasma sprayed thermal barrier coatings. The calculating results show that, under thermal cycle loadings, the displacement between nodes of the interface elements is not con- tinuous which represents the opening process of the interface crack, the damage increases with the number of thermal cycle loadings and the max damage is caused during the first cycle, the top of the interface is the critical position and the normal separation dominants, under uni-axial tension loadings, the wavy interfaces have better capability of load bearing than the linear interfaces for PS-TBC. Simulation of damage and fracture for different materials with arbitrary interface using the modified interface elements is available, and the results are reasonable.