表面涂层材料终止于界面裂纹尖端弹塑性奇异应力场

Elastic-plastic Stress Singularities Near the Tip of a Crack Terminating at the Interface of Film Coated Materials

针对涂层材料分析了终止于界面的裂纹尖端弹塑性应力场奇异性。由线性硬化全量理论并考虑到裂纹尖端应力奇异特征,建立了相关的本构方程。利用Goursat应力函数求得了裂纹尖端弹塑性奇异应力场。分析结果表明,所得应力场奇异性可以通过两个与硬化系数相关的Dundurs参数进行描述。当硬化系数远小于弹性模量时,奇异应力场仅需要一个Dundurs参数来表征。对于涂层为陶瓷基体为金属的情形,奇异性取决于裂纹方向。

The elastoplastic stress singularities are investigated, for a film coated material with a crack meeting the in-terface. Based on the assumption of the stress singularity at the crack tip, the constitutive equations are proposed through the total strain theory. The elastoplastic singular stress field is obtained by using Goursat stress functions. The analytic solutions show that the elastoplastic singular stress field can be generally described with two extended Dundurs parameters related to the hardening coefficients. In the case when the linear hardening coefficient is far less than the shear elastic modulus,only one extended Dundurs parameter is needed. In the case ceramic film deposited on the metal surface,the singularity is only determined by the direction of the crack.