含弧形裂纹复合陶瓷强度的尺度效应

认为含弧形裂纹复合陶瓷由随机方向的三相胞元与有效介质构成,用细观力学的方法研究了复合陶瓷的损伤失效和强度。首先确定三相胞元的外载应变,再依据复合陶瓷在损伤过程中的细观应力场和广义热力学力,计算出三相胞元内基体和颗粒的损伤等效应力,当基体和颗粒的损伤等效应力分别等于两者的极限应力时,得到基体和颗粒的破坏应力。然后,根据混合型应力强度因子计算弧形裂纹扩展时的能量释放率,进而得到界面的破坏应力。最后综合考虑基体、颗粒和和界面损伤影响,获得含弧形裂纹复合陶瓷的宏观强度及其尺度效应。

Size dependent strength of composite ceramic with arc-cracks

The composite ceramic with arc-cracks was simplified to the random three phase cell and effective medium.The strength and damage of composite ceramic were researched by micro-mechanics.Firstly,the external strains of three-phase cell is determined.Then based on the micromechanical stress field and generalized thermodynamic force in damage process,the damage equivalent stress in the matrix and particle can be computed.As the damage equivalent stresses of the matrix and particle are equal to the ultimate stresses of the matrix and particle respectively,the fracture stresses of the matrix and particle in composite ceramic will be given.Finally,the strain energy release rate of arc-crack is computed by mixed-mode crack stress intensity factor,and the failure stresses of interface can be further gotten.At last,the size dependent strength of composite ceramic with arc-cracks is obtained by considering comprehensive damage effect of matrix,particle and interface.