对称型陶瓷层状复合材料中的残余应力分析

针对由层间约束引起的层内残余应力，提出了用于描述层合材料应力应变状态的非均匀应变模型。利用非均匀应变模型推导出对称型层合材料由层间约束引起的层内残余应力的解析表达式，得到层内应力和界面应力沿长度方向分布的变化规律，指出轴向残余应力是层间界面剪应力造成的，是位置的函数；论证了由于表层材料受力的非对称性，界面必定存在正应力，且界面正应力须自平衡，界面正应力亦为长度方向上位置的函数，针对Si3N4-Si3N4/TiN-Si3N4三层及多层（2N＋1）对称型陶瓷基层状复合材料，研究了残余应力对强界面结合的层合材料宏观力学性能和裂纹扩展行为的影响和作用。结果表明，材料的宏观性能随着残余应力的变化而变化，其变化规律与理论计算的结果吻合。

RESIDUAL STRESS AND INTERFACE STRESS IN SYMMETRIC LAMINATED COMPOSITES

An uneven strain model for analyzing the residual stress and interface stress in laminate composite was proposed. The analytic formulas of residual-stress in the laminate with symmetrical structure were presented and the variations of the residual-stress and interface stress with location were studied. This study revealed two important facts: (1) for a single layer in laminate, the residual stress is a function of location along length; (2) there exist normal stresses in the interface and it varies along the length direction. Experiments of mechanical properties were performed, using Si3N4-Si3N4/TiN-Si3N4 laminate sample with symmetrical three-layer and multilayer (2N+1), to investigate the effect of residual stress. The results suggest that the mechanical properties depend on the distribution of residual stress and is consistent with the theoretic prediction.