恒应力速率下陶瓷材料的亚临界裂纹扩展模型

从断裂力学出发，利用阻力曲线（Ｒ曲线），建立了恒应力速率条件下陶瓷材料亚临界裂纹扩展模型．利用计算机数值计算，获得材料在动态载荷条件下，裂纹扩展速率Ｖ与应力强度因子Ｋ的关系（Ｖ－Ｋ曲线），并分析了动态疲劳现象的本质．此模型的中心思想在于将亚临界裂纹扩展分为相互独立的２个过程，即：裂纹瞬时局域失稳扩展和应力腐蚀．利用此模型，对Ｓｉ３Ｎ４陶瓷的动态疲劳特性作出的理论预测与实验结果趋势一致．

Model of Subcritical Crack Growth under Constant Stress Rate Condition

A subcritical crack growth model is developed under constant stress rate condition where the R -curve is used. The VK (velocity versus stress intensity factor) curves under dynamic loads were obtained from a computer numerical method. It is assumed that the fatigue process can be devided into two parts, namely: mechanical and stress corrosion. Using this method, the fatigue crack growth cha racteristics of Si 3N 3 material was analyzed.