巴西圆盘试样中心斜裂纹疲劳扩展轨迹的边界元模拟

FATIGUE PATHS SIMULATION OF A CENTER SLANT CRACK IN CRACKED BRAZILIAN DISK BY BEM

提出了一个平面弹性体多裂纹疲劳扩展模型.它主要涉及到复合型加载情况下多裂纹尖端疲劳扩展的数学模型及杂交位移不连续法(一种边界元法).在数值模拟中,对每一裂纹扩展增量分析时,在其先前的边界上增添裂纹扩展增量,且只对新增添的裂纹扩展增量划分单元,同时,按照这种边界元法的实施方法对一些单元特征进行调整,就可以方便地模拟裂纹扩展.用这种数值方法模拟了巴西圆盘试样中心斜裂纹疲劳扩展轨迹,数值结果说明了预报模型的有效性,揭示了裂纹体几何对疲劳扩展的影响.

This paper presents a prediction model for fatigue growth of multiple crack tips in a plane elastic plate. It mainly involves a theoretical model and a numerical method to investigate the fatigue growth of multiple crack tips under mixed-mode loading. The numerical method was adopted with a hybrid displacement discontinuity method （HDDM）, a kind of boundary element method. With the boundary element method, a crack growth problem of multiple crack tips can be solved in a single-region formulation. In the numerical simulation, crack extension is conveniently modeled by adding new boundary elements on the incremental crack extension to the previous crack boundaries. Menwhile, the element characters of some related elements will be adjusted. As an example, the present numerical approach is used to simulate the fatigue growth of a center slant cracked circular disk. The numerical results illustrate the validation of the prediction model and reveal the geometry effect of the cracked circular disk on the fatigue growth .