曲线翼型裂纹扩展路径理论分析及试验验证

Study of curved wing crack path by theory and testing methods

采用数值和试验的方法对翼型裂纹的扩展路径进行分析,发现单轴下张开型裂纹的翼型裂纹的扩展路径逼近于过原主裂纹中心点、平行于最大主应力的一条直线。基于翼型裂纹路径这个特点,采用了双曲线参数方程近似表达真实翼型裂纹的扩展路径,通过翼型裂纹的起裂角、起裂点及翼型裂纹的渐近线方程求解了双曲线方程中的未知参数。采用双曲线翼型裂纹路径和试验中所得翼型裂纹路径进行了对比分析,二者吻合得很好,验证了采用双曲线近似表示真实存在的翼型裂纹模型的正确性。应用双曲线翼型裂纹模型对翼型裂纹的扩展和失稳进行分析,采用ABAQUS求解了双曲线翼型裂纹模型的应力强度因子,并与试验进行对比,发现双曲线翼型裂纹模型能很好地解释翼型裂纹的实际扩展规律,这表明了采用双曲线近似表示真实翼型裂纹路径的有效性。

Based on the research of the propagation paths of the wing cracks under uniaxial compression by the methods of experiments and numerical simulation. It is found that the wing crack extend along a curved path and gradually approximate to the line which passes the middle point of the main crack and is parallel to the direction of maximum principal stress. According to the geometric characteristics of the wing crack paths, a hyperbolic equation is set up to describe the curved paths of wing cracks approximately. In the equation, the unknown parameters are determined by the crack initiation angle, the crack length and the angle between the direction of the maximum principal stress and the crack surface. Then the comparative analysis of the paths by the hyperbolic equation and the experiments is made; and the results show that the paths by the hyperbolic equation are in concordance with those by experiments, so as to prove that the hyperbolic equation can be used to describe the propagation paths of wing cracks under compression. Furthermore, the stress intensity factors along the hyperbolic path are calculated by ABAQUS; then the extending loads of the wing cracks are analyzed. Through comparing with the experiment results, it is found that the extending loads by the hyperbolic wing cracks fit better with ones by the experiments so as to show validity of the results in the paper.