基于权函数法的应力强度因子计算和断裂评估

仅利用一个参考载荷,建立一种近似公式来计算共线裂纹和中心裂纹的张开位移。通过该方法确定的裂纹面张开位移及其偏导与精确解之间吻合良好。该方法将中心裂纹的权函数计算模型简化为形状因子和裂纹面张开位移偏导之间的积分。基于权函数法,研究了带中心裂纹的旋转叶片的应力强度因子与裂纹长度、位置、转速及转动加速度之间的关系。结果发现:应力强度因子随着裂纹长度的增加和裂纹与旋转轴间距的减小而增大;转动加速度对应力强度因子的影响较小;转速的增大会使应力强度因子增大。在断裂力学理论的基础上,建立了断裂控制准则,计算表明叶片的临界转速随着裂纹长度的增加而降低。

Stress intensity factor calculation and fracture evaluation based on weight function method

An approximate and simple expression was presented to calculate the crack face displacements of collinear cracks and center cracks by use of only one reference stress intensity factor. The crack face displacement and its partial derivative determined by the present method were in good agreement with the exact solutions. Calculations of the weight function for the center crack were reduced to the simple quadrature of the correction function and the partial derivative of the crack face displacement. Based on the weight function method, the relationships between the stress intensity factor of the rotating blade with a center crack and the crack length, crack location, rotating speed and angular acceleration were studied. It showed that the stress intensity factor increased with the increasing crack length and the decreasing distance from the crack line to the rotating axis; the influence of the angular acceleration was negligible, but the increasing rotating speed made the stress intensity factors increase. The critical rotating speed of the blade was evaluated based on the fracture law, and decreased with the increasing crack length.