三维冲击荷载弹塑性弯曲裂纹张开位移

The Three-Dimensional Curved Elastic-Plastic Crack Tip Opening Displacement under Impact Load

主要研究冲击载荷作用下的三维弹塑性弯曲裂纹尖端的张开位移问题.综合考虑了冲击作用应力,三维塑性区域边界上正应力与剪应力,利用二阶摄动方法计算了三维弹塑性弯曲裂纹尖端的张开位移.用数值解法计算出三维弹塑性弯曲裂纹尖端张开位移,作图分析了三维弹塑性弯曲裂纹尖端张开位移与三维裂纹体几何尺寸之间的变化关系.三维弹塑性弯曲裂纹尖端张开位移随着三维裂纹体厚度的增大而减小,随着三维裂纹体厚度的均匀增大,三维弹塑性弯曲裂纹尖端张开位移尺寸不断减小,减小的幅度越来越小,最终趋于平面应变状态下的弹塑性弯曲裂纹尖端张开位移尺寸.当三维裂纹体几何尺寸相同时,三维弯曲裂纹尖端动态张开位移随外部冲击载荷的不断增大而逐渐增大,三维弯曲裂纹尖端动态张开位移随动荷系数的增大而迅速增大,建立了一个计算三维弹塑性弯曲裂纹尖端动态张开位移的崭新理论模型.

In this article, three-dimensional elastic-plastic curved crack tip opening displacement under impact load has been mainly studied, and three-dimensional curved crack tip opening displacement has been calculated using a second order perturbation method, where the effects of applied impact stresses as well as normal and shear impact stresses on the boundaries of plasticity area are taken into account. Three dimensional curved elastic-plastic crack tip opening displacement has been calculated by numerical methods. Diagrams have been constructed to analyze the transformation relationship between the curved crack tip opening displacement and the geometrical parameters of three-dimensional crack body. Curved crack tip opening displacement will decrease when three-dimensional crack body thickness increases. When crack body thickness increases uniformly, three-dimensional curved crack tip opening displacement will continuously decrease. Furthermore, the decrease will gradually slow down, and tend to plane strain state ultimately. Curved crack tip dynamic opening displacement will increase when the external impact load increases with the same crack body thickness. Curved crack tip dynamic opening displacement will increase abruptly when dynamic load coefficient increases with the same crack body thickness. A new theoretical model has been established to calculate the curved crack tip dynamic opening displacement for three-dimensional crack body.