三维疲劳弹塑性弯曲裂纹塑性区研究

Plasticity Area at the Three Dimensional Curved Elasticity-Plasticity Crack Tip under Fatigue Load

主要研究疲劳载荷作用下的三维弹塑性弯曲裂纹尖端的塑性区问题.用数值解法计算出三维弹塑性弯曲裂纹尖端交变塑性区于裂纹直线部分延长线上的投影长度的最大值和变化幅值,作图分析了三维弹塑性弯曲裂纹尖端交变塑性区尺寸的最大值和变化幅值与三维裂纹体几何尺寸之间的关系.三维弹塑性弯曲裂纹尖端交变塑性区的最大值和变化幅值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塑性区的最大值和变化幅值不断减小,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塑性区尺寸最大值和变化幅值.当三维裂纹体几何尺寸相同时,三维弯曲裂纹尖端塑性区的最大值和变化幅值随外载荷的不断增大而逐渐增大.建立了一个计算三维弹塑性弯曲裂纹交变塑性区的最大值和变化幅值的崭新理论模型.

This article mainly studies three dimensional curved elastic-plastic crack tip plasticity area under fatigue loads Specifically, the maximum value and variation amplitude of the length of the alternating plasticity zone near the crack tip projected on the extension line of the straight crack portion has been calculated by numerical solutions. Diagrams have been plotted to demonstrate the relations between the crack tip alternating plasticity zone size and the three dimensional crack body size. The maximum value and variation amplitude of the crack tip plasticity zone size will decrease when the three dimensional crack body thickness increases. As the body thickness increases, the decrease of the crack tip plasticity zone size will slow down and finally converge to the case of plane strain state. In addition, the crack tip plasticity zone size will increase with the applied load when the crack body thickness is kept constant. A new theoretical model has been established to calculate the maximum value and variation amplitude of the crack tip plasticity zone for the three dimensional elastic-plastic curved crack.