三维准静载弹塑性弯曲裂纹塑性区

PLASTICITY AREA AT THE THREE DIMENSIONAL CURVED ELASTICITY-PLASTICITY CRACK TIP UNDER QUASI-STATIC LOAD

主要研究准静载荷作用下的三维弹塑性弯曲裂纹尖端的塑性区问题。综合考虑了准静作用应力,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塑性区。用数值解法计算出三维弹塑性弯曲裂纹尖端塑性区于裂纹直线部分延长线上的投影长度,作图分析了三维弹塑性弯曲裂纹尖端塑性区尺寸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塑性区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塑性区尺寸。当三维裂纹体几何尺寸相同时,三维弯曲裂纹尖端塑性区尺寸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塑性区尺寸的崭新理论模型。

In this article,three dimensional elastic-plastic curved crack tip plasticity area under quasi-static loads has been mainly studied,and three dimensional curved crack tip plasticity area has been calculated as a practical application of a second order perturbation method,where the effects of quasi-static applied stresses and quasi-static normal and shear stresses on the boundaries of plasticity area are synthetically taken into considerations. Projected length of three dimensional curved elasticplastic crack tip plasticity area on straight crack extension line portion has been calculated by numerical solutions,diagrams have been constructed to analyse the transformation relationships between curved crack tip plasticity area size and three dimensional crack body geometrical measurement. Curved crack tip plasticity area size will decrease when three dimensional crack body thickness increases. When crack body thickness increases evenly,three dimensional curved crack tip plasticity area size will continuously decrease,furthermore,the decrease extent will be more and more slightly,and tend to plane strain state ultimately.Curved crack tip plasticity area size will increase when external loads increase with the same crack body thickness. A new theoretical model where curved crack tip plasticity area size was calculated has been established in three dimensional crack body.