幂硬化对疲劳弹塑性弯曲裂纹塑性区的影响

摘要

利用二阶摄动方法计算硬化材料弹塑性弯曲裂纹尖端的塑性区尺寸的最大值和和变化幅值。作图分析弹塑性弯曲裂纹尖端塑性区尺寸最大值、变化幅值与材料硬化指数之间的变化关系。在幂硬化材料中，弹塑性弯曲裂纹尖端塑性区尺寸最大值和变化幅值随材料硬化指数n的增大而减少，当n等速均匀增加时，弹塑性弯曲裂纹尖端塑性区尺寸最大值和变化幅值加速减少，减少的幅度越来越大。当材料的硬化指数相同时，弯曲裂纹尖端塑性区尺寸最大值和变化幅值随疲劳载荷的不断减小而逐渐减小。%Elastic-plastic curved crack tip plasticity area in hardened material under fatigue loads was mainly studied,and maximum and amplitude of curved crack tip plasticity area was calculated as a practical application of a second order perturbation method,where the effects of fatigue applied stresses and fatigue normal and shear stresses on the boundaries of plasticity area were synthetically taken into considerations. Diagrams were constructed to analyze the transformation relationships between maximum or amplitude of curve crack tip plasticity area size and hardening exponents.Maximum and amplitude of curved crack tip plasticity area size will decrease with hardening exponents increasing in hardened material.The decrease extent of maximum and amplitude of curved crack tip plasticity area size will be more and more severe with hardening exponents increasing evenly.Maximum and amplitude of curve crack tip plasticity area size will decrease when maximum and amplitude of fatigue loads decrease with the same hardening exponents.A brand new domain of theoretical model where fatigue curved crack tip plasticity area was calculated was reclaimed in hardened material.