基于疲劳累积损伤的弹塑性裂纹扩展分析

根据裂尖疲劳损伤累积导致材料破坏的观点，发展了一个弹塑性疲劳裂纹扩展模型.假设在裂纹前缘HRR场内存在一个高应变区，该区长度x*等于材料常数D、其塑性变程是△尹，由N区朋on公式求出对应于△a*的疲劳破坏循环数N白，则疲劳裂纹扩展速率就是x‘/N，。新模型建立了材料低周疲劳特性与弹塑性裂纹扩展规律之间的联系。由模型计算得到的弹塑性裂纹扩展速率与实验结果的比较表明，二者吻合良好。 

Analysis of Elastoplastic Crack Growth Based on Cumulative Fatigue Damage

A model of elastoplastic fatigue crack growth based on cumulative damage analysis near crack tip is developed. It is assumed that at the crack tip there exists a small highly strained area, the width of which X~* is equal to D defined by Hutchinson. Musuva's plane stress solution is used to calculate the plastic strain range in this area. For the known strain range the number of cycles N~* necessary for material failure is obtained from Manson's relation. Then the fatigue crack growth rate is calculated by the ratio X~*/N~*. The results are in good agreement with those from experiments.