塑性区阻止效应对三维裂纹应力强度因子的影响研究

On the Plastic Zone's Ameliorating Effect on the SIF of 3-D Crack

在应用片条合成法计算三维裂纹尖端应力强度因子基础上,推导了在小范围屈服情况下考虑塑性区影响时三维裂纹尖端应力强度因子的求解公式,讨论了塑性区大小对裂尖应力强度因子的影响,其中重点考虑了塑性区对裂纹发展的阻止效应.通过对结果进行分析和讨论,给出可供工程应用参考的依据.计算结果表明,在考虑了塑性区对裂纹发展的阻止效应后,大多数情况下塑性区修正使应力强度因子比未考虑塑性区修正的应力强度因子要小7%～30%.

We modify the slice synthesis method for constructing a weight function based strip-yield model for a semi-elliptical part-through surface flaw in an elastic-perfectly plastic body under monotonic loading. This model enables rapid approximate computation of the crack surface displacement and the crack front plastic zone size in the three-dimensional crack. On the basis of computing the stress intensity factor （SIF） of three dimensional crack with this modified slice synthesis method, we, considering the plastic zone＇s effect, deduce the formula of SIF of three dimensional crack front within the small yield scope, and discuss the effect of plastic zone size on SIF. We analyze and discuss the results. The calculation results show that after the plastic zone＇s effect on the growth of the crack is considered, the SIF will be less by 7%-30% compared with the case in which the effect is ignored. This reduction of 7%-30% may be of reference value in engineering design.