基于奇异强度因子的V型切口应力场和N-SIF评估方法

Evaluation Method of V-notch Stress Field and N-SIF Based on Singular Intensity Factor

根据线弹性断裂力学理论,V形切口处的应力场具有奇异性,应力值趋于无穷大,峰值应力不能直接用于评定疲劳强度.通过引入了奇异强度因子“as”,单边缺口应力分布和缺口应力强度因子(N-SIF)的半解析公式被推导.考虑张开角和几何尺寸等因素,基于奇异强度因子拟合得到了切口应力评估的简易公式,可用于切口应力场和N-SIF值的快速评估.将简易公式评估结果与有限元结果以及传统文献结果进行对比分析,结果表明,论文简易公式可以准确地预报拉伸载荷下单边V型切口角平分线上的应力场和N-SIF值,实现了切口试样应力场的快速评估.

According to the theory of linear elastic fracture mechanics, the stress field at V-notch is singular, where the stress value tends to infinity, and the peak stress cannot be directly used to evaluate the fatigue strength. By introducing the singular intensity factor "as", the semi-analytical formulas of edge crack notch stress distribution and notch stress intensity factor(N-SIF) were derived. Considering the factors such as opening angle and geometric size, a simple formula of notch stress evaluation was obtained based on singular intensity factor fitting, which can be used to quickly evaluate the notch stress field and N-SIF value. Comparing the evaluation results of the simple formula with those of the finite element method and traditional literature, the results show that the simple formula in this paper can accurately predict the stress field and N-SIF value on the bisector of a single V-notch angle under tensile load, thus realizing the rapid evaluation of the stress fields of notch samples.