Liu Wei, Li Longkang, Qiao Yaxu
Appl Opt. 2021 Feb 20;60(6):1489-1499. doi: 10.1364/AO.416708.
In this study, the digital gradient sensing (DGS) method is extended to determine the local stress fields at the blunt V-notch tip. Completely analytical expressions for angular deflections of light beams in the vicinity of the blunt V-notch tip are deduced based on Filippi's stress equation. Under plane stress conditions, the patterns of angular deflection related to two orthogonal stress gradients are theoretically plotted, and the effects of notch angle and notch radius are synthetically investigated, respectively. New procedures for the evaluation of local stress components and generalized notch stress intensity factor (NSIF) are presented using the experimental patterns of angular deflection contours. The NSIF values at the blunt V-notch tip in polymer materials with different geometric parameters under three-point-bend loading conditions are extracted from the DGS measurements. A good agreement is observed between the experimental data and the finite element simulations, which can verify the effectiveness and accuracy of the proposed DGS method.
在本研究中，数字梯度传感（DGS）方法被扩展用于确定钝V型缺口尖端处的局部应力场。基于菲利皮应力方程推导了钝V型缺口尖端附近光束角偏转的完全解析表达式。在平面应力条件下，理论上绘制了与两个正交应力梯度相关的角偏转图案，并分别综合研究了缺口角度和缺口半径的影响。利用角偏转轮廓的实验图案，提出了评估局部应力分量和广义缺口应力强度因子（NSIF）的新程序。从DGS测量中提取了三点弯曲载荷条件下不同几何参数的聚合物材料钝V型缺口尖端处的NSIF值。实验数据与有限元模拟结果吻合良好，验证了所提出的DGS方法的有效性和准确性。
