Errors Estimation for Evaluating Mixed-Mode Stress Intensity Factors for Cracks Emanating from Sharp Notches Using Simulated Photoelasticity

In this paper, errors involved in extracting stress intensity factors from photoelastic fringe pattern, which were simulated for crack estimated. The estimated errors do not contain the errors associated with the optical apparatus, but only consist of the errors associated with discretization and extraction of data for SIF’s calculation to accomplish that. A series of fringe pattern were simulated for specimens containing various cracks in finite strips under remote tensile loading. In addition, by combination of fracture mechanics and photoelasticity’s equations and digital image analysis an algorithm is developed for determining stress intensity factors (SIFs). In addition, to utilize the advantage of "whole-field" photoelasticity and to minimize the random experimental errors, the over deterministic least-squares method of Sanford combined with Newton-Raphson method is used to obtain SIFs.