Determination of Fracture Parameters From Numerical Isochromatic Plots Using Multiparameter Approach

ABSTRACT Fracture parameters such as stress intensity factors (SIFs) and T ‐stress are fundamental metrics for analysing material failure. Of late, there has been increased use of both experimental and numerical methods in analysing and validating the solutions for complex problems. Both domains can benefit from exploring methods developed in either of them to effect meaningful comparisons and solve certain new problems. Consequently, developing alternative methods for evaluating SIFs from numerical models is desirable in fracture mechanics. In this paper, a novel method is developed that involves post‐processing numerical results to evaluate and plot ( σ 1 – σ 2 ) stress contours ( isochromatics ) towards fracture parameter evaluation. The isochromatic plots serve as a qualitative tool for assessing mode dominance, mode mixities and facilitate easy comparison with experiments to validate numerical modelling. Fracture parameters are determined by over‐deterministic least squares approach from the isochromatics plotted, based on photoelastic literature. The method is initially validated for standard cases by comparing the values obtained with handbook solutions which show a good match within 3.6% and are consistent with FE results. This is followed by application of the method to problems having interaction of crack‐tip with contact stress fields in the vicinity. Usually, finite element method facilitates direct evaluation of fracture parameters only for sharp cracks. The methodology developed is also shown to be useful to get SIFs for cracks having a finite root radius after validating the isochromatics from numerical models using photoelastic experiments.