Computation of Linear Elastic and Elastic Plastic Fracture Mechanics Parameters Using FEA

Abstract

Linear Elastic Fracture Mechanics (LEFM) parameter Stress intensity factor and Elastic Plastic Fracture Mechanics (EPFM) parameter J-Integral are the most imperative fracture parameters used to determine the structural integrity of components with flaws. This work deals with the evaluation of Stress intensity factor and J-integral for Center Cracked Tensile (CCT) specimens using the versatile Finite Element Analysis (FEA) package ANSYS. Alternate methods used for evaluating stress intensity factor such as stress extrapolation method and displacement extrapolation method have also been demonstrated. Different aspect ratios have been selected for the evaluation. The FEA results have been compared with that obtained by empirical means. An attempt has also been made to compute the critical crack length of a CCT specimen with a center through crack. Evaluation of critical crack lengths have been made under different loading cases, purely with the aid of FEA package ANSYS. J-integral evaluation depends on material non-linearity. The material curve for non-linear analysis have been generated using inverse Ramberg-Osgood relationship. ASTM A 36 steel used for common structural and plate applications is designated as the material for analysis. The ability of FEA to determine the fracture parameters has been successfully studied by this work.