Finite element on determination of geometric correction factor for linear fracture mechanics

Abstract

In the context of fracture mechanics, geometric correction factor is an important factor that account for various geometries and crack configurations. The purpose of this report is to investigate the geometric correction factor for finite geometries that contains various crack configurations and loadings. Types of crack configurations include center crack, single-edge crack, and double-edge crack. In this final year project, finite element analysis is used to determine the stress intensity factor at the crack tip for the stated crack configurations. Subsequently, minor calculations are made to obtain geometric correction factor. The student version of ANSYS Mechanical APDL is used for the finite element analysis. Methodology of modelling various geometries and crack configurations are also provided in this report. A critical comparison of geometric correction factor generated using FEM versus the values predicted by empirical formulas is also presented. The computed values of geometric correction factors based on most of the empirical formulas available in the literature are close to that of FEM. Furthermore, as there is very little research that accounts for the height of the plate, analyses are conducted to understand its effect on geometric correction factor as the height and width ratio changes. The geometric correction factor increases with increase in crack length for all fracture problems considered in this project except the double-edge crack problem. In addition, as the height and width ratio increase, the geometric correction factor decreases. Apart from that, a comparison between 8-node quarter point elements and conventional elements is also presented to determine which yields accurate value of stress intensity factor for one of the fracture problems. In this case, the conventional elements yield better results.