NUMERICAL INVESTIGATION OF CRACK GROWTH IN METALS AND COMPOSITES

This work presents the simulation study of fracture behavior of steel and composites. The crack growth behavior of the material is simulated by extended finite element method (XFEM). XFEM allows the modeling of arbitrary geometric features independently of the finite element mesh. The crack surface elements are enriched by Heaviside function whereas, crack front elements treated by asymptotic functions. Ramberg-Osgood material model coupled with damage is used to simulate the crack propagation. The experimental data is obtained from extensive literature review of literature published in last five years. Numerical simulation is performed on the commercial software ABAQUS. A benchmark test specimen is used for numerical simulation, created as per ASTM standard in ABAQUS. 3D CT, SENB and DENT specimen have been chosen for simulation. The study aims at further extensive detailed study of fracture mechanics' design. Fatigue has been studied as mode 1 loading. Conformal meshing limitations with dynamic problems using classical FEM have been addressed. Paris law has been used as damage model. Mode I fatigue loading is used to analyze the crack growth in the both steel and composite problems. A specimen with initial crack is loaded till failure and therefore fracture mechanics design is extended to newly introduced class of materials. Number of cycles till failure is evaluated and visualized. The design considerations are further evaluated using benchmark literature tests like four-point bend and compression-tension tests. The knowledge has been extended to solve some practically important problems like turbine disk and surface cracking. A design feature leak before break has been given due consideration by solving the problems with high pressure pipes with internal cracks.