Fracture analysis of mixed mode elliptic surface cracks in a plates under distributed load with FCPAS

Keywords: Fracture Mechanics, Stress Intensity Factor, Mode-I, Mode-II, Mode-III, Plate, Finite Element Method. One of the mechanical problems encountered in engineering designs is the breakage of structures or parts. It is necessary to calculate stress intensity factors using fracture mechanic approach on elastic structures for safe designs and to predict crack growth life. In practice, cracks can be observed on plate-like structures or they can be modelled locally as a crack in a plate. In this thesis, three dimensional mixed mode stress intensity factors of inclined and deflected surface cracks in plates subjected to axial stress or bending moment are calculated for a wide range of parameter values defining the problem. Stress intensity factors are calculated by using FCPAS (Fracture and Crack Propagation Analyses System) and a large stress intensity factor library is generated. The effect on stress intensity factors by changes on parameters such as crack depth /plate thickness (a / t), crack aspect ratio (a / c), angle of inclination and deflection of the elliptic crack with horizontal axis are investigated. In addition, for the generated solutions to be used more widely in practice, empirical equations have been developed for the stress intensity factors obtained from the detailed analyses as functions of the parameters affecting the problem and they have been further validated by independent case studies.