Numerical investigation of crack propagation in ship structures using extended finite element method

Abstract

Crack propagation is very detrimental to ship safety as it impairs structural integrity leading to catastrophic damage. In this study, simulation of crack propagation around hatch corner of a container ship has been done using Extended Finite Element Method (XFEM). An existing through-thickness crack at the hatch corner has been considered under tensile load arising from the combination of still water bending moment and wave bending moment in hogging condition. Crack lengths are varied for two different orientations to identify whether the crack starts to propagate under the design load. Effect of insert plate and hatch opening shape on the crack propagation are also investigated. XFEM-based cohesive segment approach has been employed for the simulation. Conservativeness of the numerical model has been examined by means of tensile tests of steel specimens having notch and hole. The advantage of XFEM regarding the avoidance of remeshing is well-utilized for the simulation of crack propagation in ship structures. It is found that increased thickness of insert plate is not beneficial to resist the propagation of an existing crack rather affecting the crack propagation negatively. While comparing the shape of hatch opening, elliptical opening can be better than circular opening.