Progressive crack growth analysis using interface element based on the virtual crack closure technique

This paper introduces an interface element to solve 2D progressive crack growth problems under mixed-mode loading. The interface element is developed to calculate the strain energy release rates based on the virtual crack closure technique (VCCT) in conjunction with finite element analysis (FEA). A very stiff spring is placed between the node pair at the crack tip to calculate the internal forces. Dummy nodes are introduced to extract information for displacement openings behind the crack tip and the virtual crack jump ahead of the crack tip. Therefore, with this interface element, strain energy release rates (GIGI and GIIGII) can be calculated simultaneously as FEA is performed. Furthermore, with the implementation of fracture criteria, crack growth can be also directly analyzed with a fracture mechanics approach. Three classic examples for stationary cracks and three benchmark examples for static crack growth were examined. The accuracy of the element is validated by the excellent agreement with analytical solutions of these examples. No convergence difficulty has been encountered during the crack growth analyses. The fracture interface element for VCCT is, therefore, simple, efficient and robust in analyzing any 2D crack growth problems. This element has been implemented into commercial FEA software ABAQUS®ABAQUS® with UEL and should be very useful in designing for enhanced structural integrity in general cases where crack initiation, crack growth, and crack arrest features are of concern.