Simulation of Fatigue Crack Propagation in 3D Shell Structures

In this contribution an efficient and modular method is presented to simulate fatigue crack propagation within the framework of linear-elastic fracture mechanics. The FEM code ABAQUS/Standard is used to simulate the load/displacement history of the considered 3D shell structure using 6-node triangular shell or continuum elements while the preprocessor ANSA is applied to employ remeshing. In order to efficiently simulate fatigue crack propagation in large finite element models a sub-model is extracted from the global model. The submodel is subjected to the kinematics given at the interface to the global model. Concerning fracture mechanics theory the stress intensity factor concept is applied. Stress intensity factors are calculated from the finite element mesh within an ABAQUS user subroutine using a novel variant of the well-known displacement correlation technique. Variable amplitude loading is accounted for by using a special counting algorithm and an averaging procedure to calculate the crack extension direction. In order to compute the number of load cycles various fatigue models have been implemented.

The adopted theoretical framework is outlined in the present article. Various validation examples demonstrate the capabilities and accuracy of the developed fatigue crack propagation simulation environment.