Finite element modeling of crack growth in thin-wall structures by method of combining sub-partition and substructure

A combination of sub-partition and substructure methods in finite element is developed to simulate the crack propagation in plate and shell structures. This method allows modeling arbitrary shape crack independent of element mesh and only the elements overlapping crack need to be operated. An element cut apart by a crack is sub-partitioned into ordinary sub-elements while an element enveloping crack tip is sub-partitioned into several singular sub-elements. The whole sub-elements constitute a substructure and the additional nodal freedom degrees introduced by element sub-partition are condensed to nodes of original mesh. In this way global re-meshing is avoided when the crack grows or new crack nucleates. Good accuracy of the crack tip fields prediction and good adaptability of moving crack simulation by the proposed method are proven through designed examples.