Mixed-mode fracture & non-planar fatigue analyses of cracked I-beams, using a 3D SGBEM-FEM Alternating Method

In the present paper, computations of mixed mode stress intensity factor (SIF) variations along the crack front, and fatigue-crack-growth simulations, in cracked I-beams, considering different load cases and initial crack configurations, are carried out by employing the three-dimensional SGBEM (Symmetric Galerkin Boundary Element Method)-FEM (Finite Element Method) Alternating Method. For mode-I cracks in the I-beam, the computed SIFs by using the SGBEM-FEM Alternating Method are in very good agreement with available empirical solutions. The predicted fatigue life of cracked I-beams agrees well with experimental observations in the open literature. For mixed-mode cracks in the web or in the flange of the I-beams, no analytical or empirical solutions are available in the literature. Thus mixed-mode SIFs for mixed-mode web and flange cracks are presented, and non-planar fatigue growth simulations are given, as benchmark examples for future studies. Moreover, because very minimal efforts of preprocessing and very small computational burden are needed, the current SGBEM-FEM Alternating Method is very suitable for fracture and fatigue analyses of 3D structures such as I-beams.