Fatigue life prediction of beam structures with breathing cracks using finite element analysis

This study presents a numerical procedure for estimating the fatigue life of cracked beams subjected to two-dimensional (2D) and three-dimensional (3D) direct and/or base excitations. A finite element (FE) model is developed for a cracked beam, in which the stiffness matrix of the beam element containing a breathing crack is formulated based on its strain state. Using this model, the stress intensity factor is computed for each vibration cycle, accounting for the breathing behavior of the crack. Fatigue crack growth increments are then evaluated using Walker’s equation to determine the total crack growth life and the maximum stress intensity factor. The fatigue status of the beam is assessed using three defined failure criteria. The proposed computational procedure is validated through two case studies involving a simply supported beam and a fixed-fixed beam, both containing breathing cracks. The maximum prediction error compared with experimental results is 7.91 %, demonstrating the method’s high accuracy. This work provides an effective and generalizable FE-based framework for fatigue life prediction of dynamically loaded beam structures with breathing cracks.