Approximations for Stress-Intensity Factors and Crack Propagation of Box Beams

The stress-intensity factors of box beams under torsion and crack propagation under torsion or/and bending moment are discussed here. This study is motivated by a previous work [1] that derived a closed-form expression of the mode II stress-intensity factor for thin-walled beams with a centered longitudinal crack and subjected to torsion. Naturally, the way in which mode I stress-intensity factors are influenced by torsion is of interest. The influence of parameters such as crack length, crack angle, width and depth of beam, wall thickness, and stiffener size on mode I and mode II stress-intensity factors has been studied using the finite element method and represented the data in a surrogate model using two approaches: 1) a Fourier-series-based correction factor, and 2) an artificial neural network. The crack propagation is also of interest. Specifically, the crack propagation study focuses on both the limit loadings and the angle in which the initial crack growth occurs.