Compliance evolution in round cracked bars under tensile fatigue

This paper studies the dimensionless compliance in cylindrical geometries with transverse surface cracks subjected to axial tensile loading. Compliance evolution is analyzed when round bars are subjected to fatigue with free and constrained sample ends, initial crack geometries of straight or circular fronts and several materials characterized through of the Paris parameter m. With this aim, a computer application that calculates the crack front’s geometric evolution and the dimensionless compliance was made by discretizing the crack front and assuming that every point advance perpendicular to the crack front according to the Paris law. The results show that dimensionless compliance grows with the increase of the relative crack depth and the decrease of the aspect ratio, showing greater values for free sample ends than for constrained sample ends. Furthermore, during fatigue crack growth, materials with higher values of the Paris parameter m produce slightly greater dimensionless compliance and a better convergence between the results for straight or circular initial crack.