Fatigue fracture criteria and microstructures of magnesium alloy plates

Due to its close proximity to realistic conditions in engineering structures the angled crack problem has been given special attention in the recent years by fracture mechanics investigators. In this study, experimental and theoretical investigations were conducted to characterize the fatigue crack propagation in rectangular AM60B magnesium alloy plates containing an inclined through crack. The inclined angle of the crack with respect to the axis of loading was varied between 0 degrees and 90 degrees. The von Mises yield criterion is applied to define the plastic zone, instead of assuming a circular shape plastic zone with a constant radius. The commonly employed fracture criterion, the minimum strain energy density criterion, is modified by adopting the von Mises elasto-plastic boundary. The threshold condition of fracture is also established based on the experimental data. Finally, the influence of material microstructures on fatigue crack growth is assessed using the scanning electron microscope (SEM). (C) 2007 Elsevier B.V. All rights reserved.