Characterization of the Microstructure and Surface Roughness Effects on Fatigue Life Using the Tanaka-Mura-Wu Model

Additive manufacturing (AM) has drawn tremendous interest in engineering applications because it offers almost unlimited possibilities of innovative structural design to save weight and optimize performance. However, fatigue properties are one of the limiting factors for structural applications of AM materials. The recently developed Tanaka-Mura-Wu (TMW) model is modified to include the microstructure and surface roughness factors, in addition to the material's elastic modulus, surface energy and Burgers vector, to predict the fatigue curves as functions of stress or plastic strain for several typical AM materials as well as their conventional (wrought) counterpart. Furthermore, with statistical characterization of the microstructural effect, the model can be established to evaluate fatigue design allowables.