Micromechanical Simulation for Fatigue Damage Incubation

Micromechanical simulations are conducted to quantify the influence of microstructure attributes to the formation of small fatigue cracks. Three wrought aluminum alloys (7075-T651, 2024-T3, virtual material) with fractured particle are studied to quantify the influence of material���s yield strength and ultimate strength to material���s fatigue resistance. Laser Engineered Net Shaping (LENS) material with pores of various spatial distribution and particles are simulated for the microplasticity and its effects on fatigue incubation. A cohesive zone model is used to study the interface cohesive behavior���s influence to the cyclic driving mechanisms. Different simulations based on different interfacial crack geometries and particle shapes are studied. A cohesive law with unloading-reloading cyclic behavior is introduced. A damage factor D is proposed to study the possibility of interfacial crack propagation. With this factor, plastic wake zone behind the debonding is studied.