Date of Award:

5-2011

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Mechanical and Aerospace Engineering

Advisor/Chair:

Yibin Xue

Abstract

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.

Comments

This work made publicly available electronically on May 11, 2011.

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