Author

Tsutsui

Date of Award

6-2008

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

Department

Mechanical and Aeronautical Engineering

First Advisor

Dr. Daniel Kujawski

Second Advisor

Dr. Judah Ari-Gur

Third Advisor

Dr. Philip Guichelaar

Access Setting

Masters Thesis-Open Access

Abstract

A theoretical crack growth study on powder metallurgy aluminum alloys AA5091 and AA8022 was conducted. Specifically, the research focused on the crack growth retardation due to the application of a tensile overload. The tensile overload creates a plastic zone ahead of the propagating crack tip that induces the compressive residual stress after unloading. Such compressive residual stress pushes the crack tip faces against each other, which results in crack growth retardation.

In the study, simulation started from the calculation of the compressive residual stress. The details of the calculation steps are explained in the thesis. Eventually, the stress intensity factor range at the crack tip (∆Ktip) and the maximum stress intensity factor as the crack tip (Kmax tip) were calculated. These two parameters, along with constants C, m, and p, were used to simulate the crack growth rate.

Within the scope of the two-parameter (∆K, Kmax) approach, seven different calculation methods were investigated. The crack growth rate from each method was compared against experimental results from open literature. Finally, the best method among seven was determined.

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