Author

Goswami

Date of Award

12-2004

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

In damage tolerant designs, it is important to know the crack growth behavior of a material, so that sudden failure of a component can be avoided by determining a safe life. There are numerous models available to predict the crack growth rate. Among them the "crack closure model" is most often used for predicting the crack growth rate for different R-ratios and load interaction effects. However recently, the crack closure model has come under criticism by many authors to be flawed and overrated owing to its inherent drawbacks.

Therefore, a mathematical model for the fatigue crack propagation based on damage accumulation process ahead of the crack tip has been developed, which utilizes stress and strain distribution ahead of the crack tip, modeled using Rice and elastic solutions. The methodology is based on the use of both Kmax and ∆K as contributing parameters to the driving force and damage accumulation.

Weight function approach has been adopted to determine the Kres profile. Load interaction and overload effects have been modeled by the effect of Kres on the Kmaxand ∆K. The predictions made by the model have been compared to experimental data and reasonable agreement has been found.

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