The effect of dwell loading on the small fatigue crack growth at notches in IN100

Date of Award

2012

Degree Name

M.S. in Materials Engineering

Department

Department of Chemical and Materials Engineering

Advisor/Chair

Advisor: Charles Browning

Abstract

Dwell loaded components are common in the turbine engine section of gas turbine engines. The turbine components are subjected to high stresses and high loads for up to 2 min during a pilots take-off, cruise and landing. Understanding the mechanisms of crack initiation while the turbine components are subjected to dwell loading is essential for fatigue life predictions. Previously conducted research includes the fatigue testing and life prediction of dwell specimens with an evenly distributed stress that is representative of a smooth location on the turbine disk. However, turbine disks have notches and fillets that change the stress concentration. This thesis utilizes the techniques and testing strategies that have been successful in predicting fatigue life in smooth bar dwell specimens and applies them to dwell notched specimens that are more representative of actual fielded components. The notch fatigue study indicates that the minimum fatigue life prediction method is applicable for various geometries and therefore, its applicability to actual fielded components holds reasonable promise.

Keywords

Surface roughness Cracking, Stress concentration, Turbines Parts Fatigue, Engineering; materials science; dwell; transgranular; intergranular; fatigue; small crack growth; fractography

Rights Statement

Copyright © 2012, author

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