Accumulated damage in fatigue creep interaction of aluminum 2024,T4

Dissertant

Majid, Mahir Hamid

University

University of Technology

Faculty

-

Department

Department of Electromechanical Engineering

University Country

Iraq

Degree

Ph.D.

Degree Date

2009

English Abstract

In some applications, the aluminum alloy 2024 may be subjected to an interaction of fatigue and creep effects at high temperature, The interaction may be due to a combined creep-constant amplitude fatigue effects or creep-variable amplitude fatigue effects.

This Study investates the effect of these interactions by studying the effect of constant amplitude fatigue (CAT), variable amptitutfc fatigue (VAF) by high cyclic fatigue technique, and creep separately, then fatigue-creep interaction Is introduced by testing the alloy under constant and variable amplitudes with some holding, time periods through the test at high temperature (150C). The results showed that the life time of the allay decreases due to fatigue-: creep interaction as compared to creep alone in about 77 %, and in about 80 % as : compared with fatigue alone.

This is a result of accumulated fatigue damage superimposed c-n creep damage.

Creep allows more free spaces for fatigue cracks paths that accelerate failure.

The variable; amplitude fatigue-creep interaction £ showed adecre-ase in lifetime as compared with constant amplitude fatigue-creep ' interaction in about 90 %. Theoretical models to calculate the time to failure due to fatigue-creep interactions have been proposed- These were time fraction model and Cavity growth model These theoretical interaction models predict very close time to failure values to the experimental results, so the difference can converges to zero- The time fraction model showed safer values than cavity growth model ; especially for the variable amplitude Fatigue creep interaction, so the variable amplitude interaction predicts lives, by cavity growth model lower man those which are predicts y Ume fraction model in about 45 %. Finally, interaction diagram a between creep damage and fatigue damage are presented, and the safe and unsafe design zones are identified..

Main Subjects

Civil Engineering

Topics

• Aluminum alloys

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305076