A three-dimensional model of fatigue crack growth incorporating crack closure
Abstract
Experiments have shown that fatigue cracks remain closed during a portion of the load cycle. An analytical crack growth model has been developed by Newman to include this effect for a two-dimensional center cracked panel. The model has been shown to correlate well with experiments performed on aluminum alloys. This thesis attempts to calculate the closure that occurs in a three-dimensional surface crack by extending the principles employed in Newman's two-dimensional model. The surface crack model was used to analyze experiments performed on polymethylmethacrylate, a transparent polymer. The free surface closure values predicted by the model correlated well with most of the experiments. At the interior, the model predicted significant closure while very little was observed experimentally. Experimental observation also showed that the maximum displacement at minimum load did not occur at the crack mouth as the model assumed, but occurred well inside the crack.
Degree
Ph.D.
Advisors
Grandt, Purdue University.
Subject Area
Aerospace materials
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