Free edge and size effects on failure initiation and ultimate strength of laminates containing a center hole
Abstract
A failure analysis method that includes free edge and size effect was proposed for failure prediction in composite laminates containing a center hole. Categorically, this failure analysis consists of three major parts. The first is the size effect on the strength of an unnotched coupon specimen under off-axis loading. The relationship between ultimate strength and volume of the specimen was established by curve fitting the experimental results. From those test results, the strength of the composite laminate with respect to the dimension of the specimen was determined. After finding the relation between size and strength, the location of the onset of failure in the hole can be determined by comparing the strength of off-axis unnotched specimens with the hoop stress around the hole. The corresponding strength in this location was defined as the initial failure strength. From the specified failure location and stress, subsequent failure progression was performed by ply-by-ply classical laminate failure analysis in addition to free edge failure analysis of the laminate at the free surface of the hole. Experiments on (0/90/$\pm$45) $\sb{\rm s}$ and (0/90) $\sb{\rm s}$ laminates and their off-axis specimens were performed to verify the present method.
Degree
Ph.D.
Advisors
Sun, Purdue University.
Subject Area
Aerospace materials
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