FAILURE ANALYSIS OF LAMINATED COMPOSITE ANGLES
Abstract
Laminated angles were studied to determine the failure mechanics. Analysis was performed using the finite element method. Additionally, several alternative analysis techniques were developed based on a strength of materials approach. Tests were conducted to obtain failure data for several different angle laminate stacking sequences. Specimens were fabricated using both graphite/epoxy and fiberglass/epoxy material systems. Two different failure modes, in-plane failure and out-of-plane, or delamination, failure, were found to occur in the angle laminate. Failure analysis was conducted using the Hill criterion, the Hill-Tsai criterion and the maximum radian stress criterion. The Hill-Tsai and maximum radial stress criteria were used together to predict in-plane and out-of-plane failures respectively. The Hill criterion was used to predict failure by either failure mode. Fracture mechanics analysis was utilized to study the relationship between in-plane and out-of-plane failure. It was determined that fracture mechanics could be used to predict the onset of delamination based on the branching of in-plane bending cracks. Finally, adhesive plies were studied as a means of preventing delamination in the curved laminate.
Degree
Ph.D.
Subject Area
Aerospace materials
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