Three-dimensional finite element analysis of free-edge delamination in composite laminate
Abstract
A 24 node, 64 degree-of-freedom solid hexahedronal finite element is used to analyze the free edge delamination of composite laminates. The large storage space problem frequently encountered in the modeling of contoured delamination problems is resolved by using the preconditioned conjugate gradient method. The advantage of this method is that there is no need to store the fill-in elements in the stiffness matrix decomposition process, which leads to a significant reduction in storage space required, thereby making the analysis of the complicated contoured delamination problem feasible as well as effective. To evaluate the accurateness of the present formulation, numerical algorithm and computer program, free edge stress analyses were performed for (0/90) $\sb{\rm s}$ cross-ply laminate, ($\pm$45) $\sb{\rm s}$ angle-ply laminate and ($\pm$25/90) $\sb{\rm s}$ laminate, each plate subjected to axial tensile strain loading. The present three-dimensional solutions were found in agreement with those found in a prior quasi-three-dimensional solution. To demonstrate the applicability of the present development, the strain energy release rate of a ($\pm$25/90) $\sb{\rm s}$ graphite-epoxy rectangular laminated plate subjected to tensile strain was then studied. An initial delamination of elliptical type was assumed to be located along the free edge at the middle of the thickness. The strain energy release rate along the delamination front was calculated using the modified crack closure method. The numerical results show that mode I strain energy release rate $G\sb{I}$ is distributed non-uniformly along the delamination front and reaches a maximum value at the free edge of the laminate.
Degree
Ph.D.
Advisors
Yang, Purdue University.
Subject Area
Aerospace materials|Mechanical engineering|Civil engineering
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