SYMPOSIA PAPER Published: 01 January 2000

A Plate Element-Based Model for Mixed-Mode Debonding of Composite Stitched Stiffened Panels


An analysis based on plate finite elements and the virtual crack closure technique is used to study the effect of stitching on Mode I and Mode II strain energy release rates for a stitched warpknit composite debond configuration. The stitches were modeled as discrete nonlinear fastener elements with a compliance determined by experiment. The axial and shear behavior of the stitches was considered with both the compliances and failure loads assumed to be independent. The effect of model slenderness ratio on the accuracy of the strain energy release rates determined with the plate element models for configurations without stitching was determined by comparison with similar plane strain models. The analysis showed that stitches are very effective in reducing Mode I strain energy release rate, GI by closing the debond faces near the debond front; however, they are less effective in reducing the Mode II strain energy release rate, GII.

Author Information

Glaessgen, EH
NASA Langley Research Center, Hampton, VA
Raju, IS
NASA Langley Research Center, Hampton, VA
Poe, CC
NASA Langley Research Center, Hampton, VA
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Developed by Committee: E08
Pages: 456–472
DOI: 10.1520/STP13420S
ISBN-EB: 978-0-8031-5418-6
ISBN-13: 978-0-8031-2617-6