SYMPOSIA PAPER Published: 01 January 1992

Delamination Failure in a Unidirectional Curved Composite Laminate


Delamination failure in a unidirectional curved composite laminate was investigated. The curved laminate failed unstably by delaminations developing around the curved region of the laminate at different depths through the thickness until virtually all bending stiffness was lost. Delamination was assumed to initiate at the location of the highest radial stress in the curved region. A closed form curved beam elasticity solution and a two-dimensional finite element analysis (FEA) were conducted to determine this location. The variation in the strain energy release rate, G, with delamination growth was determined using the FEA. A strength-based failure criterion adequately predicted the interlaminar tension failure that caused initial delamination onset. Using the G analysis, the delamination was predicted to extend into the arm and leg of the laminate, predominantly in Mode I. As the initial delamination grew around the curved region, the maximum radial stress in the newly formed inner sublaminate increased to a level sufficient to cause a new delamination to initiate in the sublaminate with no increase in applied load. This failure progression was observed experimentally.

Author Information

Martin, RH
Analytical Services and Materials, Inc., Hampton, VA
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Developed by Committee: D30
Pages: 365–383
DOI: 10.1520/STP20170S
ISBN-EB: 978-0-8031-5184-0
ISBN-13: 978-0-8031-1426-5