SYMPOSIA PAPER Published: 01 January 1988

Failure Mechanism of Delamination Fracture


The failure mechanism of delamination fracture in composites is investigated. A model based on the fracture mechanics principles is applied to describe the in situ delamination failure process. The crack tip plastic zone developed in the thin resin layer between fibers is considered as the major energy dissipation mechanism. The model expresses delamination fracture toughness GIc (laminate), Mode I critical strain energy release rate, as a function of several resin properties. The delamination behavior of several epoxy/fiberglass systems was characterized using the width-tapered double cantilever beam method. The GIc (laminate) results are correlated with the resin properties based on the in situ failure model. Resin modulus E and yield stress σy are found to dictate the translation from GIc (resin) to GIc (laminate. Residual stresses in the laminates can also significantly weaken the delamination resistance. A comprehensive comparison between laminate and resin fracture toughness reported in the literature is analyzed from the viewpoint of the mechanism modelled.

Author Information

Lee, SM
Composite Materials Department, Ciba-Geigy Corporation, Anaheim, CA
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Developed by Committee: D30
Pages: 356–365
DOI: 10.1520/STP26145S
ISBN-EB: 978-0-8031-5044-7
ISBN-13: 978-0-8031-0980-3