SEDL / STP / STP893-EB / STP35356S

Characterization of Mode I and Mixed-Mode Failure of Adhesive Bonds Between Composite Adherends

Mall, S
Associate professor, University of Missouri, Rolla, MO

Johnson, WS
Research engineer, National Aeronautics and Space Administration, Langley Research Center, Hampton, VA

Pages: 13    Published: Jan 1986

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Abstract

A combined experimental and analytical investigation of an adhesively bonded composite joint was conducted to characterize both the static and fatigue debond growth mechanism under Mode I and Mixed-Mode I and II loadings. Two bonded systems were studied: graphite/epoxy adherends bonded with EC 3445 and FM-300 adhesives. For each bonded system, two specimen types were tested: (1) a double-cantilever-beam specimen for Mode I loading and (2) a cracked-lap-shear specimen for Mixed-Mode I and II loading. In all specimens tested, failure occurred in the form of debond growth. Debonding always occurred in a cohesive manner with EC 3445 adhesive. The FM-300 adhesive debonded in a cohesive manner under Mixed-Mode I and II loading, but in a cohesive, adhesive, or combined cohesive and adhesive manner under Mode I loading. Total strain-energy release rate appeared to be the driving parameter for debond growth under static and fatigue loadings.