SEDL / STP / STP1290-EB / STP38227S

Direct Observation of Debonding in Fiber Pull-Out Specimens

Piggott, MR
Professor Emeritus and graduate student, University of Toronto, Toronto,

Xiong, Y
Professor Emeritus and graduate student, University of Toronto, Toronto,

Pages: 8    Published: Jan 1996

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Abstract

Single-fiber pull-out experiments under the microscope were compared with results from Instron pull-out experiments using the same glass fiber-room-temperature-cured epoxy system. It was found that when the loading system was stiff the pull-out curve obtained with the Instron had a transition which could be identified with the initiation of debonding, as seen under the microscope. Under these conditions debonding appeared to be a controlled fracture process. The work of fracture was about 70 ± 20 Jm^-2, and was governed by an equivalent debonding shear stress of 44 ± 8 MPa. The yielding process was initiated at a shear stress of 25 ± 6 MPa. These results could be obtained using a very simple analysis because they were not affected by friction.