The effect of residual stresses and sample preparation on progressive debonding during the fiber push-out test

Iterative finite-element analyses have been conducted to determine the debo nd length as a function of force during progressive debonding in fiber push -out tests. This procedure was applied to data from push-out tests on a ste el/ epoxy model composite. During push-out testing this composite debonded from the bottom (support) face of the sample. The modeling allowed debondin g from the bottom and included pre-existing debonds caused by resisdual str esses and/or sample preparation. The predicted debond lengths were within 1 0% of the measured debond lengths. Evidence is also shown that cutting and polishing can cause debonds that are longer than one third of the sample th ickness in samples with a relatively small diameter steel fiber. (C) 1998 E lsevier Science Ltd. All rights reserved.