INTERLAMINAR SHEAR STRENGTH OF CERAMIC COMPOSITES BY ASYMMETRICAL FOUR POINT BEND SHEAR TEST

摘要

Strength and failure of continuous fiber reinforced composites strongly depend on loading direction with respect to their principal material axes. The interlaminar shear strength, under study here, could be measured by several methods, including short-beam, Iosipescu, double-notch shear (1). Ideally, the shear test method used is desired to provide a pure shear distribution. This is not always possible due to the limited availability of specimen and test methods; thus, the alternative testing methods are needed. The interlaminar shear strength was measured by the asymmetrical four-point bend (AFPB) shear test, which was originally introduced by Slepetz et al. (2). Although the AFPB test provides a nearly pure shear stress state with an unnotched specimen, it has not found a wide acceptance partly because (a) the dependence of the stresses on the span dimensions could lead to premature failure in brittle materials (3), and (b) due to the occurrence of excessive bending in the ductile materials (4). Our work with the AFPB test method showed that under proper care the success rate could be improved, particularly for the monolithic ceramics (3,4). The goal of this investigation is to demonstrate further use and application of this test method to measure the interlaminar shear strength of composites.