BEARING STRENGTH OF AS-CURED AND HYGROTHERMALLY CONDITIONED CARBON-FIBER EPOXY COMPOSITES UNDER STATIC AND DYNAMIC LOADING

Pin bearing behaviour of a range of laminate systems comprising unidirectional and woven carbon fibre-reinforced ordinary and toughened epoxy matrices were examined under static and dynamic loading. Static bearing properties were determined under various levels of bolt constraint with particular attention to onset of failure and failure modes. Load-amplitude controlled fatigue tests were conducted at 3 Hz, and to approximately 40% hole deformation which corresponds to the strains experienced at maximum static loads. Some test-pieces were hygrothermally conditioned at 56-degrees-C and 95% relative humidity. The properties depended mainly on the laminate type, ply stacking sequence and specimen geometry. The definition of strength as in ASTM D953-87 was found to have no bearing on the material integrity. However, strength at failure initiation under static loading was found to have greater significance, particularly in relation to fatigue behaviour.