Role of Roughness in Fibre/Matrix Interface Behaviour

摘要

Push-out and push-back tests are performed on monofilament model composites SiC/Pyrex, by using an indentation apparatus where the stiffness of the loading device can be changed. Under low stiffness, the sliding exhibits stick-slip motion and steady slip under high stiffness. During push-out/push-back cycling, the applied load decreases slowly indicating interfacial wear and progressive reduction of the effective interfacial shear stress. The radial clamping stress on the fibre is due to a combined effect of the thermal misfit and of an additional dilatancy coming from the crushing of the asperities. By push-back, the load-displacement curve exhibits a seating drop when the fibre reaches its original position again. Analysis of steady and serrated motion shows that the main interfacial wear occurs under low velocity sliding. Sliding velocity jumps indicate that the local contacts failures are creep controlled. All these features are described and discussed with regards to the physics of dry friction and micromechanics.