THE RELATIVE RESIDUAL FIBER DISPLACEMENT AFTER INDENTATION LOADING AND UNLOADING OF FIBER-REINFORCED CERAMIC COMPOSITES

The interfacial properties of fibre-reinforced ceramic composites have been evaluated by using the indentation technique. The ratio of the r esidual fibre displacement after complete unloading to the fibre displ acement at peak loading is examined. Assuming a constant interfacial s hear stress at an unbonded interface, this ratio is 0.5. However, devi ation of this ratio from 0.5 is always obtained from experimental resu lts. Both Poisson's effect and the existence of the residual axial str ess have been proposed to explain this deviation. A methodology is pre sented in this study to classify conditions for which either Poisson's effect or the residual axial stress dominates this deviation. The app lication of this methodology to Nicalon fibre-reinforced lithium alumi nosilicate glass-ceramic is also illustrated.