Stress redistribution around mechanical attachments in ceramic matrix composites

The load-bearing capacity of mechanical attachments for ceramic matrix composite (CMC) components is investigated, by using the pin-loaded sub-element. The emphasis is on the role of stress redistribution mechanisms. It is found that for a 0/90, SiC/calcium aluminosilicate composite, the inelastic strains are sufficient to eliminate stress concentrations around the hole, in all loading conditions. In consequence, it has been possible to specify a failure mode map plus actual failure loads, in terms of the ultimate strengths of the composite measured in tension, shear and compression. The crucial role of stress redistribution by matrix cracking (with interface debonding and sliding) in imparting excellent structural performance to CMCs is highlighted.