Regulating crack propagation in laminated metal matrix composites through architectural control

Abstract

To regulate the bending behavior of laminated metal matrix composites, the effects of stacking sequence and notch position were studied by using both numerical simulation and experimental testing. Laminated composites consisting of TiB/Ti6Al4V composite layer and Ti6Al4V ductile layer were fabricated. The results of numerical simulation on specimen with alloy layer as the outermost layer indicate a better bending ductility compared with the other stacking sequence, and this conjecture was also confirmed by the experimental result where a double increase in bending strain was observed. This was attributed to the tunneling crack blunting by adjacent alloy layers. As for the notch position, crack was preferentially to generate in the composite layer first whether the pre-notch existed in alloy layer or in composite layer. If pre-notched on the alloy layer, tunneling crack in the composite layer would extend earlier than the fracture of the notched outermost layer. For specimen with pre-notch in the composite layer, the adjacent alloy layer and the inner composite layer would fracture at the same time after the crack initiation of the notched composite layer. The fracture behavior of laminated composites can be manipulated by conveniently tailoring stacking sequences and notch position.