Interaction of guided Lamb waves with an asymmetrically located delamination in a laminated composite plate

Propagation of the primary anti-symmetric Lamb mode (A(o)) in an asymmetrically delaminated cross-ply laminate has been studied through both numerical simulations and experiments employing the air coupled ultrasonic technique. When the A(o) mode interacts with the entrance and the exit of an asymmetrically located delamination, in addition to A(o), a mode converted to the primary symmetric Lamb mode (S-o) also propagates in each of the two sub-laminates as well as the main laminate. These Lamb modes propagate independently in each of the sub-laminates. In addition, turning modes (i.e. the mode propagating in one sub-laminate interacts with delamination edge and starts propagating in the other sub-laminate) and a mode converted turning mode (a new mode is generated during the interaction of turning mode with delamination edge) were also observed in the numerical simulation. The presence of the 'mode converted turning modes' was also validated through the experiments in this study.