Propagation of the Fundamental Symmetric Lamb Mode in a Symmetrically Delaminated Composite Laminate

Abstract

In this paper, a study on the propagation of the fundamental symmetric Lamb mode (So) in a symmetrically delaminated glass/epoxy composite laminate is presented. It was found that when So mode is incident at the front and rear edges of a symmetric delamination, it generates Ao mode. This mode is exclusively confined to the sub-laminates. It was also observed that, during the interaction of the generated Ao mode with the edges of delamination, it, in turn generates So mode. Thus, So mode and mode converted Lamb modes undergo multiple mode conversions in the sub-laminates. The only mode that propagates in the main laminate is So. A signal-processing scheme based on the time-frequency spectrographic analysis was utilized to identify the wave groups propagating in the main and sub-laminates.