GUIDED-WAVES IN A JOINTED COMPOSITE PLATE

Reflection of guided waves by a thin region of bonding material at the interface between two composite plates has been investigated in this paper. The study is motivated by the need to develop a quantitative ul trasonic technique to characterize properties of joints between two pl ates, which may be laminated and anisotropic. Although there have been some recent studies that have examined the reflection and transmissio n of surface waves at the interface between two plates, they consider the two plates to be semi-infinite in thickness. Thus the mode convers ion of waves into higher guided modes of the plates are not taken into account. In this paper, a model study of the interaction of the Ao an d So guided wave modes with the joint material is presented. It is sho wn that as the frequency increases the coefficient of reflection shows resonant peaks at the cutoff frequencies of higher guided modes. Thes e peaks become increasingly pronounced as the thickness of the joint i ncreases. Another interesting feature is that the reflection coefficie nts have minima at a frequency that depends on the thickness and the p roperties of the joint material. These features can be used to determi ne the relevant properties of the joint.