Acoustic Wave Reflection from Water/Laminated Composite Interfaces

The high specific strength and stiffness of composite materials has led to their widespread use in efficient structures. Since most of these structures are subjected to cyclic loads which can lead to rapid degradation in load carrying capability, initial inspection and continued monitoring of these materials for detection and sizing of strength degrading flaws is necessary in order to ensure adequate structural reliability. Unfortunately, many of the current inspection techniques can not be directly utilized for this purpose because of the inhomogeneous, anisotropic nature of composites. In addition, the types and numbers of internal flaws that must be detected and quantified for structural integrity models differ substantially from those traditionally encountered. Currently the most useful technique for inspecting composite structures is ultrasonic c-scanning which was developed to inspect homogeneous, isotropic materials, i. e., metals. Before this technique can be fully exploited for inspecting composites, a firm understanding of the interaction between ultrasonic waves and the material is necessary