An Approach to Guided Wave Mode Selection for Inspection of Laminated Plate

Abstract

Overall philosophy of composite material inspection is discussed with a sample problem presentation to illustrate the utility of guided wave analysis and the use of field distributions across the thickness of a specimen to predict its sensitivity to specific anomalies in the material. Guided Lamb-type waves in a three-layered laminated compos ite plate with different anomaly content is studied in this article. Our work is focused pri marily on the detection of interlaminar bond layer imperfections and cracks normal to the interfaces. A Lamb wave mode selection criteria is discussed with respect to defect sen sitivity analysis. Selection of appropriate modes and frequencies is suggested by an ap proach based on an analysis of the modal displacement and power distribution across the multilayered structure as opposed to the previously utilized approach based on a numerical analysis of the dispersion relations for different boundary conditions and effective material properties.