Modeling the Propagation of Ultrasonic Guided Waves in Four-Layer Laminated Composites

Graphite-epoxy composites are widely used in the space industry. They have the advantage of being resistant to thermal distortion with high structural rigidity and minimal weight. However, the non-complete adhesion between fiber and matrix and the defects resulting from the manufacturing processes can affect these structures. It seems therefore necessary to control these materials. The non-destructive testing by ultrasonic guided waves presents an interesting alternative for the detection of these imperfections. For a proper ultrasonic non-destructive testing by guided waves, the knowledge of dispersion curves is an essential step to determine the modes susceptible to propagate in our material during the control. In this paper, we present analytical matrix methods for plotting the dispersion curves of a graphite-epoxy laminate composite material. The formulations and limitations of these methods have been presented. We have modeled the propagation of ultrasonic guided waves in two- and four-layer anisotropic laminates for different fiber orientations. The accuracy of the obtained results has been checked with the help of the software DISPERSION CALCULATOR.