Single-ply elastic properties determination in CFRP laminates using a combined ultrasonic method

Estimation of the elastic properties in composite laminates is very important. Researchers usually consider the laminate as a whole and identify its equivalent stiffness properties. However, determining the elastic properties of each layer within a laminate can provide more comprehensive information to the users. In this paper, an ultrasonic method is proposed to reconstruct the single-ply elastic properties by combing bulk and guided waves. Herein, a novel double-side-transmitted bulk wave method is developed to identify the stacking sequences, providing the necessary information for further evaluation of the single-ply elastic properties. The double-side-transmitted bulk wave method is demonstrated under various layup scenarios, allowing the detection of more layers than conventional techniques. The laser-generated guided wave velocities are then inverted by genetic algorithms (GAs) to reconstruct the single-ply elastic properties. An effective indicator, the coefficient of variation, is designed to represent the accuracy of the identified single-ply material properties. And the experimental dispersion curves are in good agreement with the theoretical dispersion curves under the identified material properties.