Inversion of Functional Graded Materials Elastic Properties from Ultrasonic Lamb Wave Phase Velocity Data Using Genetic Algorithm

An inverse method based on genetic algorithm (GA) is presented to determine the elastic properties of functional graded materials (FGMs) plate from lamb wave phase velocity data. The Legendre polynomial expansion method is used as a forward solver to calculate the phase velocity dispersion curves of lamb wave in FGMs plate, which has a distribution function to express the inhomogeneity of materials’ elastic properties. The properties of FGMs plate can be characterized by minimizing the standard deviations between the actual and calculated phase velocities of lamb waves. By using GA, the elastic parameters of FGMs plates with three different distribution functions are inversed, and the convergence and deviations of the inversion are also discussed. The investigation shows that this inverse method is efficient and accurate for determining the materials parameters of FGMs and the deviation can be controlled below 5 %.