Elastic Properties Inversion of an Isotropic Plate by Hybrid Particle Swarm-Based-Simulated Annealing Optimization Technique from Leaky Lamb Wave Measurements Using Acoustic Microscopy

Abstract

This paper presents a new method for the inversion of elastic properties of an isotropic thin plate by line-focus acoustic microscopy. Over 10 modes of the leaky Lamb waves of a 380 \(\upmu \)m thick aluminum plate were extracted by the \(V(f\),\(z)\) measurement. The inversion method of hybrid particle swarm-based-simulated annealing (PS-B-SA) optimization induces an objective function dependent on the determinant of the coefficient matrix of the dispersive characteristic equation. PS-B-SA allows considerable flexibility in parametric inversion problem and seeks the global rather than the local minimum. An alternative image display method combined with the objective function will be used to show the dispersion curves and to demonstrate the principles of the PS-B-SA optimization algorithm. The elastic properties (Young’s modulus \(E\), shear modulus \(G\), Poisson’s ratio \(\nu \)) and thickness (2\(h)\) of the specimen are determined by the inversion of the dispersion curves. Inversed parameters by particle swarm optimization algorithm are compared with the PS-B-SA results to show the validity and stability of the hybrid method. Agreement between the inversed material parameters and the reported data is shown to be excellent.