Material characterization of FGM plates using elastic waves and an inverseprocedure

A computational inverse procedure is presented for characterization of the material properties of functionally graded materials (FGMs) using the surfa ce displacement response of the plate. A modified hybrid numerical method i s first developed combining some existing techniques to compute the wave fi eld in an FGM plate for given material properties and their variation in th e thickness direction. The modified HNM allows a linear variation of materi al properties in the element in the thickness direction. This is to reduce the number of elements needed to model the material variation of FGM. The m odified HNM is proven more efficient than the original HNM. The high effici ency paves the way for inverse procedure. The reconstruction of the materia l properties of FGM plates is performed using an inverse procedure of nonli near least squares method. Numerical examples are presented to demonstrate the present procedure for material characterization of FGM plates. The pres ent procedure can recover accurately the material properties of an FGM with an initial guess of up to 40% off from their true values.