EQUIVALENT ULTRASONIC IMPEDANCE IN MULTILAYER MEDIA. A PARAMETER ESTIMATION PROBLEM

M.G. MESSINEO; G.L. FRONTINI; G.E. ELICABE; LUIS GAETE GARRETON

Joao Pessoa

Simposio; Inverse Problem Design and Optimization Symposium; 2010

UFPB - UFRJ Brasil

This article deals with ultrasonic transmission through multilayer systems. We consider the equivalent ultrasonic impedance of such systems as a convenient model to reduce the computational time for numerical evaluation. We also use the one dimensional wave equation as the appropriate model for the propagation of a plane wave inside the material. From numerical simulation, we obtain and register signals useful to validate the equivalent model. Results clearly depict coherence between the models since there are full agreement in the computed velocity and stress applied to each layer. The identification of the parameters involved in the model, layers densities and propagation velocities, may be formulated as an inverse problem of non linear parameter estimation. The minimization of a least squares objective function is necessary for the estimation of the parameters, which are related to the material elastic constants, important properties for the mechanical characterization of the sample.