Application of an inverse method for determination of elastomeric material properties from acoustical test data

The work described in this study develops an inverse method designed to obtain the complex dilatational and complex shear wavespeeds of a material from physical test data. The inverse method is devised from a recently established forward model that explicitly predicts the echo reduction and insertion loss of a material at any wavenumber and frequency given the correct material properties. The forward model has closed-form equations that completely describe the system physics of a submerged material. The inverse method incorporates this model and physical test data into a Newton-Raphson iteration to obtain the complex dilatational and complex shear wavespeeds of a material. The complex wavespeeds are then used to obtain the material Lame constants. The inverse method developed provides the critical link needed between the test data and analytical modeling.