J042014 Development of the theory of nonlinear resonant ultrasound spectroscopy (NRUS)

Abstract

Free-vibration acoustic resonance of a two-dimensional St.Venant-Kirchhoff hyperelastic material was investigated within a framework of the calculus of variation. Displacement functions in the medium are expanded by the complex Fourier series up to the order of ±2 in time and 4 in space: consequently, the degree of freedom of the basis function is 64. Numerical analysis based on the Ritz method revealed that resonance frequency of the medium decreases monotonically with increasing in the vibration amplitude. Nonlinear excitation of high wavenumber modes has also been confirmed.