Showing papers by "Zheng Fan published in 2006"
Journal Article•
TL;DR: In this article, an approach based on the concept of equivalent nonlinear parameter is presented to estimate the linear and nonlinear properties of porous rubber-like medium with particular interest on the nonlinearity caused by nonlinear oscillation of the micropores.
Abstract: A high value of nonlinearity has been found in a class of rubberlike medium containing micropores. Under external ultrasonic excitation, the micropores display nonlinear oscillation due to the weak compressibility of the rubberlike medium. An approach based on the concept of equivalent nonlinear parameter is presented to estimate the linear and nonlinear properties of porous rubberlike medium with particular interest on the nonlinearity caused by the nonlinear oscillation of the micropores. The porous rubberlike medium is considered as a homogenous medium with an equivalent nonlinear parameter. The frequency dependence of the equivalent nonlinear parameter is studied and its characteristics are associated with the scattering fields of the individual pore. At low frequency range, the presented equivalent nonlinear parameter can also well predict the nonlinearity mainly caused by the microstructure of the porous medium, which is consistent with L. A. Ostrovsky's static results [1]. The results of fundamental frequency field are compared to G.C.Gaunaurd's work [2], showing good agreement, which provides further justification for our method. The effects of size distribution of pores on the fundamental and second harmonic fields are also examined.
1 citations
TL;DR: Theoretical comparisons of mathematical formulations and intrinsic relations between these two approaches are given and show their consistency in dealing with the linear acoustics in bubbly liquids.
12 Jun 2006
TL;DR: In this article, an approach based on the equivalent medium method is used to describe the propagation of acoustic longitudinal wave in porous viscoelastic medium, combining the wave equation for the porous medium and the dynamic equation for micropores.
Abstract: An approach based on the equivalent medium method is used to describe the propagation of acoustic longitudinal wave in porous viscoelastic medium. Combining the wave equation for the porous medium and the dynamic equation for micropores and using the perturbation method, equations for fundamental and second harmonic are obtained. Treating medium containing micropores as a homogeneous medium, the effective nonlinearity parameter is defined, and a formula for it is achieved. The frequency dependence of effective nonlinear parameter is studied in detail, and its low frequency limit consists with Ostrovsky’s static results.