| Summary: | 碩士 === 逢甲大學 === 機械工程學所 === 90 === Wave propagations in an inhomogeneous medium (e.g., particles, voids, defects, inclusions) undergo multiple scattering which results in a frequency dependent velocity and attenuation of coherent waves. The aim of this study is to analyses multiple scattering of plane compressional and shear waves in a composite containing randomly distributed spherical inhomogeneous inclusions or voids in a homogeneous isotropic medium. To calculate the effective wavenumbers of ultrasonic waves propagating in three types of heterogeneous materials, i.e., the particulate composites, porous materials and composites with multilayered interphases, a generalized self-consistent multiple scattering model is used in this study. Numerical results for the effective phase velocity and attenuation of both P and SV waves are calculated for a wide range of frequencies and concentrations. The proposed dynamic generalized self-consistent model for composites recovers both well-known static effective moduli ( Hashin (1962); Christensen and Lo (1979); Huang and Rokhlin (1996) ) in the static limit and the results at higher frequencies and concentrations agree well with published experimental data (Kinra and Rousseau, (1987) ).
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