Wave Propagation In Particulate Composites Research Articles

U-DMA measurement and dynamic analysis of ultrasonic wave propagation in particulate composites

This work is dedicated to a high-precision ultrasonic testing technology for dynamic mechanical evaluation of particle reinforced composite materials. The detailed ultrasonic wave propagation due to multi-reflection and scattering waves by particles and matrix viscoelasticity, especially the mutual interactions among particles, are systematically clarified. Through a unique material evaluation method, Ultrasonic Dynamic Mechanical Analysis (U-DMA), the dynamic viscoelasticity of particulate composites with different types and contents of particles are measured directly in high frequency domain. Furthermore, based on the experiment data, the ultrasonic propagation behaviors are detailedly investigated by a newly developed time-domain finite element analysis code, Pzflex, for investigating the detailed mechanisms of particles. The results clarify that the particle interactions are playing a major role in ultrasonic wave propagation and attenuation properties, which can significantly affect the viscoelastic characteristics of developed particulate composite materials. And the feasibility and effectiveness of U-DMA are verified from both simulation and practical experiments.

Effect of Interface Anisotropy on Elastic Wave Propagation in Particulate Composites

ABSTRACTThe scattering of time harmonic plane longitudinal and transverse elastic waves in a composite consisting of randomly distributed identical isotropic spherical inclusions embedded in an isotropic matrix with anisotropic interface layers is examined. The interface region is modeled as a spherically isotropic shell of finite thickness with five independent elastic constants. The Frobenius power series solution method is utilized to deal with the interface anisotropy and the effect of random distribution of particulates in the composite medium is taken into account via a recently developed generalized self-consistent multiple scattering model. Numerical values of phase velocities and attenuations of coherent plane waves as well as the effective elastic constants are obtained for a moderately wide range of frequencies, particle concentrations, and interface anisotropies. The numerical results reveal the significant dependence of phase velocities and effective elastic constants on the interface properties. They show that interface anisotropy can moderately depress the effective phase velocities and the elastic moduli, but leave effective attenuation nearly unaffected, especially at low and intermediate frequencies. Limiting cases are considered and good agreements with recent solutions have been obtained.

A Dynamic Generalized Self-Consistent Model for Wave Propagation in Particulate Composites

Wave propagations in an inhomogeneous medium (e.g., voids, particles, defects, inclusions) undergo multiple scattering which results in a frequency-dependent velocity and attenuation of coherent wave. The aim of this study is to analyses multiple scattering of plane compressional and shear waves in a composite containing randomly distributed spherical inclusions in a homogenous isotropic medium. To calculate effective wave numbers of ultrasonic waves propagating in the heterogeneous material, 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 particulate composites recovers both well-known static effective moduli in the static limit and the results at higher frequencies and concentrations agree well with published experimental data.

A simple self-consistent analysis of wave propagation in particulate composites

A simple self-consistent embedding scheme is developed for the approximate analysis of waves in a composite consisting of a matrix containing inclusions. It employs an approximate solution for scattering from a single inclusion, which allows the development of simple explicit equations, comparable with those already known for elastostatics, which are easily solved by iteration. The performance of the scheme is discussed in relation to a variety of illustrative examples.