RESUMO
Particulate polymer composites (PPCs) are widely applied under different elastic wave loading conditions in the automobile, aviation, and armor protection industries. This study investigates the elastic wave propagation behavior of a typical PPC, specifically a Cu/poly (methyl methacrylate) (PMMA) composite, with a wide range of particle contents (30-65 vol. %) and particle sizes (1-100 µm). The results demonstrate an inflection phenomenon in both the elastic wave velocity and attenuation coefficient with increasing volume content. In addition, the inflection point moves to the direction of low content with the increase in particle size. Notably, the elastic wave velocity, attenuation, and wavefront width significantly increased with the particle size. The inflection phenomenon of elastic wave propagation behavior in PPCs is demonstrated to have resulted from particle interaction using the classical scattering theory and finite element analysis. The particle interaction initially intensified and then reduced with increasing particle content. This study elucidates the underlying mechanism governing the elastic wave propagation behavior of high particle content PPCs and provides guidelines for the design and application of wave-absorbing composites.
RESUMO
The study of ultrasonic wave propagation is a crucial foundation for the application of ultrasonic testing in particle-reinforced composites. However, in the presence of the complex interaction among multiple particles, the wave characteristics are difficult to be analyzed and used for parametric inversion. Here we combine the finite element analysis and experimental measurement to investigate the ultrasonic wave propagation in Cu-W/SiC particle-reinforced composites. The experimental and simulation results are in good agreement and quantitatively correlate longitudinal wave velocity and attenuation coefficient with SiC content and ultrasonic frequency. The results show that the attenuation coefficient of ternary composites (Cu-W/SiC) is significantly larger than that of binary composites (Cu-W, Cu-SiC). This is explained by numerical simulation analysis via extracting the individual attenuation components and visualizing the interaction among multiple particles in a model of energy propagation. The interaction among particles competes with the particle independent scattering in particle-reinforced composites. SiC particles serve as energy transfer channels partially compensating for the loss of scattering attenuation caused by interaction among W particles, which further blocks the transmission of incident energy. The present work provides insight into the theoretical basis for ultrasonic testing in multiple-particle reinforced composites.