Revealing the high-frequency attenuation mechanism of polyurea-matrix composites

In this paper, a method for analyzing the high-frequency attenuation property of polyurea-matrix composites is developed by combining experimental, computational and theoretical approaches. First, the ultrasonic experimental platform is established by solving the difficulties of high-frequency ultrasonic testing as high-frequency signal distortion, insufficient driving voltage and sampling rate failure, to study the dynamic mechanical properties (1–5 MHz) of pure polyurea and polyurea-matrix composites. Then, the influences of composite parameters including the size and volume fraction of inclusions on wave attenuation performance under different frequencies are obtained and further verified by numerical simulations. Next, the contribution of inclusions to the wave attenuation performance is also theoretically analyzed. It is found that the increase of inclusion volume fraction and inclusion diameter will increase the attenuation coefficient of the composites. And the attenuation of composites with the inclusions of a 150-μm diameter and 30% as volume fraction can be 82% higher than pure matrix. This amplifying attenuation effect of inclusions is mainly attributed to the scattering effect, which is verified by comparing numerical and theoretical results.