Nonlinear Propagation of Amplitude-Modulated Ultrasonic Wave in Composite Material

摘要

Some nonlinear effects in the ultrasonic wave propagation in a unidirectional carbon/carbon (C/C) composite were examined experimentally. High-power amplitude-modulated longitudinal ultrasonic waves were sent to the C/C composite sample, and the nonlinear generation of low-frequency components was observed. Due to the heterogeneity and pre-existing damage of the composite, the carrier-wave component undergoes severe attenuation, and the low-frequency components were dominant in some situations. Such low-frequency components are found to grow in a nonlinear manner, and can be a useful source of information characterizing the nonlinearity of the material.