抄録
Attenuation characteristics of ultrasonic transverse waves in unidirectional carbon fiber-reinforced plastics are examined based on a theoretical model recently put forward by the authors. The model accounts for energy losses due to wave scattering by the fibers as well as viscous absorption in the matrix, and gives the composite attenuation coefficient as a function of frequency. In the present study, two modes of ultrasonic transverse waves, i.e. with polarization direction normal and parallel to the fiber direction, are considered for the common propagation direction normal to the fibers. Moreover, the model is extended to deal with composites with highly concentrated fibers using a differential scheme. Based on the results of the numerical analysis, attenuation behaviors of the two transverse wave modes are discussed in detail. The results show that the attenuation coefficients of the composite are smaller than that of the epoxy matrix, for a frequency range relevant to practical situations. Furthermore, attenuation in CFRP is more pronounced in the case when it is polarized parallel to the fibers than in the case when it is polarized perpendicularly. Attenuation characteristics of transverse waves in CFRP are also compared to those of the longitudinal wave analyzed previously.
