Experimental investigation of ultrasonic attenuation behavior in carbon fiber reinforced epoxy composites

Ultrasonic attenuation in carbon fiber reinforced epoxy composites (CFRP) was studied experimentally. In this study, attenuation coefficients of longitudinal and transverse waves were measured by the spectral analysis of ultrasonic echoes obtained by aid of normal-incidence contact transducers. Measurements were carried out for epoxy resin and for unidirectional CFRP samples with different fiber volume fractions. For transverse waves, two polarization directions were examined which were parallel and perpendicular to the fiber direction. From these measurements, effects of the fiber volume fraction and the polarization direction on the ultrasonic attenuation behavior were investigated. Also, attenuation properties of CFRP laminates with different stacking sequences were measured and compared to those of unidirectional ones. Furthermore, the attenuation behavior was discussed in the light of a theoretical model for ultrasonic attenuation in unidirectional CFRP proposed by the authors.