Effect of propagation distance on acoustic emission of carbon fiber/epoxy composites

This study examined the change in acoustic emission as a function of measurement position of fiber-reinforced composites. Single-edge-notched carbon fiber/epoxy composites were prepared and tested under cyclic loading, with sensors located at specific distances from the end of the notch. Although the Ib-value increased overall, the degree of increase significantly varied with position and acoustic emission frequency. Notably, the proportion of acoustic emission signals for each failure mode varied due to a high attenuation rate at high frequencies, which increased the Ib-value. Accordingly, the high-frequency fiber-failure signals significantly affected the Ib-value. This study focused on the importance of analyzing acoustic emission signals by considering the crack location and frequency-dependent attenuation rate. We concluded that an acoustic emission sensor should be located 20–40 mm from the crack location for woven carbon fiber/epoxy composites.