RELATIONSHIP BETWEEN ACOUSTIC-EMISSION AND DEVELOPMENT OF THE DAMAGE ZONE IN THE INTERLAMINAR FRACTURE OF FIBER COMPOSITES

A study is made of unidirectional carbon-fiber-reinforced composites w ith both thermosetting and thermoplastic matrices. Experimental data o n acoustic emission for unidirectional fiber composites with a crack i s presented in the form of an exponential dependence of the number of AE signals on the stress-intensity factor. The increase in the size of the damage zone across the layers of the composite turns out to be li nearly dependent on loading rime (and, thus, on K-1c) in contrast to t he usual quadratic dependence along the layers.