Acoustic-Emission Criteria for Rapid Analysis of Internal Defects in Composite Materials

We present the results of acoustic-emission investigation of volume damage of composite materials with various types of stacking of carbon fibers. All 16 layers of fibers placed in the same matrix give different contributions to the strength properties of the material with varying acoustic-emission activity in the process of loading. We established criteria for the quantitative estimation of volume damage of composite materials with regard for the specific character of changes in amplitudes of acoustic-emission signals at various stages of loading. The analysis of spectral characteristics of acoustic-emission pulses passed through original and damaged materials of the specimen confirms the efficiency of the proposed criteria. We give values of criterional parameters for the investigated types of specimens of composite materials.