7 ACOUSTIC EMISSION DETECTION IN CONCRETE SPECIMENS: EXPERIMENTAL ANALYSIS AND SIMULATIONS BY A LATTICE MODEL

In civil engineering, materials subjected to stress or strain states a quantitative evaluation of damage is of great importance due to the critical character of this phenomena, which at certain point suddenly turns into catastrophic failure. An effective damage assessment criterion is represented by the statistical analysis of the Acoustic Emission (AE) amplitude distribution signals that emerges from the growing micro-cracks. The amplitudes of such signals are distributed according to the Gutenberg- Ritcher (GR) law and characterized through the b-value which systematically decreases with damage growth. The b-value analysis was conducted on two experimental tests carried out on concrete specimens loaded up to failure. The first one is a prismatic specimen subjected to uniaxial compression load, the second one is a pre-cracked beam subjected to three point bending test. The truss-like Discrete Element Method (DEM) was used to made numerical simulation on the experimental tests. The comparison between experimental and numerical analyses, in terms of load vs. time diagram and AE data, elaborated throughout the b-value and signals frequencies variations, provided results in good agreement