Acoustic Emission Mechanism and Source Modeling of Dynamic Crack Detection in Steel Structure

Cracks are dangerous and frequently observed defects in steel structures. Therefore, the understanding of the mechanism of crack is very important to structure safety. Although the mechanism of static crack has been widely studied by researchers, the mechanism of dynamic crack has been left out and seldom been discussed. In this paper, a modeling method for acoustic emission (AE) source of dynamic crack was proposed for the mechanism revelation. In the method, AE signal was related to crack stress based on the theory of elasto-dynamics; the crack stress was inversely modeled from AE signal by employing half-space Green’s function and de-convolution procedure. When the method was applied to an AE testing for dynamic crack in steel structure, AE source function representing the time history of crack stress was obtained. The crack stress was found to be a step-like function with a pulse, and with it the mechanism and transient dynamic process of crack growth (crack initiation and propagation) was recovered. The results indicated that, the modeling method is effective for the study on the mechanism of dynamic crack. Copyright © 2013 IFSA.