An Inverse Modeling Method for Acoustic Emission Source of Cracking

Abstract

Crack formation is a severe problem concerning steel structures under service loading. Understanding of the mechanism of crack initiation and propagation is therefore critical to structure safety design and maintenance. Although many efforts were put into crack mechanism studying, and some progress has been made in the aspect of crack propagation, the problem of crack initiation i.e. cracking remains left unsolved. In this paper, an inverse modeling method for acoustic emission (AE) source of cracking 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 half-space Greens function and procedure of de-convolution. In an application to the AE testing for steel structure cracking, 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 of cracking was recovered. The results indicated that, the modeling method is effective for the study on mechanism of cracking.