Analysis of acoustic emission signal characteristics based on the crack pattern of stress corrosion cracking

Abstract

The problem of stress corrosion cracking (SCC), which causes sudden failure of metals subjected to stress in the high-temperature, high-pressure water environment. Fortunately, acoustic emission (AE) monitoring technique shows a promising method for detecting the initiation and propagation of SCC. In this study, a simplified fracture propagation model of type 316LN stainless steel is established based on the moment tensor theory, the inner connection between the energy release rate of AE source and morphological aspect of crack formation is analyzed. Based on the nonlinear finite element method (FEM), The AE waveform data from the crack formation of various depths are obtained, and the energy release rates from various AE sources are analyzed. The results of modal analysis show that energy released by the growing crack is linearly proportional to crack depth. Moreover, their frequency characteristics are almost unchanged from analysis results by fast Fourier transform (FFT). Therefore, SCC initiation and propagation can be evaluated based on this detection method. And, the appropriate AE sensors and detection systems have the potential to achieve remote real-time monitor of initiation and propagation of SCC. This analysis method can also extended to almost all solid materials and structural crack detection.