International Journal of Applied Electromagnetics and Mechanics 55 (2017) 257–269 257 DOI 10.3233/JAE-170066 IOS Press A numerical study on eddy current signal characteristics of imitative stress corrosion cracks Cherdpong Jomdecha a , Wenlu Cai a , Shejuan Xie a , Zhenmao Chen a,∗ and Peng Li b a Shaanxi Engineering Research Center for NDT and Structural Integrity Evaluation, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China b Xinjiang Inspection Institute of Special Equipment, Urumqi 830011, Xinjiang, China Abstract. This paper presents numerical simulation results of eddy current signals to determine the appropriated dimensions of imitative stress-corrosion cracks (SCCs) in viewpoint of similar eddy current testing signals. The imitative SCCs were modelled as multiple tiny slits in three dimensions. A Finite Element and Boundary Element hybrid method (FEM-BEM) was utilized to simulate the eddy current signals in an impedance form of an absolute pancake coil. Equivalent conductivity (σE) of the imitative SCCs was estimated by using a uniform notch model at a fixed width of 0.2 mm, and adjusting the conductivity in the notch region. According to the numerical results, the impedance amplitude could be significantly used to quantify the σE of imitative SCCs. In addition, the variation of test frequency affecting to σE value was investigated. Finally, the appropriated imitative SCCs dimensions for the eddy current testing were quantitatively predicted by using a statistical methodology. Keywords: Stress corrosion cracks, imitative SCC, eddy current testing, FEM-BEM 1. Introduction Stress corrosion crack (SCC) is an essential service failure in engineering materials of the components and structures. The SCC occurs by environmentally induced crack propagation [1–3]. It can form as only a single crack or a group of colonies depended on many factors such as material, shape, type of stress, pH environment and type of corrosion. Evaluation of SCC by using the eddy current testing (ECT) is an important issue in nuclear power plants, petrochemical and aerospace industries [4–6]. Although the ECT has high performance to treat the surface breaking SCC in length, it is still difficult to quantify the actual profiles with the measured signals. At the presents, SCCs have been researched and simulated to be conductive cracks in the view- point of ECT. There were some reports to explore the equivalent conductivity inside the SCC regions by numerical simulation of the uniform conductive cracks [7–9]. The results indicated that there was no correlation between conductivity and SCC width, but the SCC size related to its equivalent electrical * Corresponding author: Zhenmao Chen, Shaanxi Engineering Research Center of NDT and Structural Integrity Evaluation, State Key Laboratory for Strength and Vibration of Mechanical Structures, Xi’an Jiaotong University, Xi’an 710049, Shaanxi, China. E-mail: chenzm@mail.xjtu.edu.cn. 1383-5416/17/$35.00 c  2017 – IOS Press and the authors. All rights reserved