Study on a combined NDT method based on ACFM and eddy current thermography

ABSTRACT

Alternating current field measurement (ACFM) and eddy current thermography are two non-destructive testing (NDT) methods widely used in industries. In this study, a combined NDT method based on the two methods is proposed. Firstly, some relative mathematical models are provided, and then an experimental system is designed for the combination of the two methods. The obtained magnetic field signal is smoothed by the double moving average method and crack identification and location are realised by using the method based on the morphological characteristics of Bx curve. Then, the thermal images are processed by a new method which is called virtual sensing technology (VST). It proves that VST can extract useful defect information from the images efficiently. The effect of excitation current on magnetic field and temperature field is studied and optimal current value is determined. Also, the effect of temperature and external magnetic field on magnetic field sensor is discussed. Finally, the future prospects of the combination of ACFM and eddy current thermography are discussed in this paper.

KEYWORDS:

• A combined method
• NDT
• ACFM
• Eddy current thermography

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the program of Natural Science Foundation of Shandong Province [ZR201807080173], National Natural Science Foundation of China [Grant No. 51474138], Scientific Research Foundation of Shandong University of Science and Technology for Recruited Talents [2017RCJJ002], First-class Discipline of Mineral Engineering construction project of Shandong University of Science and Technology [Grant No. 01AQ01805], Natural Science Foundation of Shandong Province [ZR2018BEE003], and State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology.