An Acentric Archimedes Spiral Coil For Inspection of an Aluminium Plate with an Inhomogeneous Thickness

作者：Z. Cai, Zhengshi Lu, Yibo Li, Yihu Sun, Qixiang Zhao · 发表于：Nondestructive Testing and Evaluation · 年份：2023 · DOI：10.1080/10589759.2023.2183954 · 被引用次数：3

ABSTRACT Electromagnetic acoustic resonance (EMAR) technology has potential to improve signal-to-noise ratio (SNR) and reduce noise effects in metal plate thickness measurement. However, using traditional EMAR to detect inhomogeneous-thickness specimens can result in difficulties accurately determining thickness and identifying interfaces due to multiple resonant frequencies. This paper proposes a signal processing method called frequency-frequency energy density separation (FFEDS) to obtain the energy density ratio (EDR) for different thicknesses using EMAR. A new coil structure, the Acentric Archimedes Spiral Coil (A-AS-Coil), and two scanning schemes (transverse and rotational) are designed. Experimentally, transverse scanning with the A-AS-Coil shows a nonlinear change in EDR, improving sensitivity in identifying interfaces. Rotational scanning with the A-AS-Coil increases the change in EDR by 106.2%, different from the conventional spiral coil.