A Detection Method for Metal Plate Surface Defects Based on an Array Flat Plates Capacitive Sensor

To effectively identify and locate the surface defects of the metal plates, this research proposed a detection method based on an array flat plates capacitive sensor. To study the electric field distributions of the surface defect on metal plates and the potential difference of the induction electrode pairs, a mathematical model used to detect the surface defects of the metal plates was established in COMSOL. Based on the established model, the parameters of the PCB sensor layout were optimized, and the impact factors of the defect detection were studied. To accurately identify and locate the position of the defects, three-dimensional and two-dimensional images were made using the measured data of six different defect shapes. To verify the effectiveness of the proposed method, a non-destructive testing platform including eight-channel capacitor electrodes on PCB signal condition circuit and sampling system was developed. Experimental results demonstrate that the proposed method can rapidly, conveniently and effectively detect and locate surface defects on metal plates.