A Study on Detection of Small Fault in Cast Thin Plate Using Hitting Sound

Abstract

The cast wood has the thin face with shallow grooves. The strength of the face was deteriorated, since the faults in the face cause the stress concentration. In order to investigate the possibility of the fault detection for the cast thin plate, seven kinds of thin plates with holes having a diameter of 0.3 to 1.0 mm and a depth of 0.7 mm were prepared and the hitting inspection were carried out using a swing robot. The signals were analyzed using FFT analysis and wavelet transform. The wavelet transform was better than the FFT analysis for the detection of the fault. It was possible to detect the existence of the fault in the plate using the hitting sound using the wavelet transform. It was clear that the fault detection in the thin plate depends on the relation between the vibration mode of the thin plate and the position of the fault in the plate.