Search Results

You are looking at 1 - 2 of 2 items for

  • Author: Dibya Jena x
Clear All Modify Search
Open access

Dibya Jena and Rajesh Kumar

Implementation of Wavelet Denoising and Image Morphology on Welding Image for Estimating HAZ and Welding Defects Dibya

In the current work, a filtering scheme for measurement of area and perimeter of heat affected zone (HAZ) in welding has been proposed along with identification of defects like porosity in the fusion zone. A filtering scheme based on wavelet filtering, edge detection and morphology has been designed and implemented on a welding image for this purpose. To see the effectiveness of the wavelet based proposed filtering scheme, SNR is calculated and compared with the filtered image processed without wavelet denoising. Experimental results revel that the SNR improves by 45-65% when wavelet filtering is introduced in the filtering scheme. Crisscrosses of the boundary of HAZ were observed and compared. The wavelet based proposed filtering scheme enhances the HAZ boundary smoothness by 12.5% in comparison to the filtering scheme without using wavelet denoising. In the limiting case, for poor quality image of weldment, the deviation in measurement of HAZ by manual and proposed scheme is within 10%. Error in manual evaluation significantly contributes in the above deviation as the HAZ on the base metal side in the raw image is diffused and difficult to measure accurately.

Open access

Dibya Jena, Manpreet Singh and Rajesh Kumar

Radial Ball Bearing Inner Race Defect Width Measurement using Analytical Wavelet Transform of Acoustic and Vibration Signal

In the present work, an experiment is carried out with a customized test setup where the seeded defects are introduced in the form of an axial groove on the inner race of a radial ball bearing. The nature of the acoustic and vibration signal bursts, and their correlation with the inner race defects, are established and estimated. Experimental investigation reveals that the analytical wavelet transform (AWT) is an effective tool for analyzing the acoustic and vibration signals, transmitted from the bearing, in order to characterize and measure the defect size. In the recent work, AWT followed by the time marginal integration (TMI) have been implemented on acoustic and vibration signals of a defective radial bearing. Size of the defect in the inner race of bearing is corroborated well with AWT scalogram. The segregation of the defect is carried out on TMI graph across the highest amplitude spike, which is due to signal burst (due to a contact of ball with bearing inner race defect). This manual demarcation on TMI graph in time axis provides the time duration (contact between a ball and the inner race defect). Using this time duration of the ball passed over bearing inner race defect, RPM of shaft mounted across bearing, and the fundamental train frequency, the defect width is estimated. The deviation of the measured width from the actual, using the proposed method, is sought below 5%. Summarizing, the proposed method can be reckoned a suitable and reliable measurement of radial bearing inner race defect width from acoustic and vibration signal.