Design and Implementation of a Fixed Distance to Object Imaging System using a 3-DOF. Table, with Integrated Software System for Acquisition, Processing and Display of Signals

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Karimi, Fateme | 2011

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 42008 (08)
University: Sharif University of Technology
Department: Mechanical Engineering
Advisor(s): Ravanbod, Hossein
Abstract:
Deriving the shape, area, volume, and orientation of a defect from the ultrasonic nondestructive testing images of the oil pipelines, paves the way for the estimation of its severity. This paper describes the design and implementation of an automatic structure which can move an ultrasonic probe over the surface of a test sample, while preserving the distance, i.e. stand-off, between them, whatever the shape of the surface might be. The fixed stand-off is implemented, closing a feedback loop with a distance meter sensor. Also an integrated software environment is developed for the control of the table, data acquisition, data processing and displaying the results. After acquiring the ultrasonic image, it is denoised using linear wavelet transform (WT). Then fuzzy thresholding is employed to estimate the area and volume of the defected region. The results show that ultrasonic imaging with fixed stand-off gives closer results to actual thickness than varying stand-off
Keywords:
Nondestructive Test ; Ultrasonic Imaging ; Scanner Table ; Thickness Measurement ; Stand-Off

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