Online Non Destructive Evaluation of Large Pipe Lines and Cylindrical Structures using Guided Ultrasonic Wave Diffraction Tomography
Sudhanshu Shekhar
Sudhanshu Shekhar, Ph. D. Scholar in Mechanical Engineering at Nims University, Shobha Nagar, Jaipur (Rajasthan), India.
Manuscript received on May 17, 2012. | Revised Manuscript received on June 22, 2012. | Manuscript published on June 30, 2012. | PP: 480-485 | Volume-1 Issue-5, June 2012. | Retrieval Number: E0518061512/2012©BEIESP
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Abstract: This Research work evaluates the ability of ultrasonic guided waves to detect several types of defects in cylindrical structures with different pre-selected wave modes. It will also demonstrate ultrasonic guided wave method [1& 2] as an alternative to standard ultrasonic techniques and how to address their deficiencies. This approach is based on the use of ultrasonic guided waves. In this work the use of ultrasonic guided waves for thickness mapping of large, partially accessible areas was investigated. The problem of interest is to evaluate the minimum remaining plate thickness over a large area. Guided waves [3 & 4] have multiple properties that can be used for thickness mapping over large areas. Firstly, the dispersive nature and variation of the phase velocity as a function of the frequency thickness product of guided waves [5 &6] make them potentially suitable for thickness mapping by time-of-flight tomography and diffraction tomography based on the variation of the velocity in the in homogeneities [7] .The experimental result was validated with FE (Finite Element) profile to arrive at the conclusion. Diffraction tomography can reconstruct a map of the velocity from the scattered field produced by the interaction of an incoming wave field and a velocity in homogeneity. It has been shown that Diffraction tomography with low frequency guided waves can be used for thickness reconstruction of plates or large diameter pipes. Low frequency guided waves can be used for thickness reconstruction of plates or large diameter pipes. It has been shown that the scattering from the array of transducers needs to be minimized in order to reconstruct thickness accurately. However when the scattering from the array of transducers is large it is possible to use guided wave diffraction tomography in a structural health monitoring approach and obtain accurate thickness reconstruction.
Keywords: Cylindrical Structures, Frequency.