- Volume 17 Issue 1
Ultrasonic tomography is a powerful tool for identifying defects within an object or structure. But practical application of ultrasonic tomography to solids is often limited by time consuming transducer coupling. Air-coupled ultrasonic measurements may eliminate the coupling problem and allow for more rapid data collection and tomographic image construction. This research aims to integrate recent developments in air-coupled ultrasonic measurements with current tomography reconstruction routines to improve testing capability. The goal is to identify low velocity inclusions (air-filled voids and notches) within solids using constructed velocity images. Finite element analysis is used to simulate the experiment in order to determine efficient data collection schemes. Comparable air-coupled ultrasonic signals are then collected through homogeneous and isotropic solid (PVC polymer) samples. Volumetric (void) and planar (notch) inclusions within the samples are identified in the constructed velocity tomograms for a variety of transducer configurations. Although there is some distortion of the inclusions, the experimentally obtained tomograms accurately indicate their size and location. Reconstruction error values, defined as misidentification of the inclusion size and position, were in the range of 1.5-1.7%. Part 2 of this paper set will describe the application of this imaging technique to concrete that contains inclusions.
- Cetrangolo, G.P. and Popovics, J.S. (2010), "Inspection of concrete using air-coupled ultrasonic pulse velocity", ACI Mater. J., 107(2), 155-163.
- Dhital, D. and Lee, J.R. (2012), "A fully non-contact ultrasonic propagation imaging system for closed surface crack evaluation", Exp. Mech., 52(8), 1111-1122. https://doi.org/10.1007/s11340-011-9567-z
- Gan, T.H., Hutchins, D.A. and Billson, D.R. (2002), "Preliminary studies of a novel air-coupled ultrasonic inspection system for food containers", J. Food Eng., 53(4), 315-323. https://doi.org/10.1016/S0260-8774(01)00172-8
- Hall, K.S. (2011), Air-coupled ultrasonic tomographic imaging of concrete elements, Ph.D. Dissertation, University of Illinois Urbana-Champaign, Urbana, Illinois.
- Ho, K.S., Billson, D.R. and Hutchins, D.A. (2007), "Inspection of drink cans using non-contact electromagnetic acoustic transducers", J. Food Eng., 80(2), 431-444. https://doi.org/10.1016/j.jfoodeng.2006.04.025
- Jackson, M.J. and Tweeton, D.R. (1994), Geophysical tomography using wavefront migration and fuzzy constraints, Technical Report 9497, U.S. Bureau of Mines.
- Koderu, J.P. and Rose, J.L. (2013), "Mode controlled guided wave tomography using annular array transducers for SHM of water loaded plate like structures", Smart Mater. Struct., 22, 125021. https://doi.org/10.1088/0964-1726/22/12/125021
- Naik, T.R., Malhotra, V.M. and Popovics, J.S. (2004), "The ultrasonic pulse velocity method", in CRC Handbook on Nondestructive Testing of Concrete, 2nd Ed., (Eds., V.M. Malhotra and N.J. Carino), CRC Press, Boca Raton, Chapter 8.
- Radon, J. (1917), "Uber die bestimmung von funktionnen durch ihre integralwerte lngs gewisser mannigfaltikeiten", Berichte uber die Verhandlungen der Sschsischen Akademie der Wissenschaften zu Leipzig, Mathematisch-Naturwissenschaftliche Klasse, 69, 262-277.
- Sanabria, S.J., Mueller, C., Neuenschwander, J., Niemz, P. and Sennhauser, U. (2011), "Air-coupled ultrasound as an accurate and reproducible method for bonding assessment of glued timber", Wood Sci. Technol., 45(4), 645-659. https://doi.org/10.1007/s00226-010-0357-z
- Wright, W.M.D., Hutchins, D.A., Gachagan, A. and Hayward, G. (1996), "Polymer composite material characterization using a laser/air-transducer system", Ultrasonics, 34(8), 825-833. https://doi.org/10.1016/S0041-624X(96)00083-2
- Abbaszadeh, J., Rahim, H.A., Rahim, R.A., Sarafi, S., Ayob, M.N. and Faramarzi, M. (2013), "Design procedure of ultrasonic tomography system with steel pipe conveyor", Sensor. Actuat. A - Phys., 203, 215-224. https://doi.org/10.1016/j.sna.2013.08.020
- Berriman, J., Purnell, P., Hutchins, D.A. and Neild., A. (2005), "Humidity and aggregate content correction factors for air-coupled ultrasonic evaluation of concrete", Ultrasonics, 43(4), 211-217. https://doi.org/10.1016/j.ultras.2004.07.003