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Rockbolter is the name I gave to the ultrasonic apparatus I designed for my PhD project in the Mining Department , Nottingham University, England, from 1985 to 1988. It was the subject of a patent application No8802105 which was published on 13 September 1989.
A full article about the device and the method used for testing material samples was published in the Journal of the British Institute of Non-Destructive Testing, INSIGHT, Vol. 38 No 10. on 10 October 1996, under the title: A Mode-Conversion Method for Evaluating Elastic Properties of Materials.
ABSTRACT
An ultrasonic apparatus for evaluating elastic moduli of materials was designed. The problem of measuring shear-wave velocity, which could be difficult to overcome with equipment using shear-wave transducers, was solved by a transducer-cell. In this latter, only a compressional wave transducer was used. The specimen is in the form of a prism and the angle arrangement of the specimen and the transducer allowed compressional waves to be refracted either as compressional or shear waves depending on the angle of incidence of the sound beam on the liquid-solid interface. Thus, both velocities could be computed in a relatively simple manner with the help of a special formula, which contains only easily measured variables. The device can be used with existing flaw detectors which are based on transit-time measurement of a pulse-echo. It could also be linked to a computer through a computer interface in order to make a semi-automated system for computing and displaying elastic constants of materials.
The author used no off-the-shelf equipment: in addition to the transducer-cell, which is the subject of this paper, he designed a transducer holder, a power amplifier, a frequency synthesizer, a computer interface, and a computer program in order to control the whole experiment.
The whole apparatus, from left to right, the BBC computer, the rack system which houses the electronic modules, the transducer-cell and some samples.
The Transducer-Cell. Notice the special form of the sample under test, and the formula used to compute both shear and compressional wave velocities.
Many British companies were approached in 1988 in order to license the product, namely, CNS Electronics Ltd, Sonatest Plc, and Phoenics Inspection Systems Ltd.
E-mail: bouhadjera@mail.univ-jijel.dz