Probe configurations
Ultrasonic probes using the new rubber have been developed in both single and twin crystal format for operation at frequencies from 2.5 MHz to 10 MHz for both the wheel probe configuration and static probes. Static probes and twin crystal wheel probes are directly coupled to the rubber, but all single crystal wheel probes are filled with water and use soft focused transducers to ensure maximum transmission of ultrasound through the tyre footprint. Single crystal wheel probes are available in compression wave (straight beam) format or in forward or sideways looking shear wave format. Shear wave angles from 45" to 70" are available.
Research by the NDT group at Imperial College led to the development of this genuine alternative to liquid or gel coupling of ultrasound. It is based around a low-loss rubber whose attenuation is similar to that of Perspex and whose acoustic impedance is very close to that of water. These properties make it possible to construct both wheel and static probes operating at frequencies of 2.5 MHz and above. Probes using the new rubber are driven from conventional ultrasonic test sets and no extra signal processing or amplification is required. A load on the probe of under 1Kg is required to ensure stable coupling between the probe and the test surface.
SilverWing has been appointed by IMPEL (Imperial Exploitations Ltd) to manufacture and market this exciting development in ultrasonic transducers. A comprehensive range of wheel and static probes have been designed, together with manipulators and systems, to meet the varied requirements of the aerospace and petrochemical industries. |
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