Reciprocity calibration of ultrasonic contact transducers

摘要

The extension of the reciprocity calibration method widely used innmedical ultrasonics to nondestructive pulse-echo transducers isnpresented. It is shown that the self-reciprocity procedure originallyndeveloped for immersion transducers can also be applied to contactntransducers, which are mainly used for the investigation of solids. Thensensitivity of the contact transducers used was calculated with the helpnof two models which simulate the behavior of the transmitter-receivernarrangement within the whole frequency range investigated, namely 2-12nMHz. The procedure needed to determine the diffraction losses associatednwith the test objects such as half cylinders and half spheres is alsonpresented. Half cylinders or half spheres are needed when the ultrasonicnwave does not have a normal incidence on the test object. The calculatedndiffraction loss for the half cylinder was also experimentally verified.nGood agreement obtained between diffraction loss measurements and thenmodel predictions confirms that the calculated diffraction loss of thenhalf cylinder is suitable for use in practical investigations. Thencalibration procedure described enables ultrasonic measurementsnperformed with different contact transducers and devices to be compared.nThis is of great importance in many applications, as for example innperiodic routine inspections of the components of nuclear facilities