ULTRASONIC PROBE FOR THE INSPECTION OF TIMBER CONCRETE AND LIKE MATERIAL

摘要

An ultrasonic probe for the inspection of timber, concrete and other like materials wherein a matched pair of such ultrasonic probes, comprising of piezoelectric ceramic transducer elements is used, one probe works as the transmitter and coverts the electrical pulses of required duration and frequency, fed to it from the transducer existing pulse generator of the ultrasonic testing equipment, into an ultrasonic beam, this beam travels through the specimen under test when the invented transmitting probe is placed on one side of the specimen and the beam is picked up by the receiving probe placed on the other side of the specimen, the ultrasonic beam is again converted back into the corresponding electrical signal by the receiving probe, which is amplified by the receiver amplifier and is consequently displayed on the cathode ray oscilloscope screen, whereby the time delay (in Mocro-seconds) produced by introducing the specimen in between the probes, can be measured directly with the help of a fixed delay circuitry of the ultrasonic testing equipment, by choosing an arbitrary reference point corresponding to that position of the probe when they were placed in direct contact with each other, wherein the CRO time base generator is in synchronization with the pulse generator, whereby from the knowledge of time delay (in micro-seconds) and the length of specimen, the ultrasonic velocity in the specimen can be obtained, characterised in that we have found that by providing a back plate of half wavelength thickness, the piezoelectric ceramic transducer, vibrating at its fundamental resonant frequency is more efficient in sending or receiving ultrasonic energy through the specimen under test thereby increasing the sensitivity of the test equipment, whereby keeping the transducer in prestressed position and by providing a thin layer of grease or oil in between the transducer and the front plate better transfer of energy takes place from the transducer to the test specimen and test specimen to the transducer.