Measurement of characteristic parameters of ultrasonic flaw detectors
In order to guarantee the liability and accuracy of ultrasonic flaw detectors, a system is developed for measuring the characteristics of ultrasonic flaw detectors. The parameters which evaluate the characteristics of the pulse excitation circuit include pulse amplitude voltage, pulse rise time, pulse duration, pulse repetition frequency, peak frequency, bandwidth and output impedance. The parameters which evaluate the characteristics of the amplifier circuit include cut-off frequency, pass band, dynamic range, input impedance and equivalent input noise. The parameters which evaluate the coupling characteristics of these two circuits include crosstalk and blocking time during transmission.
Ultrasonic Flaw Detector for Checking the Quality of Cast Semifinished Products Made of Steel 04Kh13T3R1F (ChS82-Sh)
This article examines the feasibility of using ultrasound to inspect cast semifinished products of steel 04Kh13T3R1F (ChS82-Sh) obtained by electroslag remelting. A method for such testing has been developed with the use of a USK 7S flaw detector (made by the company KRAUTKRAMER) and a set of AVG scales of type ONMK ITTs for the B1S transducer. Good agreement was obtained between the ultrasonic test reults and the results of a macrostructural evaluation performed by etching.
The ultrasonic vibration characteristics of adhesive joints
The natural frequencies of the longitudinal (through thickness) modes of an adhesive joint have been predicted using receptance analysis and measured using ultrasonic spectroscopy. Excellent agreement has been obtained between the predicted and measured frequencies of joints with a wide range of adhesive thicknesses and moduli. At low adhesive thicknesses, the modes tend to occur in pairs, but, at higher thickness, this pairing no longer occurs. This phenomenon has been explained in terms of the mode shapes of the different modes and the role of the adhesive layer in determining their frequencies. The variation of the apparent vibration damping with adhesive thickness has also been explained in terms of the mode shapes of the joint. The results indicate that it should be possible to calculate the thickness and modulus of the adhesive layer from measurements of the resonant frequencies of the joint. This would represent a significant advance in the nondestructive testing of adhesive joints.