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.
Ultrasonic oblique incidence for improved sensitivity in interface weakness determination
Abstract An ultrasonic oblique incidence technique is proposed to help solve the problem of interfacial weakness detection between adhesive and adherend in adhesively bonded structures. The technique employs transverse waves with an angle of incidence chosen from numerically established angular characteristics of the reflection factor for different interface boundary conditions. The interface with imperfections is modelled as a bond having a rigidity of a finite value, covering a range of delamination from ‘smooth’ to a ‘welded’ or perfect bond. Experimental measurements carried out on adhesively bonded aluminium-epoxy resin specimens illustrate quite nicely the increased sensitivity of using transverse waves for interfacial weakness detection. To improve sensitivity, a signal feature in the frequency domain is also used.