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Vol 52, No 4 (2016)
- Year: 2016
- Articles: 8
- URL: https://journal-vniispk.ru/1061-8309/issue/view/11282
Acoustic Methods
Detecting transverse material boundaries in multilayer anthropogenic structures
Abstract
The Kirchhoff approximation has been used to analytically determine the field that is generated by the reflection of an acoustic wave from an interface with a sharp acoustic impedance gradient. Visual formulas have been derived to describe the incoming signal when the boundary is exposed to a pulsed point source. On the basis of numerical modeling and an experimental study of multilayer systems, the suggested approach is applicable for detecting flaws in planar and cylindrical structures under pulse excitation. An algorithm is given for improving the accuracy of locating the rupture boundary. It is based on revealing correlations in wave field parameters at various points in the system.
185-196
Generating short pulses at the output of an emission–reception system when the emitter is excited with pulses with a special shape
Abstract
An emission–reception system that consists of two identical piezoelectric crystal plates is considered. The emitter is excited by a half-cycle of harmonic electric voltage at the eigenfrequency. Formulas have been derived for the emission mode and for the use of compensating electric pulses for the emitter and the receiver. On the basis of these formulas, calculations have been made and counterpart graphs have been provided in order to show, as an example, that electric pulses that are four and five half-cycles long can be generated at the output of the receiver.
197-205
A local method for loading a tested object during acoustic-emission diagnostics
Abstract
A new acoustic-emission diagnostics method in which there is no need to load an entire structure has been studied. This method of monitoring (as a conventional acoustic-emission method) is based on making a deformation of the tested surface; however in this case, the load is applied to a preliminarily chosen site of the tested object in the most dangerous area.
206-211
Thermal Methods
Ultrasonic infrared thermography in non-destructive testing: A review
Abstract
Potentials of a novel non-destructive testing technique called ultrasonic infrared thermography (UIT) have been widely recognized for the last decade. This technique is promising for many practical industrial applications being of interest for academic researchers who deal with thermomechanical problems. Significant improvements in the performance of infrared imager have also contributed to increasing popularity of this inspection technique. This paper presents an introduction to the use of UIT in NDT, combining a review of earlier and later research with some experimental illustrations.
212-219
Magnetic Methods
The detection of real defects in ferromagnetic objects using a magnetic-field imaging film
Abstract
Tracer patterns of real defects during magnetic monitoring of ferromagnetic objects using a magnetic-field imaging film are presented. The results of production tests on the monitoring of a real object are demonstrated.
220-225
Eddy currents and conducting and magnetizable spherical inclusions fields in a nonmagnetic medium
Abstract
The calculation results of the non-linear dependencies between eddy currents and spherical inclusions fields and parameters of these inclusions and external alternating field are discussed. These dependencies can be useful, both to analyze the scattering fields of spherical inclusions under nondestructive testing and to calculate the heating and melting processes of such bodies. The formulas are given in a from that is convenient for programming.
226-234
X-Ray Methods
235-244
Optimization of energy window for gamma densitometer based backscatter method in oil industry
Abstract
In this paper, we describe the results of various calculations performed for a design of the interference gauges that use the gamma-ray backscattering method with different scatter windows. The Pb barrier as shielding placed between 4 mCi 137Cs sealed radioactive source and a NaI (Tl) scintillation detector (1 inch in diameter—2 inch in height). Upon interaction with the material the scattered radiation, due to Compton process, was measured by NaI(Tl) detector. Using Compton scattered photons and review of the scattered photons in substance, by measuring of gamma-ray photons distributed, the density of materials can be obtained accurately. The results present for different scatter energy windows which 39–273 and 39–390 keV scatter windows have the best ΔX, STD and signal to noise.
245-249