Monte Carlo methods have been applied in deriving values for parameters characterizing the scattered-background reduction behind absorbers made of iron, aluminum, and plexiglas with double slot stops for the scanning beam for x rays with Kramers spectrum.
Short combined transducers distinguished by a short wave length are considered. The advantages of a short transducer in operation under conditions of free vibrations are shown and the characteristics of its sensitivity in frequency, amplitude, and amplitude-frequency processing of information are shown.
Two requirements for systems for continuous inspection of plate material structures are named, determination of the coordinates of fatigue cracks and detection of areas of corrosion wear. For solution of the first problem a new principle of construction of acoustic emission systems with combined channels is proposed. A variation of calculation of the probability of overlapping of signals is proposed and it is shown that for small activities of the courses (initial stages of fatigue crack development) significant simplification of the equipment may be obtained. For solution of the second problem use of the dispersion properties of Lamb waves is proposed. Equations making it possible to theoretically determine the size of the wear area and the residual thickness of the plate are obtained.
Problems are examined using expert systems of solving problems of nondestructive inspection and technical diagnostics. The authors proposed a classification of nonformalized problems in this area which can be solved efficiently by expert systems. Examples of the currently available expert systems are examined to determine the possibilities and special features of constructing these systems for nondestructive inspection and technical diagnostics. Special attention is given to analysis of tendencies and problems of developing these systems and ways of overcoming these problems. Directions of the development of expert system for vibro diagnostics at the Spektr Scientific and Production Association (Moscow) are discussed.
The influence of the damping material and the parameters of the two matching layers on the characteristics of an acoustic transducer with delay lines made of polystyrene are theoretically and experimentally examined. Recommendations are given for choosing the thickness of the matching layers.
The article investigates the method of contactless nondestructive inspection of the conductivity of conductors based on measurement of the Q factor of a SHF resonator with a conductor in the form of a thin plate or disk placed in the antinode of the magnetic field of the resonator.
Experiments were carried out to determine the attenuation coefficients of wide and narrow beams of radiation of MIRA-2D pulsed x-ray equipment in a steel up to 20 mm thick. The results made it possible to calculate the parameters of x-ray images in irradiating welded joints.
Functional relations are derived for interference caused by a two-layer inspected object in the flux distribution of the electric field of an electric charge primary transducers. Algorithmic methods of disturbing the parameters of a conventional plane permanent joint, represented by dissimilar dielectrics, without their failure, are examined.
The article deals with the theoretical and experimental investigation of the reflection of Rayleigh waves from crack-like defects of finite length whose planes are oriented perpendicularly to the axis of the transducer. In radial approximation analytical formulas for the amplitudes of the echo signals are obtained. Recommendations for the selection of working frequencies are given. Diagrams of amplitude-distance-extension of defects are calculated and experimentally verified.
The article suggests a formula for calculating the central demagnetization factor of ferrmomagnetic cylindrical rods for different ratios of the length of the specimen to the diameter and different magnetic susceptibility of the material. An analysis is carried out of the accuracy of the formula and of the indispensable accuracy of determining the demagnetization factor in magnetic measurements. Recommendations are given for the choice of the method of determining the demagnetization factor, whether it is to be done by calculation or experimentally.
Four methods of inspecting the dielectric films: copper-gelatin, bubble, probe, and the method of nematic liquid crystal (NLC method), are compared. It is shown that the largest amount of information is provided by the NLC method: together with continuous defects, it makes it possible for this method to be used to determine potentially dangerous regions in dielectrics. It is proposed to use the NLC method as a certification method.
An analysis is made of the acoustic circuit of an angle-beam transducer for reflection of an ultrasonic wave from a crack entering onto the opposite free surface. Calculation of the field of relection based on the results of [1, 2] was compared with an experiment made on a specimen with a groove of variable depth. The analysis covered the area of angles of the transducer prism including the first critical.
A method is presented for design of plane aperture ultrasonic transducers in the form of a rectangle or parallelogram having a highly directional pattern with the specified level of side lobes in two principal sections and in all sections. The necessity of matching the form of the opening with the necessary directional pattern is shown.
The article describes an ultrasonic installation intended for detecting surface defects and determining their depth in rolled billets with square profile. The main technical characteristics of the installation are presented.
A simple method is proposed for measurement of the effective values of the complex dielectric permeability epsilon of sheet materials including of composite materials with spatial nonuniformities having a dimension comparable to the wave length of the radiation. The method is based on measurement of the modulus of the coefficient of reflection of an electromagnetic wave and a flat metal screen located beyond it in relation to the distance d between the specimen and the screen. The value of epsilon was found from the measured R(d) relationship by methods of nonlinear programming. An analysis is given of the measurement errors and evaluations are given of the boundaries of applicability of the method.
A method is proposed for determination of the uniformity of semiconductor materials transparent and opaque to infrared radiation on the basis of use of carriers developed for recording of infrared interferograms.
The article deals with the resistance of residual magnetization of heat-treated structural steels to tensile, compressive, torsional, and reversed cyclic elastic deformations. It was established that there is an unambiguous correlation between the tempering temperature and the changes of residual magnetization caused by elastic stresses. In steels containing 0.3-0.4% carbon reversed cyclic loads lead to an unambiguous dependence of residual magnetization on the tempering temperature. The monotonic changes of residual magnetization accompanying the increase of elastic stresses in a ferromagnet make it possible to estimate these stresses, and also to devise a sensor storing the maximal stresses in structural elements.
The article presents the results of the application of impulse electron accelerators for the contactless acoustic quality control of products made of current-conducting materials. It considers the main features of the radiation method of generating ultrasound in solid bodies and shows the effectiveness of its combination with contactless electroacoustic reception of excited ultrasonic oscillations.
The results are presented of modeling and experimental investigation of the directional properties of a linear equidistant ultrasonic transducer array with different distributions of excitation with respect to the aperture. The adequateness of the earlier published calculation method is shown.
Basic technical characteristics and application examples are given for a new generation of Soviet commercial computerized tomographs.
