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Том 53, № 11 (2017)
- Год: 2017
- Статей: 8
- URL: https://journal-vniispk.ru/1061-8309/issue/view/11314
Magnetic Methods
Computational relationships for the development of software for calculating magnetostatic fields from flaws in arbitrarily shaped ferromagnetic products
Аннотация
Based on the integral equation for the stray magnetic field strength inside a magnetized article, computational relationships have been derived in the form of a matrix equation that is convenient when developing software for modeling the distribution of magnetization in arbitrarily shaped articles with different flaws and for calculating and imaging external magnetic fields of the magnetized article. On this basis, a program has been developed that is most suitable for the case where the article boundaries and flaws can be sufficiently accurately defined on a three-dimensional grid with identical rectangular cells.
755-764
A calculation method for evaluating defect parameters in steel
Аннотация
This work aims at taking another step forward towards the solution of the inverse problem. A calculation method has been proposed for evaluating the size of defects by means of a universal polynomial equation that allows one to estimate defect dimensions in various materials. A polynomial equation for extended defects that establishes relationship between the magnetic field of a defect and its length and occurrence depth has been composed.
765-771
A procedure and device for calibration-free determination of residual compression stresses in low-carbon steels deformed by tension
Аннотация
A procedure for determining the residual compression stresses in tension-deformed low-carbon steels has been proposed that does not involve pre-calibration of the device with standard samples for the case where magnetic anisotropy is mainly determined by mechanical compression stresses. A new design of the attachable measuring transducer is presented for experimental determination of the induced magnetic-anisotropy field within local areas of lump ferromagnetic objects. The legitimacy of evaluating compression stresses with this procedure has been proved experimentally.
772-778
Measuring coercive force in local domains of a sample
Аннотация
A method has been proposed for determining the coercive force in local domains of bulk samples magnetized normally to the surface. The method is based on local measurement of the normal magnetic-field component at the sample surface, in the gap between the sample and the pole of a magnetizing device. The coercive force is determined by the magnetic field for which local magnetization in the measured domain becomes zero. Conditions for the correctness of coercive-force measurements have been established.
779-784
Acoustic Methods
Physical basics of evaluating elastic characteristics of anisotropic composites by ultrasonic method
Аннотация
As a result of analyzing the generalized Hooke law and wave equations for an anisotropic medium, computational expressions have been derived for evaluating the elastic constants of orthotropic, transversely isotropic, and isotropic media using the propagation velocities of longitudinal and shear elastic waves measured with the pulsed ultrasonic method in the corresponding directions.
785-799
On the resonance and antiresonance frequencies of a plate piezoceramic transducer
Аннотация
Problems related to applying the concepts of resonance and antiresonance frequencies of a plate piezotransducer have been studied. The case of a plate unilaterally loaded on an aqueous medium has been researched. It has been shown that the concept of the antiresonance frequency determined with the use of an elastic modulus c33D can be applied only conditionally, still allowing one to calculate frequency characteristics for different values of a squared electromechanical-coupling coefficient. Notwithstanding the conditional nature of the term “antiresonance”, its practical use does not cause any difficulties.
800-804
Assessment of thermally deteriorated concrete by drilling resistance test and sound level
Аннотация
Concrete being the most versatile and widely used construction material finds application in varied range of structures. Many of these like chimneys, furnaces and reactors have to sustain high temperatures and perhaps all structures have to perform at elevated temperatures in the event of fire accidents. Concrete at elevated temperatures undergoes changes in its physical structure and chemical composition and loses its strength characteristics. Need for quick assessment of fire damaged concrete for strength characteristics, has motivated this work, which explores the potential of drilling resistance test on concrete as a Non Destructive Testing (NDT) tool. Drilling times, penetration depths and sound level measurement while drilling have been recorded and analysed to provide monograms that are handy as reckoners in failure forensics.
805-815
Erratum
816-816