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Non-destructive testing of ferromagnetic materials using hand inductive sensor

100%

Deyneka R. , Tykhan M. , Markina O.

2019

tom Vol. 98, nr 1

32--41

Purpose: The need for reliability of industrial structures, machines and other equipment requires more accurate testing of structural materials, especially ferromagnetic materials. Therefore, it is important to improve existing or develop new, more accurate methods and devices for non-destructive testing. Design/methodology/approach: Non-destructive testing of ferromagnetic materials is carried out by surveying a local magnetic field or determining the section magnetic resistance of a material using the proposed new type of sensor as the hand inductive element on a toroidal core with additional magnetic cores. Findings: This sensor has a simple design and high response characteristic, which has been confirmed experimentally. Such a sensor can be used for testing welded joints by the proposed method, which is based on measuring the magnetic resistance of the welding area. Research limitations/implications: Analytical physical processes research that occurred in the magnetic core material of the sensor coil core, used as a sensitive element, is complicated by the nonlinearity of the magnetization curve of the material of the core of the sensitive element and the lack of a single analytical relationship to fully describe the magnetization process of ferromagnetic materials of inductive elements. Therefore, each copy of the sensor will be an individual graduation. Practical implications: The proposed version of the hand inductive sensor allows to perform non-destructive testing during the operation of ferromagnetic structures and without special requirements to external conditions with low costs and the possibility of computer processing of data. Originality/value: The use of the nonlinearity zone of the magnetization curve of the inductive element core material made it possible to obtain a variant of a magnetic sensor that is close in sensitivity to fluxgate and, at the same time, is much simpler in design using non-deficient materials. The use of a ferrite core with low saturation induction requires a small circuit supply voltage, but a generator power reserve. The proposed hand inductive sensor is sensitive to the presence of extraneous ferromagnetic objects, and responds only to a magnetic field. The high magnetic resistance of the inductive sensor allows it to be used on uneven and dirty surfaces. High sensitivity allows to detect small deviations of the magnetic fields of dispersion of a welded joint with their comparison along the entire joint length. All of this gave new opportunities for more accurate non-destructive testing of structural elements and materials.

Investigation of thermomechanical processes in miniature membrane elastic elements

100%

Tykhan M. , Dilay I. , Markina O. , Markovych V.

2020

tom Vol. 98, nr 1

24--31

Purpose: The demand for the devices structures reliability and machines requires understanding elements operation, in particular elastic elements, under the effect of nonstationary temperature factors. Therefore, it is important to investigate the behaviour of these elements under variable temperature effecting. Design/methodology/approach: In this article, the temperature field and the thermal stresses of the membrane type elastic elements, as well as the thermal deformation of its body part were investigated by the method of numerical analysis. The theoretical results have experimental confirmation. Findings: The article shows possibilities significantly reduce the thermal stress in an elastic element, thereby increase its functional and structural reliability by varying the geometric parameters of the elastic element, the materials selection, and body shape. Research limitations/implications: Numerical modelling of thermal processes requires accurate information about the physico-mechanical properties of materials and heat-exchange coefficient, which in practice may differ from the theoretical ones. Therefore, experimental confirmation of research and decisions is needed. The influence of the "hot" thermal shock was investigated. There is performed interest to investigate the "cold" thermal shock. Practical implications: The obtained results allow creating elastic elements with better functional characteristics for operation in a wide temperature range. They can also be used in the designing of elastic elements not only of membrane type. Originality/value: Performed investigation of thermomechanical processes in the membrane elastic element has revealed important features of its temperature deformations with nonstationary thermal influence. Namely, the nature of thermal deformations can be changed by selecting the geometrical parameters of the element, its material, as well as the conditions of heat-exchange conditions with mating member (body). In this way, it is possible to obtain a controlled deformation and to design the elastic elements with predetermined functional tasks. On the other hand, the design of the membrane element body can create elastic hinges, which allows reducing the thermal stress in the membrane, which significantly increases the reliability of the element operation of this type in conditions of non-stationary temperatures. In general, the conducted investigations allow efficient design of elastic elements for devices, sensors and other precision mechanisms.