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Investigation of thermomechanical processes in miniature membrane elastic elements

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

Journal of Achievements in Materials and Manufacturing Engineering

2020

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.

Multiparameter fault identification in elastic elements of constructions based on artificial neural networks

Krasnoschekov A.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

2011

z. 99

33-35

Identification of defects is a critical aspect in the operational safety and func- tionality of elastic structures. It’s well known that changes in a structure of the material, entail a change in its dynamic properties. One of the most commonly used methods for determination of these properties is modal analysis, with witch we obtain spectrum of natural frequencies and forms of investigated object. This data can be used to identify presence of the defect and it's quantative parameters (like location or size). In recent years many studies in this direction were held and artificial neural networks (ANN) are increasingly used for reconstruction of inhomogeneities [1,2]. In this article we propose a method that includes the complete cycle of designing ANN for identification of defects in a given 3-D object: starting from a model and ending with location of sensors on the object's surface and trained ANN. The problems of constructing simulation model of the object, optimal placement of sensors and subsequent identification of the defect were solved. We've also investigated possibilities of application of different architectures and training algorithms of ANN, and analyzed the influence of errors on the accuracy of determination of the defect's parameters. Simulation model in the purposes of the study in ANSYSŽ we've built 3-dimensional FE mod- el of the beam of rectangular cross section with a through crack which is coming out on top of the face (Fig. 1). The left end is rigidly clamped, right - free.