Wyniki wyszukiwania - Biblioteka Nauki

1

Taking account of the shift and inertia of rotation in problems of diagnostics of the spectra of critical forces mechanical systems

100%

Orobey V. , Nemchuk O. , Lymarenko O. , Piterska V. , Lohinova L.

Diagnostyka

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2021

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tom Vol. 22, No. 1

39--44

EN

Diagnostics of stability of the cores constructions, elements of the carrier system of the ship and port facilities, reduces to the definition of critical forces, excess which causes a transition of the system from one equilibrium state to another. Such a transition often leads to the destruction of the constructions or other forms of accidents, and therefore it is extremely undesirable and for practice it is important to knowledge of a specific spectrum of critical forces and their corresponding forms of loss of stability.

2

Diagnostics of stabilization modes of shape strand ropes

86%

Orobey V. , Nemchuk O. , Lymarenko O. , Piterska V. , Sherstiuk O. , Lehetska I.

Diagnostyka

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2022

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tom Vol. 23, No. 4

art. no. 2022409

EN

The work is devoted to the diagnostic issues of the possibilities of technological balancing of steel shaped strand ropes of lifting and transport equipment, which is of great scientific and practical importance, since it will improve their performance. A literature review showed that this topic is practically not covered and only the issues of straightening (bending) strands, which are not effective enough, are considered. The research objective and the problem that must be solved to obtain ropes with better quality characteristics (greater durability and strength) have been formulated. A more accurate expression for the technological torque of shaped strands is presented. The ways of reducing the torque as a harmful factor are indicated. Diagnostics of possible options for technological balancing of ropes was carried out. Rational modes of manufacturing shaped strand ropes have been determined.

3

Consideration of shear, rotational inertia and compressive force during transverse vibrations of structural beam elements

86%

Orobey V. , Nemchuk O. , Lymarenko O. , Piterska V. , Sherstiuk O. , Semenov P.

Diagnostyka

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2024

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tom Vol. 25, No. 1

art. no. 2024101

EN

The procedure for taking into account shear and rotational inertia in the case of transverse vibrations of beam elements of material handling vehicles with different conditions of fastening (support) is considered. The dynamic model of the rod element is supplemented with compressive forces with a fixed line of action and monitors the angle of rotation of the rod. The Fourier method of separation of variables in the harmonic vibrations of beams is applied. This made it possible to obtain a differential equation, kinematic and static parameters in the amplitude state. The resulting differential equation is integrated, the fundamental functions are normalized, and the complete solution is presented in matrix form with initial parameters. Four cases of fundamental functions are revealed. For beam elements with different support conditions, the vibration frequency has been refined. With hinged support, the first 5 frequencies of this work coincide with the frequencies obtained by another approach.

4

Diagnostics of the strength and stiffness of the loader carrier system structural elements in terms of thinning of walls by numerical methods

86%

Orobey V. , Nemchuk O. , Lymarenko O. , Piterska V. , Sherstiuk O. , Romanov O. , Tkachuk K.

Diagnostyka

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2021

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tom Vol. 22, No. 3

73--81

EN

Modern gantry cranes are an indispensable element of large industrial and transport enterprises. Port handling equipment is operated under conditions of complex spatial loading of varying intensity, as well as under conditions when the walls of structural elements are thinned in the crane carrier system. During the operation of handling equipment in ports, at construction sites, in machine-building industries, in addition to the external load, aggressive media act on the carrier system elements, which leads to various types of wear: corrosive, abrasive and mechanical. Monitoring of the state of handling equipment structures is a very important task of diagnosing the state of the material of elements of the carrier system of cranes and transporting machines. An important and urgent scientific and technical problem of taking into account the influence of aggressive environment on the stress-strain state of the metal structures of gantry cranes is considered. It is noted that during corrosion, a significant thinning of the walls of structural elements occurs. The safety of crane operation requires this factor to be taken into account. It is proposed to use modern numerical methods for this, i.e. the boundary element method (BEM) and the finite element method (FEM). The implementation of these methods is performed in the Matlab programming and modeling environment (BEM), and the FEM is used in the Ansys package. In accordance with the technologies of these methods, the design diagrams of the lower girders and the crane structure as a whole were formed. Exact models of strain of crane elements during transverse bending and constrained torsion are given. Calculations of the stressstrain state of the crane metal structures have been performed. On the basis of a preliminary field study, a numerical model is proposed for diagnosing the strength and stiffness characteristics of the carrier system of handling equipment using the BEM and FEM, which has never been used in the world. Conclusions are drawn about the influence of the thinning of the walls of metal structures on the values of normal and tangential stresses.