Advances in Vibration Analysis Research

Ebrahimi, Farzad

doi:10.5772/639

Cited by 17 publications

(2 citation statements)

References 165 publications

(210 reference statements)

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“…A peculiarity of dynamic loads is that under the action of an external force on the girder, the considered system begins to vibrate. The amplitude A, (m) of vibrations can be determined by the expression (Strelkov, 2005;Ebrahimi, 2011;Gusev & Novoselova, 2017):…”

Section: Figure 3 Computational Scheme For the Determining The Unknomentioning

confidence: 99%

“…When studying the phase relationships between the action of an external force and the oscillator response, it was previously determined that the response of the oscillator is always lagging behind the action (Strelkov, 2005;Ebrahimi, 2011). Therefore, in the case of an external force acting on the girder, when studying the damped vibrations of a modelled system that has a yielding support, if movements in the same direction are performed simultaneously, the compared spectra should differ from each other only by a shift.…”

Section: Figure 3 Computational Scheme For the Determining The Unknomentioning

confidence: 99%

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Phenomena of stability of the coal seam roof with a yielding support

Podkopaiev¹,

Gogo²,

Yefremov³

et al. 2019

Min. miner. depos.

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Purpose. Determining the conditions and parameters for ensuring the stability of the coal seam roof with a yielding support in the area adjacent to face and behind it under the influence of dynamic loads based on the analytical and laboratory studies. Methods.To achieve the purpose set, analytical studies have been carried out using the basic principles of the theory of elasticity and vibrations, the hypothesis of girders and the hinged-block displacement of the stratified rock stratum. Also, the laboratory studies of models from equivalent materials have been performed, in which the coal seam roof is presented in the form of a girder having a yielding support with variable rigidity from the filling material under dynamic load.Findings. As a result of performed studies, the phenomenon has been determined that the condition for the stability of the coal seam roof is a geometric parameter that reflects moving of the girder with a yielding support, under the force impact of a falling load with a known mass and the physical-geometrical characteristics of the deformable system. It has been determined that as a result of a change in the spans length, a change in the flexural rigidity of the girder occurs, which means that the yield influence of the same supports on the stability of the coal seam roof is different. The values have been set and the relationship has been studied of the physical-mechanical characteristics of the filling mass as a yielding support.Originality. It has been proven scientifically that the stress-strain state (SSS) of a system in which the coal seam roof is studied as a girder depends on the physical-geometrical characteristics of the system, as well as the type and place of applying the external load, in case when the law of the girder movement in time is determined.Practical implications. The effective supporting of the undermined rock stratum in the working part of the longwall face and behind the face is achieved by placing the yielding supports in the mined-out space or by using the backfill in the mined-out space while conducting the stope operations, thus, increasing the efficiency of measures to protect the labour of miners in coal mines.

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Section: Figure 3 Computational Scheme For the Determining The Unknomentioning

confidence: 99%

Section: Figure 3 Computational Scheme For the Determining The Unknomentioning

confidence: 99%

Phenomena of stability of the coal seam roof with a yielding support

Podkopaiev¹,

Gogo²,

Yefremov³

et al. 2019

Min. miner. depos.

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Analysis of the Problem of Harmonic Waves in Elastic Bodies and its h-Adaptive Finite-Element Approximation

Kvasnytsia

Shynkarenko

2023

J Math Sci

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Nonlinear Modal Analysis of Frictional Ring Damper for Compressor Blisk

Sun

Yuan

Denimal

et al. 2021

Journal of Engineering for Gas Turbines and Power

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The use of integrally blisk is becoming popular because of the advantages in aerodynamic efficiency and mass reduction. However, in an integrally blisk, the lack of the contact interface leads to a low structural damping compared to an assembled bladed-disk. One emerging damping technique for the integrally blisk is based on the use of friction ring damper which exploits the contact interfaces at the underneath of the disk. In this paper, three different geometries of the ring dampers are investigated for damping enhancement of a blisk. A full-scale compressor blisk is considered as a case study where a node to node con- tact model is used to compute the contact forces. The dynamic behaviour of the blisk with the ring damper is investigated by using nonlinear modal analysis which allows a direct estimation of the damping generated by the friction interface. The damping performance for the different ring dampers are evaluated and compared. It appears that the damping efficiency as well as the shift in the resonant frequency for the different geometries are highly related to the nodal diameter and contact pressure/gap distributed within contact interface. The geometry of the ring damper has significant impact on the damping performance.

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Advances in Vibration Analysis Research

Cited by 17 publications

References 165 publications

Phenomena of stability of the coal seam roof with a yielding support

Phenomena of stability of the coal seam roof with a yielding support

Analysis of the Problem of Harmonic Waves in Elastic Bodies and its h-Adaptive Finite-Element Approximation

Nonlinear Modal Analysis of Frictional Ring Damper for Compressor Blisk

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