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Article
Publication date: 20 April 2020

Peng Sun, Weifang Chen, Yusu Shen and Dan Wang

As an important part of the rotor system, the damping coefficient of ball bearing has a great influence on the dynamic characteristics of the system. This study aims to propose a…

Abstract

Purpose

As an important part of the rotor system, the damping coefficient of ball bearing has a great influence on the dynamic characteristics of the system. This study aims to propose a theoretical calculation method and an experimental test method to obtain the damping coefficient of ball bearing.

Design/methodology/approach

Based on Hertzian contact theory and elastohydrodynamic lubrication theory, the point contact oil film damping analysis model of ball bearing is established. The comprehensive damping calculation method considering external radial load, centrifugal force, ball spin, rotational speed and lubricating oil film is derived. The multigrid method is used to obtain the oil film pressure and thickness distribution in the contact zone. The variation trend of comprehensive damping with bearing radial load, rotational speed, oil film thickness and viscosity is analyzed. The test platform is designed and the influencing factors of damping are tested.

Findings

The validity of the model and reliability of the test device are verified by comparing the good consistency obtained in the work. The results show that the comprehensive damping of ball bearing increases with the increase of radial load and decreases with the increase of rotational speed.

Originality/value

At present, the existing bearing damping model can achieve approximate calculation of damping, but the factors considered in these models are not comprehensive enough. Besides, few studies exist regarding test platform of bearing damping, and a perfect test plan has not yet been formed. In this paper, the comprehensive damping calculation model of ball bearing is improved, and a complete experimental scheme is proposed to provide reference for the comprehensive damping theory and experimental research of bearing.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0342/

Details

Industrial Lubrication and Tribology, vol. 72 no. 7
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 7 September 2021

Ming Huang, Zhiqiang Zhang, Peizi Wei, Fei Liu and Youliang Ding

In order to make sure of the safety of a long-span suspension bridge under earthquake action, this paper aims to study the traveling wave effect of the bridge under multi-support…

124

Abstract

Purpose

In order to make sure of the safety of a long-span suspension bridge under earthquake action, this paper aims to study the traveling wave effect of the bridge under multi-support excitation and optimize the semi-active control schemes based on magneto-rheological (MR) dampers considering reference index as well as economical efficiency.

Design/methodology/approach

The finite element model of the long-span suspension bridge is established in MATLAB and ANSYS software, which includes different input currents and semi-active control conditions. Six apparent wave velocities are used to conduct non-linear time history analysis in order to consider the seismic response influence in primary members under traveling wave effect. The parameters α and β, which are key parameters of classical linear optimal control algorithm, are optimized and analyzed taking into account five different combinations to obtain the optimal control scheme.

Findings

When the apparent wave velocity is relatively small, the influence on the structural response is oscillatory. Along with the increase of the apparent wave velocity, the structural response is gradually approaching the response under uniform excitation. Semi-active control strategy based on MR dampers not only restrains the top displacement of main towers and relative displacement between towers and girders, but also affects the control effect of internal forces. For classical linear optimal control algorithm, the values of two parameters (α and β) are 100 and 8 × 10–6 considering the optimal control effect and economical efficiency.

Originality/value

The emphasis of this study is the traveling wave effect of the triple-tower suspension bridge under multi-support excitation. Meanwhile, the optimized parameters of semi-active control schemes using MR dampers have been obtained, providing relevant references in improving the seismic performance of three-tower suspension bridge.

Details

International Journal of Structural Integrity, vol. 12 no. 5
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 10 September 2020

Zhiming Zhao, Rui Zhang, Feng Ji and Xiaoyang Yuan

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing system is…

Abstract

Purpose

High power and speed are new demands for rotating machinery which needs the journal bearings with high dynamic characteristics. The critical speed of the rotor-bearing system is one of the most significant parameters to evaluate the dynamic characteristics. This paper aims to investigate the theoretical and experimental analysis of a rotor system supported by large diameter elliptical bearings.

Design/methodology/approach

To obtain the theoretical and experimental support for rotor-bearing system design, dynamic characteristics theoretical analysis based on the finite difference method is given and an experiment focuses on critical speed identification is carried out.

Findings

The theoretical calculation results indicate that the critical speed is near to 800 rpm and there is no large vibration amplitude round working speed (1,500 rpm). Using the test bench in the factory unit, vibration data including three experimental processes are obtained. According to the vibration data, the critical speed is identified which also indicates that it is stable when working at 1,500 rpm.

Originality/value

The design method for the rotor system supported by large diameter elliptical bearing can be obtained by the theoretical and experimental results shown in this paper.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0122/

Details

Industrial Lubrication and Tribology, vol. 73 no. 1
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 1 September 1998

James Douglas

Continues to examine the provision of damp proofing in ground‐supported floors. Considers the problems associated with dampness in and damp proofing of floors in old buildings…

1507

Abstract

Continues to examine the provision of damp proofing in ground‐supported floors. Considers the problems associated with dampness in and damp proofing of floors in old buildings. Examines the options for replacing the original defective floor with a ground‐bearing floor. Indicates that when a new DPM is installed, moisture can be diverted from the underside of existing ground floors to the external walls. Shows that in some instances the provision of a DPM may not be essential in replacement ground floor slabs provided that certain precautions are taken.

Details

Structural Survey, vol. 16 no. 3
Type: Research Article
ISSN: 0263-080X

Keywords

Article
Publication date: 1 September 2000

Tsao‐Tsung Ma, Kwok Lun Lo and Mehmet Tumay

This paper proposes an ANN based adaptive damping control scheme for the unified power flow controller (UPFC) to damp the low frequency electromechanical power oscillations. In…

Abstract

This paper proposes an ANN based adaptive damping control scheme for the unified power flow controller (UPFC) to damp the low frequency electromechanical power oscillations. In this paper a novel damping control strategy based on the time‐domain analysis of system transient energy function (TEF) is proposed and implemented by using well tuned conventional PI controllers to obtain the preliminary training data for the design of the proposed controllers. The multi‐layered feed forward neural network with error back‐propagation training algorithm is employed in this study. Models of UPFC and ANN controllers suitable for incorporating with the transient simulation programs are derived and tested on a revised IEEE nine‐bus test system. Comprehensive simulation results demonstrate the great potential of using UPFC in damping control and the excellent performance of the proposed control scheme.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 19 no. 3
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 5 October 2021

Min Zhang, Cheng Hu, Jingwei Gao and Peng Zheng

Suspension is a significantly important component for automotive and railway vehicles. Regenerative hydraulic-electric shock absorbers (RHSA) have been proposed for the purpose of…

Abstract

Purpose

Suspension is a significantly important component for automotive and railway vehicles. Regenerative hydraulic-electric shock absorbers (RHSA) have been proposed for the purpose of attenuating vibration of vehicle suspension, and also recover kinetic energy originated from vehicle vibration that is conventionally dissipated by hydraulic dampers. To advance the technology, the paper aims to present an RHSA system for heavy-duty and railway vehicles and create a dynamic modelling to discuss on the development process of RHSA model.

Design/methodology/approach

First, the development of RHSA dynamic model can be resolved into three stage models (an ideal one, a second one with an added accumulator and a third one that considers both accumulator and system losses) to comprehensively evaluate the RHSA's characterisation. Second, a prototype is fabricated for testing and the results meet desired agreements between simulation and measurement. Finally, the study of key parameters is carried out to investigate the influences of hydraulic-cylinder size, hydraulic-motor displacement and accumulator pre-charged pressure on the RHSA system.

Findings

The findings of sensitivity analysis indicate that the component design can satisfy the damping characteristics and power performance required for heavy-duty vehicle, freight wagon and typical passenger train. The results also show that reducing the losses is highly beneficial for saving suspension energy, improving system reliability and increasing power-conversion efficiency.

Originality/value

The paper presents a more detailed method for the development and analysis of a RHSA. Compared with the typical shock absorbers, RHSA can also recover the vibration energy dissipated by suspension.

Details

Engineering Computations, vol. 39 no. 4
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 4 February 2021

Guichen Zhang, Hongtao Zhang, Heng Peng and Yinghua Liu

High-rise tower structures supported by side frame structure and viscous damper in chemical industry can produce plasticity under dynamic loads, such as wind and earthquake, which…

Abstract

Purpose

High-rise tower structures supported by side frame structure and viscous damper in chemical industry can produce plasticity under dynamic loads, such as wind and earthquake, which will heavily influence the long-term safety operation. This paper aims to systematically study the optimization design of these structures by free vibration and dynamic shakedown analysis.

Design/methodology/approach

The transfer matrix method and Euler–Bernoulli beam vibration are used to study the free vibration characteristic of the simplified high-rise tower structure. Then the extended stress compensation method is used to construct the self-equilibrated stress by using the dynamic load vertexes and the lower bound dynamic shakedown analysis for the structure with viscous damper. Using the proposed method, comprehensive parametric studies and optimization are performed to examine the shakedown load of high-rise tower with various supported conditions.

Findings

The numerical results show that the supported frame stiffness, attached damper or spring parameters influence the free vibration and shakedown characters of high-rise tower very much. The dynamic shakedown load is lowered down quickly with external load frequency increasing to the fundamental natural frequency of the structure under spring supported condition, while changed little with the damping connection. The optimized location and parameter of support are obtained under dynamical excitations.

Research limitations/implications

In this study, the high-rise tower structure is simplified as a cantilever beam supported by a short cantilever beam and a damper under repeated dynamic load, and linear elasticity for solid is assumed for free vibration analysis. The current analysis does not account for effects such as large deformation, stochastic external load and nonlinear vibration conditions which will inevitably be encountered and affect the load capacity.

Originality/value

This study provides a comprehensive method for the dynamical optimization of high-rise tower structure by combining free vibration and shakedown analysis.

Details

Engineering Computations, vol. 38 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 2 May 2017

Danguang Pan and Chenfeng Li

Extended from the classic Rayleigh damping model in structural dynamics, the Caughey damping model allows the damping ratios to be specified in multiple modes while satisfying the…

Abstract

Purpose

Extended from the classic Rayleigh damping model in structural dynamics, the Caughey damping model allows the damping ratios to be specified in multiple modes while satisfying the orthogonality conditions. Despite these desirable properties, Caughey damping suffers from a few major drawbacks: depending on the frequency distribution of the significant modes, it can be difficult to choose the reference frequencies that ensure reasonable values for all damping ratios corresponding to the significant modes; it cannot ensure all damping ratios are positive. This paper aims to present a constrained quadratic programming approach to address these issues.

Design/methodology/approach

The new method minimizes the error of the structural displacement peak based on the response spectrum theory, while all modal damping ratios are constrained to be greater than zero.

Findings

Several comprehensive examples are presented to demonstrate the accuracy and effectiveness of the proposed method, and comparisons with existing approaches are provided whenever possible.

Originality/value

The proposed method is highly efficient and allows the damping ratios to be conveniently specified for all significant modes, producing optimal damping coefficients in practical applications.

Details

Engineering Computations, vol. 34 no. 3
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 1 October 1960

D.J. Johns and P.C. Parks

The effect of structural damping on panel flutter has received little treatment in the literature but the available information suggests that such an effect may be destabilizing…

Abstract

The effect of structural damping on panel flutter has received little treatment in the literature but the available information suggests that such an effect may be destabilizing. By considering a two‐dimensional, simply‐supported panel and using linear piston theory for the aerodynamic forces an analysis is presented in which the effect of hysteretic structural damping is considered. The main emphasis is on flat unbuckled panels, although a brief investigation of buckled panels is also presented, and it is concluded that there is an interdependence of structural and aerodynamic damping, which in the range of Mach numbers for which piston theory is valid, shows the destabilizing effect of structural damping. This effect is apparently more pronounced at high altitudes. A comprehensive bibliography of panel flutter is also included.

Details

Aircraft Engineering and Aerospace Technology, vol. 32 no. 10
Type: Research Article
ISSN: 0002-2667

Article
Publication date: 1 March 1960

D.J. Mead

The theory is presented of the increase in damping that can be obtained when a damping compound is added to a simple structure vibrating in a bending mode. Consideration has been…

Abstract

The theory is presented of the increase in damping that can be obtained when a damping compound is added to a simple structure vibrating in a bending mode. Consideration has been given to the use of ‘Aquaplas’ damping compound on a vibrating stringer‐skin combination, and it has been shown that the maximum damping ratio is obtained when the material is applied to the stringer flange over the centre 40 per cent of the pin‐ended length of the beam. A preliminary experimental investigation is described, in which damping measurements were made on a simple structural specimen treated with Aquaplas. A new method was used successfully to determine the damping ratio of a heavily damped system. The damping properties of Aquaplas were evaluated, and some of the theoretical conclusions were verified. Some of the results obtained indicate that a more accurate mathematical representation must be sought for the visco‐elastic behaviour of Aquaplas than is provided by the ‘complex stiffness’ method.

Details

Aircraft Engineering and Aerospace Technology, vol. 32 no. 3
Type: Research Article
ISSN: 0002-2667

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