Nonlinear dynamic analysis of multiple grooved water-lubricated journal bearings using attenuation rate interpolation method

Purpose The stringent requirements for environmental protection have induced the extensive applications of water-lubricated journal bearings in marine propulsion. The nonlinear dynamic analysis of multiple grooved water-lubricated bearings (MGWJBs) has not been fully covered so far in the literature. This study aims to conduct the nonlinear dynamic analysis of the instability for MGWJBs. Design/methodology/approach An attenuation rate interpolation method is proposed for the determination of the critical instability speed. Based on a structured mesh movement algorithm, the transient hydrodynamic force model of MGWJBs is set up. Furthermore, the parameters’ analysis of nonlinear instability for MGWJBs is conducted. The minimum water film thickness, side leakage, friction torque and power loss of friction are fully analyzed. Findings With the increase of speed, the journal orbits come across the steady state equilibrium motion, sub-harmonic motion and limit circle motion successively. At the limit circle motion stage, the orbits are much larger than that of steady state equilibrium and sub-harmonic motion. The critical instability speed increases when the spiral angle decreases or the groove angle increases. The minimum water film thickness peak is at the rotor speed of 4,000 r/min for the MGWJB with Sa = 0°. As rotor speed increases, the side leakage decreases slightly while the friction torque and the power loss of friction increase gradually. Originality/value Present research provides a beneficial reference for the dynamic mechanism analysis and design of MGWJBs.

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Seismic damage evaluation of reinforced concrete buildings with slit walls

Engineering Computations ◽

10.1108/ec-09-2014-0197 ◽

2015 ◽

Vol 32 (6) ◽

pp. 1661-1690 ◽

Cited By ~ 2

Author(s):

Sergiu Andrei Baetu ◽

Alex H Barbat ◽

Ioan Petru Ciongradi ◽

Georgeta Baetu

Keyword(s):

Reinforced Concrete ◽

Dynamic Analysis ◽

Computational Model ◽

Nonlinear Dynamic ◽

Seismic Analysis ◽

Nonlinear Dynamic Analysis ◽

Structural Walls ◽

Content Type ◽

Solid Walls ◽

Storey Building

Purpose – The purpose of this paper is to investigate a reinforced concrete multi-storey building with dissipative structural walls. These walls can improve the behaviour of a tall multi-storey building. The authors’ main objective is to evaluate the damage of a building with dissipative walls in comparison with that of a building with solid walls. Design/methodology/approach – In this paper, a comparative nonlinear dynamic analysis between a building with slit walls and then the same building with solid walls is performed by means of SAP2000 software and using a layer model. The solution to increase the seismic performance of a building with structural walls is to create slit zones with short connections in to the walls. The short connections are introduced as a link element with multi-linear pivot hysteretic plasticity behaviour. The hysteretic rules and parameters of these short connections were proposed by the authors and used in this analysis. In this study, the authors propose to evaluate the damage of a building with reinforced concrete slit walls with short connections using seismic analysis. Findings – Using the computational model created by the authors for the slit wall, a seismic analysis of a multi-storey building with slit walls was done. From the results obtained, the advantages of the proposed model are observed. Originality/value – Using a simple computational model, created by the authors, that consume low processing resources and reduces processing time, a nonlinear dynamic analysis on high-rise buildings was done. Unlike other studies on slit walls with short connections, which are focused mostly on the nonlinear dynamic behaviour of the short connections, in this paper the authors take into consideration the whole structural system, wall, connections and frames.

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