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Gewei Z.,Trinity College Dublin | Gewei Z.,Wuhan Ship Development and Design Institute | Basu B.,Trinity College Dublin
JVC/Journal of Vibration and Control | Year: 2011

Tuned mass dampers (TMDs) have been a popular vibration control device used primarily for suppressing wind-induced oscillations in tall structures and have recently also been used for controlling vibrations due to seismic excitations. A nonlinear damper consisting of a TMD with a nonlinear dry (pure) friction damping at the interface between the primary structure and the TMD is analyzed in this paper. This nonlinear damper has potential for control of vibration but has not received much attention by researchers. In particular, the nonlinear behavior of the system has not been explored in detail so far. A periodic solution for the response of the structure-friction TMD (FTMD) system modeled as a two-degree-of-freedom system is obtained under harmonic excitation using harmonic balance based on a method of averaging. To consider more realistic random excitations, a statistical linearization method is used to replace the nonlinear friction by an equivalent viscous damping. Numerical simulations have demonstrated that the linearized solutions for both the harmonic and the random cases are accurate enough. The periodic and statistical linearized solutions are used to analyze dynamic characteristics of structure-FTMD system. As expected in a nonlinear system, the frequency response function (FRF) of the displacement response of the structure for the structure-FTMD system is dependent on the level of excitation. For a given level of excitation, an optimum friction coefficient has been found to exist which corresponds to the least root-mean-square value of the displacement response of the primary mass. © The Author(s) 2010.

Xu H.,Wuhan Ship Development and Design Institute | Chen L.,Wuhan Ship Development and Design Institute | Qin J.,Wuhan University of Technology
Wuhan Ligong Daxue Xuebao (Jiaotong Kexue Yu Gongcheng Ban)/Journal of Wuhan University of Technology (Transportation Science and Engineering) | Year: 2013

Contraposing three combinations of fims and bilge keels (continuous bilge keels and two pairs of fixed fims, continuous bilge keels and a pair of fixed fims in front of them, discontinuous bilge keels and a pair of fixed fims in middle of them), the speeding of ship is compared by CFD method and model test. Moreover when the fims in after two combinations are extension ones and entireiy in ship in unworking condition, the resistance and speed in calm water are analysed. Therefore the influence on speeding in different combinations of fims and bilge keels is gained and the relevant conclusion can be used in ship design and speeding optimization.

Yu L.,China Ship Development And Design Center | Liu S.,Wuhan Ship Development and Design Institute | Ye L.,Sichuan University | Huang G.,Sichuan University | Xu Y.,Sichuan University
Journal Wuhan University of Technology, Materials Science Edition | Year: 2012

The dynamic stiffness and the specific damping energy, as well as the vibration response characteristics of a silicone rubber isolator were researched. The results of the vibration test showed that the silicone rubber isolator was excellent in the performance of vibration control. The dynamic stiffness and the damping characteristics were non-linear. From the comparison between experimental results and simulation analysis, the displacement transmissibility characteristics of the isolator were obtained. As a result, the dynamic characteristics of the isolator could be accurately described by the quadratic type non-linear terms at small amplitude. ©Wuhan University of Technology and SpringerVerlag Berlin Heidelberg 2012.

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