China
Africa
Explore chapters and articles related to this topic
Basics of Vibration and Its Isolation
Published in Ali Jamnia, Practical Guide to the Packaging of Electronics, 2016
The governing equation for a 1 DOF free vibration spring–mass system is: mx,tt+ fd+ kx = 0 where fd represents the damping force. There are two classes of damping forces: one depends on friction called Coulomb damping and the other one depends on velocity and is called viscous damping. Coulomb damping depends on surface properties and the level of applied force normal to the surface and is difficult to quantify. Viscous damping, however, is expressed as fd= cx,t Thus, the equations of motion becomes: mx,tt+cx,t+kx=0
Theory of Vibrations
Published in Swami Saran, Dynamics of Soils and Their Engineering Applications, 2021
All vibration systems offer resistance to motion due to their own inherent properties. This resistance is called damping force and it depends on the condition of vibration, material and type of the system. If the force of damping is constant, it is termed Coulomb damping. If the damping force is proportional to the velocity, it is termed viscous damping. If the damping in a system is free from its material property and is contributed by the geometry of the system, it is called geometrical or radiation damping.
Introduction to Vibrations
Published in Ramin S. Esfandiari, Bei Lu, Modeling and Analysis of Dynamic Systems, 2018
The linear viscous damping model was adopted in the previous chapters. The viscous damping force is linearly dependent on velocity, simplifying the analysis. Although this is widely used in vibration, it is not the only damping model. Coulomb damping is another type of damping in which energy is dissipated via dry friction.
Vibration control of jacket offshore wind turbine subjected to earthquake excitations by using friction damper
Published in Journal of Structural Integrity and Maintenance, 2019
Luong Minh Le, Dong Van Nguyen, Seongkyu Chang, Dookie Kim, Sung Gook Cho, Duan Duy Nguyen
Investigations on vibration control have been carried out for the offshore wind turbine (OWT). The performance of the multiple tuned mass damper in minimizing the dynamic response of the structure subjected to seismic loads combined with static wind and wave loads (Hussan, Sharmin, & Kim, 2017) have been studied. Similar to the tuned mass damper, the friction damper has its ability to reduce the vibration of the structure. Friction dampers (Noshahr et al., 2015) are installed in a structure system to activate the Coulomb damping. The damping is generated when the friction mechanism is developed due to the attainment of slip forces under lateral deformations (Ramirez et al., 2012). Pall (1979) and Pall and Marsh (1981) conducted pioneering work on friction devices which are designed to dissipate energy through the relative sliding of plates clamped by post-tensioned bolts. There have been some studies applying the friction damper for vibration control of offshore platforms (Komachi, Tabeshpour, Golafshani, & Mualla, 2011; Patil et al., 2005). In this study, we present a control method using diagonal-bracing friction damper system for NREL 5-MW OWT (Jonkman, Butterfield, Musial, & Scott, 2009). For earthquake analyses, OpenSees has been proved as one of the most effective software (Mazzoni, McKenna, Scott, & Fenves, 2007, Tran, Nguyen, & Kim, 2018; Ryan, Broderick, Hunt, Goggins, & Salawdeh, 2017). For that reason, in this study, OpenSees is used to simulate two steel structures of the wind turbine as steel structures without and with friction dampers. Then, dynamic nonlinear analysis (Baratia et al., 2012 and Kim, Wang, & Chaudhary, 2016) is conducted.