Dynamic behavior of pipelines and risers due to vortex-induced vibration in time domain

2011 ◽  
Vol 6 (1) ◽  
pp. 17-26 ◽  
Author(s):  
Celso K. Morooka ◽  
Raphael I. Tsukada
Keyword(s):  
Dynamic Behavior ◽  
Time Domain ◽  
Vortex Induced Vibration

Modeling and Dynamic Behavior of Battery Energy Storage: A Simple Model for Large-Scale Time-Domain Stability Studies

2015 ◽  
Vol 3 (3) ◽  
pp. 47-51 ◽  
Author(s):  
Pouyan Pourbeik ◽  
Stephen E. Williams ◽  
James Weber ◽  
Juan Sanchez-Gasca ◽  
Jay Senthil ◽  
...  
Keyword(s):  
Energy Storage ◽  
Simple Model ◽  
Dynamic Behavior ◽  
Time Domain ◽  
Large Scale ◽  
Stability Studies ◽  
Battery Energy Storage ◽  
Battery Energy ◽  
Domain Stability

Coupled Analysis of Deepwater Floating System Including VIV in Time Domain

2007 ◽  
Author(s):  
Jun-Bumn Rho ◽  
Alexander A. Korobkin ◽  
Jong-Jun Jung ◽  
Hyun-Soo Shin ◽  
Woo-Seob Lee
Keyword(s):  
Finite Element ◽  
Time Domain ◽  
Torsional Stiffness ◽  
Time Step ◽  
Vortex Induced Vibration ◽  
Coupled Equations ◽  
Floating System ◽  
Vessel Motion ◽  
Floating Systems ◽  
The Way

Deepwater floating systems consist of a vessel, risers, and mooring lines. To accurately simulate the floating systems in current, wind, and waves considering (1) bending and torsional stiffness of riser, (2) elongation of the mooring/riser elements, (3) complex end conditions, (4) internal flow effects, and (5) vortex induced vibration, it is necessary to evaluate the vessel motions and mooring/riser behaviors simultaneously in time domain. However, because the size of the system matrix increases significantly as the number of mooring/riser increases, it is quite time-consuming to solve all equations including both mooring/riser and vessel dynamics simultaneously. The present study was performed in order to develop a program for this problem. The 6DOF vessel dynamics is described by the Cummins equation. And the mooring and riser are modeled with the help of finite-element beam. The Newmark method is used as the time marching scheme of the FEM equations for each mooring/riser and the vessel. The coupled equations of the mooring/riser segments and vessel are solved alternatively at each time step. Mooring/riser and the vessel motion affect to each other in the way that the components of the forces at the segment ends are determined as functions of displacements and slopes of them. This procedure makes it possible to consider the coupling effects between vessel and mooring/riser efficiently. Also no iterations are required to match the vessel motion with the riser dynamics. This new approach allows us to use parallel computations and to deal with as many mooring/riser at the same time as necessary. The hydrodynamic forces induced by current are calculated by using the Morison’s formula. The VIV (Vortex Induced Vibration) effects are included in the way that the frequency and the shape of the riser vibration due to VIV are pre-calculated by iterations in the frequency domain. Then the finite element mooring/riser model is modified to consider the hydrodynamic loads including VIV and integrated in the final equations of the floating system in time domain.

scholarly journals Normalized Study of Three-Parameter System in the Time Domain and Frequency Domain

2017 ◽  
Vol 2017 ◽  
pp. 1-21
Author(s):  
Xiao-Lei Jiao ◽  
Yang Zhao ◽  
Wen-Lai Ma
Keyword(s):  
Frequency Domain ◽  
Dynamic Behavior ◽  
Time Domain ◽  
Phase Margin ◽  
Stiffness Ratio ◽  
Parameter System ◽  
Regulatory Factor ◽  
First Case ◽  
The Time Domain ◽  
Isolation Performance

Three-parameter isolation system can be used to isolate microvibration for control moment gyroscopes. Normalized analytical model for three-parameter system in the time domain and frequency domain is proposed by using analytical method. Dynamic behavior of three-parameter system in the time domain and frequency domain is studied. Response in the time domain under different types of excitations is analyzed. In this paper, a regulatory factor is defined in order to analyze dynamic behavior in the frequency domain. For harmonic excitation, a comparison study is made on isolation performance between the case when the system has optimal damping and the case when regulatory factor is 1. Besides, phase margin of three-parameter system is obtained. Results show that dynamic behavior in the time domain and frequency domain changes with regulatory factor. Phase margin has the largest value when the value of regulatory factor is 1. System under impulse excitation and step excitation has the shortest settling time for the response in the time domain when the value of regulatory factor is 1. When stiffness ratio is small, isolation performances of two cases are nearly the same; when system has a large stiffness ratio, isolation performance of the first case is better.

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