Limit cycle oscillations at resonances

1st Conference of Computational Methods in Offshore Technology

计算机科学

Hellevik, K.^1 ; Gudmestad, O.T.^1

Department of Mechanical and Structural Engineering and Material Science, University of Stavanger, Stavanger

4036, Norway^1

关键词: Degree of freedom;    Displacement velocity;    Higher order resonances;    Limit Cycle Oscillation (LCO);    Nonlinear loading;    Oscillatory flows;    Self excited oscillation;    Van der pol equation;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/276/1/012020/pdf
DOI  :  10.1088/1757-899X/276/1/012020

学科分类：计算机科学（综合）

来源: IOP

【 摘 要 】

This paper deals with limit cycles in one degree of freedom systems. The van der Pol equation is an example of an equation describing systems with clear limit cycles in the phase space (displacement-velocity 2 dimensional plane). In this paper, it is shown that a system with nonlinear loading, representing the drag load acting on structures in an oscillatory flow (the drag term of the Morison equation), will in fact exhibit limit cycles at resonance and at higher order resonances. These limit cycles are stable, and model self-excited oscillations. As the damping in the systems is linear and constant, the drag loading will to some degree work as negative damping. The consequences of the existence of these limit cycles are that systems starting at lesser amplitudes in the phase plane will exhibit increased amplitudes until the limit cycle is obtained.