Non-autonomous Two-Degree-of-Freedom Cubic Systems with Close Natural Frequencies

2005 ◽  
pp. 77-133
Keyword(s):  
Natural Frequencies ◽  
Degree Of Freedom ◽  
Cubic Systems ◽  
Two Degree Of Freedom

Technical Note: A two-degree-of-freedom ambulance stretcher suspension: Part 3: Laboratory and road test performance

1998 ◽  
Vol 212 (5) ◽  
pp. 401-407 ◽  
Author(s):  
R. J. Henderson ◽  
J. K. Raine
Keyword(s):  
Test Performance ◽  
Natural Frequencies ◽  
Low Cost ◽  
Mechanical Systems ◽  
Technical Note ◽  
Suspension System ◽  
Degree Of Freedom ◽  
Road Test ◽  
Pneumatic Suspension ◽  
Two Degree Of Freedom

Parts 1 and 2 of this paper gave a design overview and described the dynamics of a prototype two-degree-of-freedom pneumatic suspension for an ambulance stretcher. This concluding part briefly reviews laboratory shaker table and ambulance road test performance of the suspension with passive pneumatic damping. The suspension system is found to offer compact low-cost isolation with lower natural frequencies than achieved in earlier mechanical systems.

The Galloping Response of a Two-Degree-of-Freedom System

1974 ◽  
Vol 41 (4) ◽  
pp. 1113-1118 ◽  
Author(s):  
R. D. Blevins ◽  
W. D. Iwan
Keyword(s):  
Steady State ◽  
Closed Form ◽  
Natural Frequencies ◽  
Analytic Solutions ◽  
Degree Of Freedom ◽  
Approximate Analysis ◽  
Stability Criteria ◽  
Integer Multiple ◽  
Two Degree Of Freedom ◽  
Steady State Solutions

The galloping response of a two-degree-of-freedom system is investigated using asymptotic techniques to generate approximate steady-state solutions. Simple closed-form analytic solutions and stability criteria are presented for the case where the two structural natural frequencies are harmonically separated. Examples of the nature of the galloping response of a particular section are presented for the case where the frequencies are harmonically separated as well as for the case where the two natural frequencies are near an integer multiple of each other. The results of the approximate analysis are compared with experimental and numerical results.

Experimental Determination of the Complete Dynamical Properties of a Two-Degree-Of-Freedom Model Having Nearly Coincident Natural Frequencies

1967 ◽  
Vol 9 (5) ◽  
pp. 402-413 ◽  
Author(s):  
R. W. Traill-Nash ◽  
G. Long ◽  
C. M. Bailey
Keyword(s):  
Experimental Investigation ◽  
Experimental Determination ◽  
Natural Frequencies ◽  
Degree Of Freedom ◽  
Influence Coefficients ◽  
Stiffness Properties ◽  
Modes Of Vibration ◽  
Dynamical Properties ◽  
Two Degree Of Freedom

Existing techniques of resonance testing have shown a marked inability to find the principal modes, natural frequencies and levels of damping in a structure which possesses two or more close natural frequencies (1)§. This paper describes an experimental investigation on a two-degree-of-freedom model of a technique which makes use of dynamical influence coefficients (or receptances) measured at a number of stations on the structure (2) (3) (4) (5). The measured coefficients are used to calculate natural frequencies and modes of vibration, and the mass, damping and stiffness properties of the system. Several model configurations having different natural frequency separations were tested and no special difficulty resulted when natural frequencies were close or even coincident.

Hydrodynamics Loads on Two Degree-of-Freedom Cylinder With Uncertain Natural Frequencies Subject to VIV

2009 ◽  
Author(s):  
Didier Lucor
Keyword(s):  
Natural Frequencies ◽  
Numerical Study ◽  
Spectral Element ◽  
Numerical Approach ◽  
Response Surfaces ◽  
Degree Of Freedom ◽  
Two Dimensional ◽  
Wide Range ◽  
Two Dimensional Flow ◽  
Two Degree Of Freedom

In this numerical study, we build response surfaces of two degree-of-freedom vortex-induced vibrations (VIV) of flexibly mounted cylinders for a wide range of transverse and in-line natural frequencies. We consider both the structure and the flow to be two-dimensional and the structure has a low mass damping. The emphasis is put on the representation of the hydrodynamic loads acting on the cylinder in response to the change in the natural frequencies of the structure. The system is sampled for a wide range of natural frequencies within the synchronization region, totaling 149 two-dimensional flow-structure simulations. The parametric range of the in-line frequency is chosen to be larger than the one of the transverse frequency in order to favor multi-modal responses. No preferred frequencies are emphasized within the intervals of study. The fully spectral numerical approach relies on a stochastic collocation method coupled to a spectral element-based deterministic solver.

scholarly journals Parametrically Excited Nonlinear Two-Degree-of-Freedom Systems With Repeated Natural Frequencies

1993 ◽  
Author(s):  
A. H. Nayfeh ◽  
C. Chin ◽  
D. T. Mook
Keyword(s):  
Parametric Excitation ◽  
Nonlinear Response ◽  
Normal Forms ◽  
Natural Frequencies ◽  
Linear Part ◽  
Degree Of Freedom ◽  
Cubic Nonlinearity ◽  
Simply Supported ◽  
The Stability ◽  
Two Degree Of Freedom

Abstract The method of normal forms is used to study the nonlinear response of two-degree-of-freedom systems with repeated natural frequencies and cubic nonlinearity to a principal parametric excitation. The linear part of the system has a nonsemisimple one-to-one resonance. The character of the stability and various types of bifurcation are analyzed. The results are applied to the flutter of a simply-supported panel in a supersonic airstream.

Sign in / Sign up

Export Citation Format

Share Document