Vibration Mode Structure of Cyclically Symmetric Centrifugal Pendulum Vibration Absorber Systems

2012 ◽  
Author(s):  
Chengzhi Shi ◽  
Robert G. Parker
Keyword(s):  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Vibration Modes ◽  
Rotational Degree ◽  
Cyclic Symmetry ◽  
Mode Structure ◽  
Vibration Properties ◽  
Centrifugal Pendulum Vibration Absorber ◽  
Gyroscopic Effects ◽  
Modal Vibration

This work develops an analytical model of centrifugal pendulum vibration absorber systems with equally-spaced, identical absorbers and uses it to investigate the structure of the modal vibration properties. The planar model admits two translational and one rotational degree-of-freedom for the rotor and a single arclength degree-of-freedom for each absorber. The gyroscopic effects from rotor rotation are taken into account. Examination of the associated eigenvalue problem reveals well-defined structure of the vibration modes resulting from the cyclic symmetry of the absorbers. The vibration modes are classified into rotational, translational, and absorber modes. Characteristics of each mode type are analytically proved.

Vibration Modes and Natural Frequency Veering in Three-Dimensional, Cyclically Symmetric Centrifugal Pendulum Vibration Absorber Systems

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Chengzhi Shi ◽  
Robert G. Parker
Keyword(s):  
Degrees Of Freedom ◽  
Vibration Mode ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Vibration Absorber ◽  
Vibration Modes ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Mode Structure ◽  
Centrifugal Pendulum Vibration Absorber

This paper investigates the vibration mode structure of three-dimensional, cyclically symmetric centrifugal pendulum vibration absorber (CPVA) systems. The rotor in the system has two translational, one rotational, and two tilting degrees of freedom. The equations of motion for the three-dimensional model, including the rotor tilting, are derived to study the modes analytically and numerically. Only three mode types exist: rotational, translational-tilting, and absorber modes. The rotational and absorber modes have identical properties to those of in-plane models. Only the translational-tilting modes contain rotor tilting. The veering/crossing behavior between the eigenvalue loci is derived analytically.

Dynamic Modeling of Multi-Stage Planetary Gears Coupled with Bearings in Housing

2011 ◽  
Vol 86 ◽  
pp. 30-34
Author(s):  
Zheng Ming Xiao ◽  
Da Tong Qin
Keyword(s):  
Planetary Gear ◽  
Degree Of Freedom ◽  
Design Parameters ◽  
Parameter Method ◽  
Rotational Degree ◽  
Planetary Gears ◽  
Multi Stage ◽  
Lumped Parameter ◽  
Shield Tunnelling ◽  
Gyroscopic Effects

This work develops an analytical model of multi-stages planetary gear transmission (PGT) coupled with bearings in housing based on analyzing the displacement relationships of gearing system. The model adopts three planar degree-of-freedom for each of the central components, and the rotational degree-of-freedom for the planets of each stage. Considering the gyroscopic effects, the modified transverse-torsional model is established in the rotating Cartesian coordinates by lumped-parameter method, which is more accurate and may match with the physical model better than the purely torsional model. According to the design parameters of the 3-stage planetary gears of main reducer of shield tunnelling machine, the natural frequencies and vibration modes are investigated by using this transverse-torsional model.

Identification of Equivalent Modal Damping and Frequencies in Multi Degree-of-Freedom Nonlinear Systems

2011 ◽  
Author(s):  
D. Dane Quinn ◽  
Richard J. Ott ◽  
Sean Hubbard ◽  
D. Michael McFarland ◽  
Lawrence A. Bergman ◽  
...  
Keyword(s):  
Nonlinear Systems ◽  
Time History ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
Primary System ◽  
Vibration Modes ◽  
Structural System ◽  
Modal Damping ◽  
History Of ◽  
Two Degree Of Freedom

We consider the response of a linear structural system when coupled to an attachment containing strong or even essential nonlinearities. For this system, the attachment is designed as a nonlinear vibration absorber, serving to dissipate energy from the structural system. Moreover, the attachment not only leads to a reduction in the total energy of the system, but also couples together the vibration modes of the linear structural system, thereby allowing for energy to also be redistributed among these structural modes of the system. The effect of the nonlinear attachment on the linear primary system can be quantified in terms of equivalent measures for the damping and frequency of each mode, derived through consideration of the energy in each mode. The identification of these equivalent measures is illustrated on a two degree-of-freedom primary system. Moreover, this procedure depends only on the time history of the response and is therefore suited to both simulation and experimental results.

scholarly journals Vibration of Rotating and Revolving Planet Rings with Discrete and Partially Distributed Stiffnesses

2020 ◽  
Vol 11 (1) ◽  
pp. 127
Author(s):  
Fuchun Yang ◽  
Dianrui Wang
Keyword(s):  
High Speed ◽  
Differential Operators ◽  
Natural Frequencies ◽  
Rotation Speed ◽  
Distribution Area ◽  
Vibration Modes ◽  
Governing Equations ◽  
Vibration Properties ◽  
Wide Range ◽  
Forced Responses

Vibration properties of high-speed rotating and revolving planet rings with discrete and partially distributed stiffnesses were studied. The governing equations were obtained by Hamilton’s principle based on a rotating frame on the ring. The governing equations were cast in matrix differential operators and discretized, using Galerkin’s method. The eigenvalue problem was dealt with state space matrix, and the natural frequencies and vibration modes were computed in a wide range of rotation speed. The properties of natural frequencies and vibration modes with rotation speed were studied for free planet rings and planet rings with discrete and partially distributed stiffnesses. The influences of several parameters on the vibration properties of planet rings were also investigated. Finally, the forced responses of planet rings resulted from the excitation of rotating and revolving movement were studied. The results show that the revolving movement not only affects the free vibration of planet rings but results in excitation to the rings. Partially distributed stiffness changes the vibration modes heavily compared to the free planet ring. Each vibration mode comprises several nodal diameter components instead of a single component for a free planet ring. The distribution area and the number of partially distributed stiffnesses mainly affect the high-order frequencies. The forced responses caused by revolving movement are nonlinear and vary with a quasi-period of rotating speed, and the responses in the regions supported by partially distributed stiffnesses are suppressed.

Anomalous metallic-like transport of Co–Pd ferromagnetic nanoparticles cross-linked with π-conjugated molecules having a rotational degree of freedom

2014 ◽  
Vol 16 (1) ◽  
pp. 288-296 ◽  
Author(s):  
Yoshikazu Ito ◽  
Kazuyuki Takai ◽  
Akira Miyazaki ◽  
Vajiravelu Sivamurugan ◽  
Manabu Kiguchi ◽  
...  
Keyword(s):  
Degree Of Freedom ◽  
Ferromagnetic Nanoparticles ◽  
Rotational Degree ◽  
Conjugated Molecules

scholarly journals Study on Multi-Degree of Freedom Dynamic Vibration Absorber of the Carbody of High-Speed Trains

2021 ◽  
Author(s):  
Yu SUN ◽  
Jinsong Zhou ◽  
Dao Gong ◽  
Yuanjin Ji
Keyword(s):  
Vibration Control ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
High Speed Train ◽  
Dynamic Vibration Absorber ◽  
Multiple Degrees Of Freedom ◽  
Dynamic Vibration

Abstract To absorb the vibration of the carbody of the high-speed train in multiple degrees of freedom, a multi-degree of freedom dynamic vibration absorber (MDOF DVA) is proposed. Installed under the carbody, the natural vibration frequency of the MDOF DVA from each DOF can be designed as a DVA for each single degree of freedom of the carbody. Hence, a 12-DOF model including the main vibration system and a MDOF DVA is established, and the principle of Multi-DOF dynamic vibration absorption is analyzed by combining the design method of single DVA and genetic algorithm. Based on a high-speed train dynamics model including an under-carbody MDOF DVA, the vibration control effect on each DOF of the MDOF DVA is analyzed by the virtual excitation method. Moreover, a high static and low dynamic stiffness (HSLDS) mount is proposed based on a cam–roller–spring mechanism for the installation of the MDOF DVA due to the requirement of the low vertical dynamic stiffness. From the dynamic simulation of a non-linear model in time-domain, the vibration control performance of the MDOF DVA installed with nonlinear HSLDS mount on the carbody is analyzed. The results show that the MDOF DVA can absorb the vibration of the carbody in multiple degrees of freedom effectively, and improve the running ride quality of the vehicle.

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