Investigation of Anisotropic Rotor with Different Shaft Orientation.
Technische Universität, Darmstadt
[Ph.D. Thesis], (2009)
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|Item Type:||Ph.D. Thesis|
|Title:||Investigation of Anisotropic Rotor with Different Shaft Orientation|
The present work deals with a new discrete model of an anisotropic rotor. The rotor is supported by rigid or anisotropic flexible bearings. Because of different orientations of the cross-section along the shaft, the rotor is modelled by discrete elements. An anisotropic rotor system can be analyzed both in a fixed and in a rotating reference frames. In fixed reference frame, the shaft stiffness varies with time. In rotating reference frame, the differential equations of the system become speed-dependent. If an anisotropic rotor is supported by anisotropic flexible bearings, the system stiffness is always a time-variant parameter whether the rotor is modelled in a fixed or in a rotating reference frame. In the developed model, the shaft stiffness matrix is assembled in the rotating reference frame by considering asymmetric bending by means of the strain energy method. The gyroscopic moments and the internal and external damping are taken into account. The differential equations of motion of the rotor are developed for a rotor at constant angular speed, at constant angular acceleration and accelerated by a constant driving torque. A stability investigation is conducted of an anisotropic rotor through analysis of eigenvalues for a speed-dependent rotor system and by using Floquet theory for a time-variant rotor system. The dynamic responses of the rotor are solved by using the Runge-Kutta method of fourth order. Several anisotropic rotors with single or two disks with different shaft orientations are presented. Additionally, an approach of a twisted anisotropic rotor is developed and analyzed with the minimum and a high number of discrete shaft elements. The eigenvalue analyses and stability charts of these models are presented. The influences of the shaft element anisotropy and the difference in the shaft orientation are analyzed. The difference in the shaft orientation affects the occurrence of the second region of instability and the width of instability. The occurrence of gyroscopic moments in the rotor system is influenced not only by the asymmetry of the rotor but also by the difference in the shaft orientation. Experimental investigation of an anisotropic rotor with two disks and different shaft orientations is conducted at constant angular speed and constant angular acceleration. These experimental results are benchmarked with the numerical simulations of the developed discretized model.
|Place of Publication:||Darmstadt|
|Uncontrolled Keywords:||Anisotropic rotor, shaft orientation, stability|
|Classification DDC:||600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften|
|Divisions:||16 Department of Mechanical Engineering > Institute of Applied Dynamics (AD)|
|Date Deposited:||28 May 2009 06:08|
|Last Modified:||07 Dec 2012 11:55|
|Referees:||Markert, Prof. Dr.- Richard and Hagedorn, Prof. Dr. Peter|
|Refereed:||13 May 2009|