000000968 001__ 968
000000968 005__ 20141118153509.0
000000968 04107 $$acze
000000968 046__ $$k2002-05-13
000000968 100__ $$aZapoměl, Jaroslav
000000968 24500 $$aSTABILITY INVESTIGATION OF ROTORS EXCITED BY UNBALANCE OF THE ROTATING PARTS AND SUPPORTED BY SHORT NON-CIRCULAR FLUID FILM BEARINGS
000000968 24630 $$n8.$$pEngineering Mechanics 2002
000000968 260__ $$bInstitute of Mechanics and Solids, FME, TU Brno
000000968 506__ $$arestricted
000000968 520__ $$2cze$$aAbstrakt: Properties of fluid film bearings are significantly influenced by the shape of the cross section of the holes in the bearing shells. In computational models they are usually incorporated by means of nonlinear force couplings. To determine components of the hydraulical forces it is necessary to solve a Reynolds' equation to obtain a pressure function that describes a pressure distribution in the oil layer. In the case of short bearings the pressure function can be expressed in a closed form. If at some location in the bearing gap the pressure drops below a certain limit, a cavitation takes place. Accommodation of this phenomenon in the computational procedure assumes that pressure of the medium in cavitated areas remains approximately constant.  Components of the bearing forces are then calculated by means of integration of the pressure distribution around the circumference of the bearings. The considered model rotor systems are able to cover all significant properties of the real ones. Their steady state response on excitation produced by centrifugal forces due to unbalance of the rotating parts can be determined for a certain class of problems by application of a trigonometric collocation method. To perform stability and bifurcation analysis a perturbation technique based on utilization of a Floquet theory has been used. Principal steps of this procedure consist in setting up a transition matrix over the span of time of one period and in calculation of its eigenvalues.
000000968 520__ $$2eng$$aAbstract: Properties of fluid film bearings are significantly influenced by the shape of the cross section of the holes in the bearing shells. In computational models they are usually incorporated by means of nonlinear force couplings. To determine components of the hydraulical forces it is necessary to solve a Reynolds' equation to obtain a pressure function that describes a pressure distribution in the oil layer. In the case of short bearings the pressure function can be expressed in a closed form. If at some location in the bearing gap the pressure drops below a certain limit, a cavitation takes place. Accommodation of this phenomenon in the computational procedure assumes that pressure of the medium in cavitated areas remains approximately constant.  Components of the bearing forces are then calculated by means of integration of the pressure distribution around the circumference of the bearings. The considered model rotor systems are able to cover all significant properties of the real ones. Their steady state response on excitation produced by centrifugal forces due to unbalance of the rotating parts can be determined for a certain class of problems by application of a trigonometric collocation method. To perform stability and bifurcation analysis a perturbation technique based on utilization of a Floquet theory has been used. Principal steps of this procedure consist in setting up a transition matrix over the span of time of one period and in calculation of its eigenvalues.
000000968 540__ $$aText je chráněný podle autorského zákona č. 121/2000 Sb.
000000968 7112_ $$aEngineering Mechanics 2002$$cSvratka (CZ)$$d2002-05-13 / 2002-05-16$$gEM2002
000000968 720__ $$aZapoměl, Jaroslav
000000968 8560_ $$ffischerc@itam.cas.cz
000000968 8564_ $$s223336$$uhttps://invenio.itam.cas.cz/record/968/files/Zapomel_1.pdf$$y
             Original version of the author's contribution as presented on CD, .
            
000000968 962__ $$r451
000000968 980__ $$aPAPER