Calculations and Experiments on the Unbalance Response of a Flexible Rotor

Abstract

The results of a combined analytical and experimental investigation of the unbalance vibrations of a rotor are presented. The analysis applies to a general rotor-bearing system in which the dynamic bearing forces are represented by four spring coefficients and four damping coefficients. The rotor can be represented as either a lumped or a distributed parameter system, and gyroscopic moments are included. In general, the unbalance whirl motion of the rotor will be elliptical. The analysis has been programmed for a digital computer to obtain results for comparison with the experimental data. The test rotor is a uniform, flexible shaft with heavy wheels mounted at the ends and in the middle. The rotor is supported in two silicone fluid-lubricated, tilting-pad bearings. The rotor amplitude caused by an induced unbalance has been measured over a speed range of 3000 to 24,000 rpm for three different rotor configurations, obtained by removing one or both end wheels. This speed range extends to or through the third critical speed for each of the rotor configurations. The results are compared with the theoretical values and, in general, the agreement is found to be good.

Finite Element Modeling of a Rotor Shaft Rolling Bearings System With Consideration of Bearing Nonlinearities

“…Currently, two main numerical procedures are employed in the area of rotating machinery analysis-namely, the transfer matrix (Lund and Orcutt, 1967) and the finite element method (Ruhl and Booker, 1972). Compared to the transfer matrix, the finite element method has the advantage of accurately modeling rotor bearing systems with a fewer number of elements while being less sensitive to numerical instabilities, although sometimes it requires more CPU time and computer storage (Ruhl and Booker, 1972).…”

Vibrations of a Rotor System With Multiple Coupler Offsets

“…Lund and Orcutt [6] improved the transfer matrix of a shaft in a continuous fashion rather than in a discrete fashion, but neglected both rotary inertia and the gyroscopic effect. Lund [7] considered the hysteretic of a damping shaft and calculated the unbalanced response of a general flexible rotor supported in a fluid-film journal bearing.…”

Active Balancing and Vibration Control of Rotating Machinery: A Survey

“…It was first used in the area of torsional vibrations. In the early 1970s, Lund (1967Lund ( , 1974aLund ( , 1974b presented procedures that used this method for rotor dynamic analysis. The advantage of the transfer matrix method is that it does not require the storage and manipulation of large system arrays.…”