Showing papers on "Rotary inertia published in 1984"

Vertical Vibration in Timoshenko Beam Suspension Bridges

Abstract: A method of analysis is presented for free vertical vibration of suspension bridges. The method takes into account the effects of shear deformation and rotary inertia, and uses a linearized theory which maintains small amplitudes of vibration. The formulation of the problem is based on the Timoshenko beam theory, and the differential equations of motion and the associated boundary conditions are derived by applying Hamilton's principle. The analysis is conducted by using general solutions for the fourth order differential equation of motion. The objective of the study is to determine a sufficient number of natural frequencies and mode shapes, and to enable an accurate vibration analysis for higher modes. A detailed numerical example, which includes the various boundary conditions of the stiffening girders and the elasticity of the towers, is shown to illustrate the applicability of the analysis and to investigate the dynamic characteristics of vertical vibrating suspension bridges.

Measurements of Squeeze Film Bearing Forces to Demonstrate the Effect of Fluid Inertia

Abstract: Squeeze film dampers are commonly applied to high speed rotating machinery, such as aircraft engines, to reduce vibration problems. The theory of hydrodynamic lubrication has been used for the design and modeling of dampers in rotor dynamic systems despite typical modified Reynolds numbers in applications between ten and fifty. Lubrication theory is strictly valid for Reynolds numbers much less than one, which means that fluid viscous forces are much greater than inertia forces. Theoretical papers which account for fluid inertia in squeeze films have predicted large discrepancies from lubrication theory, but these results have not found wide acceptance by workers in the gas turbine industry. Recently, experimental results on the behavior of rotor dynamic systems have been reported which strongly support the existence of large fluid inertia forces. In the present paper direct measurements of damper forces are presented for the first time. Reynolds numbers up to ten are obtained at eccentricity ratios 0.2 and 0.5. Lubrication theory underpredicts the measured forces by up to a factor of two (100% error). Qualitative agreement is found with predictions of earlier improved theories which include fluid inertia forces.Copyright © 1984 by ASME

Device for compensating jolts in the rotational movement of an engine

Abstract: The invention relates to a device for compensating jolts in the rotational movement of an engine 5, especially during changes in torque, by means of two inertia masses 3, 4 arranged coaxially with respect to one another and capable of revolving relatively in opposition to the action of a damping device and one of which is connected to the internal combustion engine and the other to the input part 10 of a transmission. The damping device is arranged so as to produce variable damping by means of the relative rotation of the two inertia masses 3, 4; an additional frictional damping element may be used or the inertia masses 3, 4 may be mounted so as to carry out a limited relative axial movement as a function of the actuation of a friction clutch 7.

Free vibration analysis of rectangular plates with cutouts allowing for transverse shear deformation and rotary inertia

Abstract: The energy approach using the variational procedure in conjunction with the finite difference technique has been applied for the Mindlin theory dynamic analysis of rectangular plates with cutouts in which account is taken of the effects of both transverse shear deformation and rotary inertia. This study has clearly demonstrated that the discrepancy with the thin plate theory solutions increases with increasing values of thickness ratio β and the error due to the thin plate assumptions increases particularly for the higher modes. It is also concluded that the effect of a cutout becomes more pronounced as the thickness of the plate approaches the size of cutout.

Characteristics of Natural Frequencies of Steam Turbine Blades : 2nd Report, Influence of Disk on Vibration of Grouped Blades

Abstract: A method of calculating the natural frequencies of the axial vibrations of steam turbine blades and thick disks is presented, and the natural frequencies of blades are calculated and compared with the measured values. It is found that the difference between the calculated and measured values is within 10 per cent. The natural frequencies become higher at about 30 per cent depending on the defaults of the rotary inertia and the shear deformation. The effect of rotary inertia is small, while that of shear deformation is large. The relationship between the number of nodal diameters and natural frequencies is made clear by calculation.

Acceleration limit-value switch

Abstract: The acceleration limit-value switch is provided for motor vehicles and has an inertia body which is seated on a bed and is held in a quiescent position by magnetic forces. Said forces are exerted by a permanent magnet which is provided in the underneath of the inertia body and acts on an iron part. There is a defined air gap between the permanent magnet and the iron part. In consequence, the magnetic force can be set very precisely, so that the critical acceleration or deceleration value at which the inertia body is deflected can be set exactly. The defined air gap also prevents contamination influence.