Showing papers on "Rotary inertia published in 1982"

Effects of Fluid Inertia and Viscoelasticity on Squeeze-Film Bearing Forces

Abstract: The Reynolds equation of hydrodynamic lubrication is normally used to determine the damping coefficients in the analysis of rotor-dynamic system with squeeze-film dampers. Lubrication theory assumes that the fluid motion is precisely in phase with the bearing surface motion, but at high speeds both inertia and viscoelasticity introduce phase-shifting effects into the fluid motion. As a result, predictions derived from Reynolds' equation can be significantly in error. An earlier series of papers developed a theory to account for the influences of viscoelasticity and inertia in arbitrary oscillatory squeezing flows of small amplitude. The theory is applied here to develop improved expressions for the linear damping coefficients, in terms of the Reynolds and Deborah number. Evaluation of the corrected formulae show that fluid inertia and viscoelasticity have large effects on the coefficients.

Thermal Buckling of Initially Stressed Thick Plates

Abstract: Equations of motion for a transversely isotropic thick plate with thermal effects in a general state of nonuniform initial stress where the effects of transverse shear and rotary inertia are included are derived. The method is to perturb the nonlinear equations of elasticity by an incremental deformation. The resulting equations are linearized and integrated through the thickness of the plate to obtain the thermal elastic plate equations. A reduced set of equations for a thick plate with thermal effects is also given. Finally, the thermal buckling problems are solved for a simply supported rectangular plate in a state of uniform compressive (or tensile) initial stress plus initial bending stress combined with uniform thermal compressive stress plus thermal bending stress. The effects of various parameters on thermal buckling loads are studied.

Beams Under Lateral Projectile Impact

Abstract: The influence of transverse shear effects, rotary inertia and the boundary conditions on the dynamic behavior of rigid perfectly plastic beams subjected to projectile impact at midspan is studied. Theoretical solutions for a perfectly clamped and a simply supported beam are presented. Numerical results are given for a rectangular and three wide-flanged I-beams of varying spans. For the particular range of parameters examined it is found that rotary inertia does not affect the response in a significant way. However, shear effects are very important for the particular beams considered, being more pronounced in wide-flanged short I-beams. In particular the maximum lateral displacement can increase substantially due to shear effects, showing that a bending only solution neglecting shear can lead to erroneous results. It is also found that shear effects are slightly more important for short simply supported beams than short clamped beams, but for large spans they are essentially independent of the support conditions.

An Influence of Inertia Forces on Stability of Turbulent Journal Bearings

Abstract: It is a purpose of this paper to discuss both turbulence and inertia effects on the static and dynamic characteristics of high speed journal bearings. Because of the difficulty of analysis, infinitely long and short width bearings are dealt with analytically instead of finite width bearings. It is found that the static characteristics such as the Sommerfeld number and the locus of shaft center are affected mainly by turbulence but the dynamic ones such as the spring, damping and acceleration coefficients of lubricant film and the stability of rotors are affected by inertia.

Collective rotations of asymmetrically deformed many-body systems

Abstract: The angular momentum projection technique is worked out for systems with an intrinsic asymmetric deformation. These include asymmetric top molecules and triaxial nuclei. A parameterisation of the rotation group is introduced which allows an approximate but analytical evaluation of angular momentum projected matrix elements. Via symmetric orthonormalisation a quantal definition of the moments of inertia is obtained.

Method and device for storing kinetic energy in a rotary mass.

Abstract: The flywheel has four upper (1) and four lower (1a) moving mass elements which set themselves between a minimum and maximum distance from the centre of rotation (3), under the influence of centrifugal force. In this way, the moment of inertia of the flywheel masses also varies between a minimum and a maximum value. In known flywheel masses, the moment of inertia is constant and determines the magnitude of the drive torque required. On the other hand, the proposed flywheel has to overcome only a reduced moment of inertia - on starting or accelerating from a reduced speed - so that now a reduced drive torque is adequate. On the other hand, in the case of the said drive torque, a greater storage capacity can be achieved in the end effect. The method and the flywheel can be used primarily in electrical drives, especially with a battery or accumulator.

An Analysis of Dynamic Characteristics of Turbulent Journal Bearings Considering Inertia Forces

Abstract: It is a purpose of this paper to present a means of handling both turbulent and inertia effects on the dynamic characteristics of finite width journal bearings. In the analysis turbulence is treated by means of turbulent coefficients and inertia forces are approximated by mean velocities averaged across the fluid film. Assuming a small displacement of journal center, the dynamic coefficients such as spring, damping and acceleration coefficients and the onset whirl frequencies of rotors are computed The results obtained show that the dynamic characteristics as mentioned above are affected by inertia forces.

Torque optimizing neutral inertia device

Abstract: A control system for rolling airframes utilizing variable pitch control surfaces includes a variable inertia device within the control system connected to the servo control motors that control the control surfaces, with the variable inertia device selectively controllable to optimize the inertia of the control system for optimizing the power requirements of the control system. The variable inertia means includes a rotatable mass with means for moving the effective position of the mass radially inwardly and outwardly from the rotary shaft of the control system for selectively varying the inertia of the control system.

Design charts for self-excited whirling critical speeds

Abstract: Using a generalised tailshaft model of the propulsion system, design charts are constructed for rapidly estimating the self-excited whirling critical speeds of the shafting system over a wide range of design parameters. These design-chart estimates may be refined to any desired accuracy by a program developed for a programmable hand calculator. The analysis includes propeller mass and rotary inertia, propeller gyroscopic effects, shaft mass and flexural rigidity, and partial fixity of the line shafting at the forward bearing. Entrained water may be included as a proportion of the propeller mass and inertia. The non-dimensional form of the design charts offers several advantages, for example, the option of employing any consistent system of units, or a quick assessment of the sensitivity of the critical whirling speeds to design parameters of the system. Comparison of the results from the charts with other methods of whirling estimation shows the advantages of the Author's approach.

Centrifugal timing control device

Abstract: PURPOSE:To prevent abnormal advance in a centrifugal timing control device of an internal combustion engine, by applying inertia action of a stable ring, movably fitted to an advance sleeve, to a weight and cancelling inertia actions of the advance sleeve and the weight CONSTITUTION:A stable ring 99, having a long hole 99a, is movably fitted to an advance sleeve 7, and an advance pin 55 is implanted to a weight 4, extended through a long hole 6a of an advance plate 6 and engaged to the long hole 99a Now a driving shaft 1 receives negative angular acceleration, if decelerated, the plate 6 and the sleeve 7 generate rotary torque to an advance side in accordance with a level of their rotary inertia, also the weight 4 jumps to open about a pin 3 as the axis, and rotary torque to an advance direction is generated also in the stable ring 99 To cancel the rotary torque of said stable ring 99 with the rotary torque of the plate 6, sleeve 7 and the weight 4, the pin 55 is engaged to the long hole 99a to stop the weight 4 jumping to open with force applied to the pull back direction In this way, abnormal advance can be prevented to obtain a stable prescribed advance characteristic

Static and Dynamic Analysis of Space Frameworks with Curved Members

Abstract: A nonconventional finite-element method is presented for the analysis of space frameworks composed of straight and curved members. In the analysis both static and dynamic loads, elastic-plastic deformations, strain hardening and hysteresis effects are taken into consideration. The elements of the stiffness and consistent mass matrices of the circularly curved beam-element in space are derived in closed-form, based on the exact solutions of previously developed Euler differential equations in terms of six deformations governing the in-plane and out-of-plane behavior of the curved element and accounting for the effects of extensional and shearing deformations. The effect of rotary inertia is also considered in the derivation of the consistent mass matrix. As a result of the formulation used in the present study, the distribution functions of stress resultants and deformations are exact within the element. Furthermore, the explicit forms of the stiffness and mass matrices reduce considerably the number of finite-elements needed to model a given structure and thus eliminate the need for extensive matrix operations in the computational algorithm. The applicability of the analytical method presented herein is demonstrated by the solution of some typical structures subjected to static and dynamic loads.