bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling of an Elastic Disk With Finite Hub Motions and Small Elastic Vibrations With Application to Rotordynamics
Authors: Flowers George T. 
Published: April 2021

Abstract
In the modelling of flexible structures undergoing large overall motion and small elastic vibrations, it is necessary to include elastic displacement effects up to second order if the resulting equations are to be consistent. Elastic displacements are typically modelled using mode shapes and generalized coordinates, an approach that neglects displacement effects that are higher than second order in the generalized coordinates. This study examines the implications of such effects in the modelling of an elastic disk with arbitrary base motions and small elastic vibrations. A general modelling procedure is described that is appropriate for the development of simulation models for such structures. An approximate technique is used to account for the second order elastic displacements. The model is specialized to the case of an elastic disk undergoing a constant axial spin and infinitesimal displacements for all other degrees of freedom. Comparisons are made between the natural frequencies of this model with and without foreshortening effects and some conclusions are drawn as to the relative importance of such terms in rotor disk modelling.
On the Dynamics of a Beam Rotating at Nonconstant Speed
Authors: Huang Yii-Mei , Lin Ming-Shang 
Published: April 2021

Abstract
The response and its stability of a beam rotating at nonconstant angular speed are studied. The rotating speed is assumed to be the combination of a constant angular speed and a small periodic perturbation. The axial and flexural deformations due to rotation are considered simultaneously. Thus, the rotating team at nonconstant speed yields a set of parametric excited partial differential equations of motion. Extended Galerkin’s method is employed for obtaining the discrete equations of motion. Then, the solution and the its stability are found by using the method of multiple scale.
The Influence of Mounting Compliance and Operating Conditions on the Radial Stiffness of Ball Bearings: Analytic and Test Results
Authors: Butner M. F. , Murphy B. T. , Akian R. A. 
Published: April 2021

Abstract
Ball bearing stiffness is significantly affected by internal clearance as well as the nature of applied loads and bearing ring mounting compliance. Since their stiffnesses are key to rotor critical speeds, it is important to obtain the most accurate possible radial stiffness prediction for shaft bearings during the machine design analysis process. Quasi-static analysis of spring-preloaded ball bearings predicted reduced radial stiffness when the outer ring is permitted to tilt rather than being assumed restrained from angular deflection. This effect was confirmed experimentally by observing resonant frequencies of a rotor supported on ball bearings of varied internal clearance, mounted with and without spring preloading. Analytic predictions of bearing stiffness are given, and test results presented for comparison.
Influence of Thermal Conductivity of Lubricant on the THD Characteristics of a Plain Journal Bearing
Authors: Rajalingham C. , Prabhu B. S. , Bhat R. B. , Xistris G. D. 
Published: April 2021

Abstract
The viscous heat generation in the lubricant film of a hydrodynamic journal bearing causes a rise in temperature of the fluid film. Considering the influence of the temperature variation along and across the film, the performance of a journal bearing is investigated under adiabatic conditions for different values of thermal conductivity of the lubricant. In this analysis, the temperature of the journal surface has been chosen to ensure that there is no net heat transfer from the lubricant The results show that the variation of temperature across the film affects bearing performance significantly and that an increase in lubricant thermal conductivity enhances bearing performance.
Jumping Phenomenon in Journal Bearing
Authors: Kryniski Krystof 
Published: April 2021

Abstract
Due to their reliability and low maintenance costs over an extended service time, the journal bearings, also known as fluid-film bearings, are commonly incorporated in the super-critical rotor systems. Together with proven balancing methods, they allow rotating machine to pass smoothly through the various of critical speeds, both during start-ups and shut-downs. However, journal bearings need to be designed very carefully, as at some operating conditions (speed and load), they may introduce the undesired effects, such as unstable operations or sub-harmonic resonances. The standard procedure leading to the optimum fluid-film bearing design is based on the bearing capacity, defined by the Sommerfield number [1][2]. When Sommerfield number is determined, all design parameters, such as viscosity, radial clearance, diameter and rotation speed, etc. are matched to satisfy the engineering requirements specified. The procedure is considered to be completely reliable and is commonly used in turbo-machinery and high-speed compressor design. However, the significant divergences between theory and practice were observed with the increase of a bearing radial clearance [3].
The Effect of Bistable Jump on the Reliability of Squeeze Film Damper
Authors: Changsheng Zhu 
Published: April 2021

Abstract
Based on lots of data from an experiment of a high-speed rotor supported on squeeze film dampers, this paper analyses that how the bistable jump affects the reliability of squeeze film dampers, if the rotor system has to frequently pass through the bistable oparation speed range. It is shown that the change of the rotor vibration amplitudes caused by times of passed through bistable operation speed range is more significant than that caused by steady operating time. The users must pay much attention to the bistable jump phenomenon in the successful application of squeeze film dampers.
Investigation on the Bistable Jump in Subcritical Speed Range of Rotor Supported on Uncentralized Squeeze Film Dampers
Authors: Changsheng Zhu , Xixuan Wang , Caigao Fu 
Published: April 2021

Abstract
This paper presents one of bistable jump phenomena observed in rotor system supported on uncentralized squeeze film dampers which occurs in the subcritical speed range of rotor. The jumping tendency of this bistable jump is jumping up in acceleration and jumping down in deceleration and is without the transposition of disk mass centre. The behaviors, especially the latter, are different from the bistable jump behaviors reported to date. The reason for occurrence of the subcritical speed bistable jump is explained by a Duffing equation with the varied stiffness and the exciting force which amplitude is proportional to the square of rotating speed of rotor.
Dynamic Torque Response of an Electro-Rheological Clutch
Authors: Firoozian R. , Bullough W. A. , Xiao S. , Hosseini-Sianaki A. , Johnson A. R. , Makin J. 
Published: April 2021

Abstract
The main potential advantage of electro-rheological fluid when used as the interface medium between electronics and actuators in high speed machines is its ability to respond quickly to a change in the control signal. The analysis reported in this paper shows that over the operating speed range the system has a time constant of less than one millisecond and for most practical applications it can be assumed that when a suitable control strategy is employed the output torque would be proportional to the control signal.
Most electro-mechanical torque transducers have time constant of over 10 milliseconds and therefore direct measurement of the torque produced by the electro-rheological clutch would be very expensive if not impractical. This paper reports a numerical method of identifying the torque response from the output of a conventional torque transducer which has a natural frequency of 110 Hz. The transfer function is first identified from a standard step input test, and the torque response of the clutch then is estimated from the measured signal. Although the noise on the signal will be always amplified with this method the use of a digital filter makes it possible to obtain an accurate estimate of the torque response.
Progressive Torsional-Axial Continued Vibrations in Crankshaft Systems: A Phenomenon of Coupled Vibration
Authors: Song X. G. , Song T. X. , Xue D. X. , Li B. Z. 
Published: April 2021

Abstract
It has been recognized that the effects of coupled vibrations are the most important when the natrural frequencies of torsional and axial vibrations are equal to each other or that axial natrural frequency is double of that of torsional. Especially the response of axial vibration, which frequency is double of that of torsional resonance, may become very serious.
Two types of coupled vibration between torsional & axial vibration in crankshafting are introduced. And the method to calculate the coupled vibrations at the same frequency and at the double frequency of axial to torsional is presented.
Dynamic model tests & torsional and axial vibration tests of practical crankshaftings on board have been performed. From the tests and calculations, a phenomenon of torsional-axial continued vibration, progressive in nature, as a result of coupled vibration are revealed.
A Review of the Dynamics of Independently Rotating Wheel Systems for Railway Vehicles
Authors: Swamy S. Narayana , Dukkipati R. V. , Osman M. O. M. 
Published: April 2021

Abstract
Major analytical and experimental efforts in the field of Independently Rotating Wheel systems (IRW) for railway vehicles have been reviewed. Various methods adopted by researchers to incorporate guidance capability to the system are discussed. Attention is focussed on the lateral stability and response characteristics of IRW systems and mathematical models developed to predict them. Some critical research needs are identified.
A Study of Control Strategy for Vehicle Semi-Active Suspension System
Authors: Zhang Yiming , Lin Ye 
Published: April 2021

Abstract
This paper investigates a reference control strategy for Vehicle semi-active suspension. The control is conducted by following the idea optimal active controller. The passive actuator is set to optimal whenever the active and passive actuators have the same signs; and set to zero output whenever the two signs are opposite. The simulation results of a 2DoF vehicle show that the semi -active suspension system can follow the ideal active system very well, both are superior to conventional passive systems. In this paper, a 2DoF vehicle model was also used to study a statistical optimal control strategy of the semi-active suspension system. The statistical optimal concept is the result of the combination of the nonlinear programming and controllable damper. A way of estimating statistical characteristics of road irregularities was also proposed.
Vehicle active, suspension, due to its perfect v i bra t i on isolation performance, gets moreand more attention. Active suspension can be generally divided into two categories, totally active suspension system and semi-active suspension system. From the published results it is known that active suspension can surpass the performance limit of conventional passive suspension and greatly improve the vehicle riding comfort and steering ability. But active suspension has a critical disadvantage of less applicability, due to its high cost and low reliability. Also it consumes large amount of energy as it works. The idea of semi-active suspension was put forward to overcome the shortcoming of active suspension. It is a compromise between active suspension and passive suspension. Semi-active suspension has approximately the same behavior as active suspension, and almost consumes no energy as it works. So semi-active suspension possesses a great potential in application. At. present, in the field of suspension research over the world, a great deal of attention is paied to semi-active suspension. At present, for the cotrol of semi-active suspension the widely studied strategy is “on off” control [1] [2], which is first put forward by Karnopp. “On-off” control can eliminate the phenomenon of vibration amplification for passive suspension, thus it can improve the suspension performance to certain extent. At present, no substantive result has been obtained yet in the field of optimal control of semi-active suspension. This paper will investigate a reference control strategy on the basis of linear optimal control. The control is conducted by following the optimal ctive controller. The referrence control result is optimal when the outputs of the active and semi-active force generators have the same signs.
A Transfer Matrix Technique for Evaluating the Natural Frequencies and Critical Speeds of a Rotor With Multiple Flexible Disks
Authors: Wu Fangsheng , Flowers George T. 
Published: April 2021

Abstract
Modern turbomachinery is used to provide power for a wide range of applications, from steam turbines for electrical power plants to the turbopumps used in the Space Shuttle Main Engine. Such devices are subject to a variety of dynamical problems, including vibration, rotordynamical instability, and shaft whirl. In order to properly design and evaluate the performance and stability of turbomachinery, It is important that appropriate analytical tools be available that allow for the study of potentially important dynamical effects. This research effort is concerned with developing a procedure to account for disk flexibility which can readily be used for investigating how such effects might influence the natural frequencies and critical speeds of practical rotor systems.
In the present work, a transfer matrix procedure is developed in which the disk flexibility effects are accounted for by means of additional terms included in the transfer matrix formulation. In this development, the shaft is treated as a discrete system while the disk is modelled as a continuous system using the governing partial differential equation. Based on this governing equation, an equivalent inertial moment Mk*, which is the generalized dynamic force coupling between shaft and disk, is then derived. Analysis shows that only the disk modes of one nodal diameter contribute to the inertial moment, Mk*, and thus influence the natural frequencies of the rotor system.
To determine the Mk*, the modal expansion method is employed and the governing partial differential equation of the disk is transformed to a set of decoupled forced vibration equations in the generalized coordinates. The Mk* are then calculated in terms of modal shapes, natural frequencies, and material and geometric parameters which can be found in the literature or can be obtained from experiments. Finally the Mk* are incorporated into the point transfer matrix. By so doing, the properties of quick computational speed and ease of use are retained and the complexity of solving partial differential equations is avoided. This allows the present procedure to be easily applied to practical engineering problems. This is especially true for multiple flexible disk rotor systems.
As an example, three different cases for a simplified model of the Space Shuttle Main Engine (SSME) High Pressure Oxygen Turbo-Pump (HPOTP) rotor have been studied using this procedure. Some of the more interesting results obtained in this example study are enumerated below.
1.) Disk flexibility can introduce additional natural frequency(s) to a rotor system.
2.) Disk flexibility can cause shifting of some of the natural frequencies.
3.) As disk flexibility is increased, lower natural frequencies of the rotor system will be influenced.
4.) At certain rotor speeds, disk flexibility may cause the disappearance of a natural frequency.
5.) The axial position of the disk on the rotor shaft has a significant effect on the degree of this influence.
Suppression of Subsynchronous Vibration in the SSME HPFTP
Authors: Becht David G. , Hawkins Larry A. , Scharrer Joseph K. , Murphy Brian T. 
Published: April 2021

Abstract
SSME HPFTP hot-fire dynamic data evaluation and rotordynamic analysis both confirm that two of the most significant turbopump attributes in determining susceptibility to subsynchronous vibration are impeller interstage seal configuration and rotor sideload resulting from turbine turnaround duct configuration and hot gas manifold. Recent hot-fire testing has provided promising indications that the incorporation of roughened “damping” seals at the impeller interstages may further increase the stability margin of this machine. A summary of the analysis which led to the conclusion that roughened seals would enhance the stability margin is presented herein, along with a correlation of the analysis with recent test data.
Effect of Axial Vibrations on the Dynamics of a Helical Gear Pair
Authors: Kahraman Ahmet 
Published: April 2021

Abstract
In this paper, a linear dynamic model of a helical gear pair has. been developed. The model accounts for the shaft and bearing flexibilities, and the dynamic coupling among the transverse, torsional, axial and rotational motions because of the gear mesh. The natural frequencies and the mode shapes have been predicted, and the modes which are excited by the static transmission error have been identified. The forced response due to the static transmission error has also been predicted, including the dynamic mesh and bearing forces. A parametric study has been performed to investigate the effect of the helix angle on the free and forced vibrational characteristics of the gear pair. It has been shown that the helix angle can be neglected in predicting the natural frequencies and the dynamic mesh forces. An accurate prediction of dynamic bearing forces and moments requires inclusion of helix angle in the analysis.
Asymmetric Response of a Pneumatic Spring
Authors: Jettappa Richard Rodrigues 
Published: April 2021

Abstract
The exact equations of motion of a pneumatic spring are derived. Both single sided and double sided springs are considered. The enclosing walls are assumed to be perfectly rigid. It is shown that the single sided spring exhibits marked asymmetric response when set into motion by a non-zero initial displacement. The peaks are sharp and the troughs are flattened. The amplitude of motion is different in positive and negative directions. The two sided spring gives a symmetric response but the peaks and troughs show sharp corners indicating non-linear response. It is shown that the mounted frequency depends upon only two system parameters, namely, the initial volume and the spring area in contrast to the existing linear theory in which it depends upon two additional parameters, namely, the initial pressure and the mounted mass. The dependance of period of oscillation on the amplitude of initial displacement is demonstrated.
FE Meshing Tool for the Dynamic Analysis of Beam-Like Structures
Authors: De Smet M. , Van Brussel H. , Sas P. 
Published: April 2021

Abstract
This paper outlines a methodology for the automatic creation of finite element meshes used for calculating structural dynamic behaviour. Starting from the idealized geometry of the structure, the proposed Intelligent Meshing Tool determines a mesh density that a priori guarantees the resonant frequencies to be calculated within predetermined accuracy limits. Unlike most existing techniques for automatic meshing, this technique is not inherently adaptive, but does not exclude an extra adaptive mesh refinement step, either. Implementation of this methodology is discussed for structures composed of straight uniform, curved and tapered beam-like components. The feasibility of the meshing strategy is illustrated by means of an example.
Force Identification From Dynamic Response of Bi-Material Beams
Authors: Doyle James F. 
Published: April 2021

Abstract
The dynamic response due to impact of a 2-D bi-material system is described in terms of a waveguide model involving two displacements and a rotation. Coupled with spectral analysis, this allows measured signals to characterize the waves propagating in the system; this in turn, is used to predict responses at any locations. In particular, the impacting force can be reconstructed. The results are demonstrated on an aluminum/epoxy system.
Natural Frequencies and Mode Shapes of Elliptic Plates With Boundary Characteristic Orthogonal Polynomials As Assumed Shape Functions
Authors: Rajalingham C. , Bhat R. B. , Xistris G. D. 
Published: April 2021

Abstract
The natural frequencies and natural modes of vibration of uniform elliptic plates with clamped, simply supported and free boundaries are investigated using Rayleigh-Ritz method. A modified polar coordinate system is used to investigate the problem. Energy expressions in Cartesian coordinate system are transformed into the modified polar coordinate system. Boundary characteristic orthogonal polynomials in the radial direction, and trigonometric functions in the angular direction are used to express the deflection of the plate. These deflection shapes are classified into four basic categories, depending on its symmetrical or antisymmetrical property about the major and minor axes of the ellipse. The first six natural modes in each of the above categories are presented in the form of contour plots.
Circumferential Vibrations of Three Layered Sandwich Cylinders
Authors: Hamidzadeh H. R. , Chandler D. E. 
Published: April 2021

Abstract
The problem of forced lobar vibrations of three layered cylinders of infinite extent subjected to boundary stresses which do not vary along the axis is considered. Linear viscoelastic theory is employed and the lobar vibrations of a thick single cylinder is accurately formulated. The solution to the three constrained layer cylinders is developed by utilizing the stresses and displacement at all interfaces, and by complying with the compatibility requirements at each interface. Computed results are compared with an available approximate solution and satisfactory agreement is established. The reported solution is exact and it is not limited to thin cylinders.
Dynamic and Static Design of Engine Test Benches
Authors: Pol P. Santamarina 
Published: April 2021

Abstract
The elastic mechanical strength of the large and medium reciprocating engine test benches, is calculated for vertical and horizontal bendings and for torsion. The dynamic loads - horizontal vibrating forces and vertical vibrating couples (bending and torsion) and horizontal vibrating couple,- and the static loads, - distributed weight of the bench itself and the machinery and the motor torque (torsion), - are analyzed. It is pointed out that the bench body of reinforced concrete is submitted to bending moments and shearing forces and to torsion couples. This paper is the continuation of the paper “Dynamic Loads in Engine Test Benches” in 12th Biennial ASME Conference on Mechanical Vibration and Noise.
An Experimental Study of Cutting Noise Dynamics
Authors: Ya Wu , Shiqiu Ke , Shuzi Yang , Qilin Zhang , Shanxiang Xu , Yaozu Wen 
Published: April 2021

Abstract
Up to now little has been reported on the cutting noise in metal-cutting machine tools at home and abroad. Based on the research results available, tests on the cutting noise have been performed on three power lathes and a type Mx-4 crankshaft connecting rod neck lathe. The cutter material is hard alloy YT6x, workpiece material is nodular cast iron QT60-2, the cutting mode is broadedge plunge type turning. The influences of the cutter form, cutter angle, cutting speed, and feed on the cutting noise have been investigated using the test results. It is pointed out that the machine tool dynamic characteristics are one of the primary factors that influence the cutting noise, that there is a correlation between the cutting noise and cutting force and that the main spectral peak frequency of the cutting noise is close to the first-order modal frequency of the workpiece system. The importance of the two new discoveries lies in that a breach has been found for investigations on cutting noise dynamics.