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Showing papers on "Rotary inertia published in 2002"


Journal ArticleDOI
TL;DR: In this paper, a refined higher order shear deformation theory is used to investigate the dynamic instability associated with composite plates with delamination that are subject to dynamic compressive loads.

63 citations


Journal ArticleDOI
TL;DR: In this article, the parametric instability behavior of curved panels with cutouts subjected to in-plane static and periodic compressive edge loadings is studied using finite element analysis, considering the effects of transverse shear deformation and rotary inertia.

54 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of transverse shear and rotary inertia on large amplitude vibration for a laminated plate in a general state of nonuniform initial stress are derived.

46 citations


Journal ArticleDOI
TL;DR: In this article, a dynamic analysis of laminated cross-ply composite non-circular thick cylindrical shells subjected to thermal/mechanical load is carried out based on higher-order theory.

44 citations


Journal ArticleDOI
TL;DR: In this article, the governing differential equations for the out-of-plane, free vibration of circular curved beams resting on elastic foundations are derived and solved numerically, taking into account the effects of rotary inertia and transverse shear deformation.
Abstract: The governing differential equations for the out-of-plane, free vibration of circular curved beams resting on elastic foundations are derived and solved numerically. The formulation takes into consideration the effects of rotary inertia and transverse shear deformation. The lowest three natural frequencies are calculated for beams with hinged–hinged, hinged-clamped, and clamped–clamped end constraints. The effects of various system parameters as well as rotary inertia and shear deformation on the natural frequencies are investigated.

33 citations


Journal ArticleDOI
TL;DR: In this paper, a generalization of the two-dimensional shear deformable laminated shell theory is presented, which is able to account for the interlaminar continuity of both displacements and transverse shear stresses.

29 citations


Journal ArticleDOI
TL;DR: In this article, the free vibration analysis of non-cylindrical (conical, barrel and hyperboloidal types) helical springs with circular section is performed using the stiffness matrix method and the exact concentrated element inertia matrix.

29 citations


Journal ArticleDOI
TL;DR: In this article, the approach of a drop to its equilibrium position is studied and the rate of approach to the terminal state and the contact angle are slightly reduced by inertia, but, above a critical Reynolds number, the approach becomes oscillatory.
Abstract: Capillarity is an important feature in controlling the spreading of liquid drops and in the coating of substrates by liquid films. For thin films and small contact angles, lubrication theory enables the analysis of the motion to be reduced to single evolution equations for the heights of the drops or films, provided the inertia of the liquid can be neglected. In general, the presence of inertia destroys the major simplification provided by lubrication theory, but two special cases that can be treated are identified here. In the first example, the approach of a drop to its equilibrium position is studied. For sufficiently low Reynolds numbers, the rate of approach to the terminal state and the contact angle are slightly reduced by inertia, but, above a critical Reynolds number, the approach becomes oscillatory. In the latter case there is no simple relation connecting the dynamic contact angle and contact-line speed. In the second example, the spreading drop is supported by a plate that is forced to oscillate in its own plane. For the parameter range considered, the mean spreading is unaffected by inertia, but the oscillatory motion of the contact line is reduced in magnitude as inertia increases, and the drop lags behind the plate motion. The oscillatory contact angle increases with inertia, but is not in phase with the plate oscillation.

24 citations


Journal ArticleDOI
TL;DR: In this paper, an improved transfer matrix method was developed to analyze nonlinear rotor-bearing systems, where the rotating shaft is described by the Timoshenko beam theory which considers the effect of the rotary inertia and shear deformation.
Abstract: An improved transfer matrix method is developed to analyze nonlinear rotor-bearing systems. The rotating shaft is described by the Timoshenko beam theory which considers the effect of the rotary inertia and shear deformation. A typical roller bearing model is assumed which has cubic nonlinear spring and linear damping characteristics. Transfer matrices for the Timoshenko shaft element, disk element, and nonlinear bearing element are derived and the global transfer matrix is formed. The steady-state response of synchronous, subharmonic, and superharmonic whirls is determined using the harmonic balance method. Two numerical examples are presented to demonstrate the effectiveness of this approach.

23 citations


Journal ArticleDOI
TL;DR: In this article, a variationally consistent layer-wise trigonometric shear deformation theory (LTSDT) has been extended to deal with free vibration of two-layered laminated cross-ply beams.
Abstract: In this paper, variationally consistent layer-wise trigonometric shear deformation theory (LTSDT) has been extended to deal with free vibration of two-layered laminated cross-ply beams. In this displacement based theory, constitutive relations between shear-stresses and shear-strains are satisfied in both the layers, and, therefore, shear correction factor is not required. In-plane displacement is such that the resultant of normal stress acting over the cross section is zero. Compatibility at the layer interface in respect of in-plane displacement is also satisfied. Present theory contains even less number of unknown variables than those of the first order shear deformation theory (FSDT). In the present formulation, effects of rotary inertia and other inertias are also included. The efficacy of the present theory is demonstrated through the illustrative example.

22 citations


Journal ArticleDOI
TL;DR: In this paper, the dynamic stability of a spinning unconstrained beam subjected to a pulsating follower force P 0 + P 1 cos Ωt is analyzed, where a concentrated mass is located at an arbitrary location on the beam, and the stability of the beam is studied with the mass at various locations.

Journal ArticleDOI
TL;DR: In this paper, the stability of a column with rotary inertia was investigated using nonlinear modeling and perturbation analysis, and the amplitude of post-critical flutter oscillations was determined.
Abstract: This study examines how a tip mass with rotary inertia affects the stability of a follower-loaded cantilevered column. Using nonlinear modeling and perturbation analysis, expressions are set up for determining the stability of the straight column and the amplitude of post-critical flutter oscillations. Bifurcation diagrams are given, showing how the vibration amplitude changes with follower load and other parameters. These results agree closely with numerical simulation. It is found that sufficiently large values of tip mass rotary inertia can change the primary bifurcation from supercritical into subcritical. This can imply very large motions for follower loads just beyond critical, contrasting the finite amplitude motions accompanying supercritical bifurcations. Also, the straight column may be destabilized by a sufficiently strong disturbance at loads far below the value of critical load predicted by linear theory. A similar change in bifurcation is found to occur with increased external (as compared to internal) damping, and with a shortening in column length. These effects are not revealed by linear modeling and analysis, which may consequently fail to predict even qualitatively the real critical load for a column with tip mass.

Journal ArticleDOI
TL;DR: In this article, the effect of inviscid plug flow on the stability of several hydroelastic systems is investigated by determining the absolute or convective nature of the instability from the linear dispersion relation.

Patent
19 Jun 2002
TL;DR: In this paper, a method for recognizing moment of inertia of asynchronous motor is presented, where the electrical motor is controlled to run at constant acceleration from angular velocity omega 1 of no load operation to angular velocity Omega 2 and recording the running time delta t by using control method of torque vector.
Abstract: The invention relates to a method for recognizing moment of inertia of asynchronous motor. For the purpose, following steps are taken. The electrical motor is controlled to run at constant acceleration from angular velocity omega 1 of no load operation to angular velocity omega 2 and recording the running time delta t by using control method of torque vector. By using control method of speed vector. The motor is controlled to run at constant angular velocity omega 3 of no load operation. The value of electromagnet torque is calculated based on the torque current component It at this time, so as to get the friction torque To of the motor. then based on the running time delta t and the friction torque Io, the moment of inertia Jo of the omtor is calculated. The invented method provides highaccuracy for recognizing these parameters, thus improving the performance of the method of vector control.

Journal ArticleDOI
TL;DR: In this article, a high-precision thick plate element has been applied to free vibration analysis of plates to study its performance, which has not only helped to include the effect of shear deformation but also made the element free from locking in shear.

Journal ArticleDOI
TL;DR: In this paper, the attitude controller based on moment of inertia distribution for a bias momentum satellite is discussed, which is represented in the form of product of inertia terms in the system inertia matrix.
Abstract: Analysis on the attitude controller based upon moment of inertia distribution for a bias momentum satellite is discussed. Spacecraft moment of inertia distribution is represented in the form of product of inertia terms in the system inertia matrix. The product of inertia between orthogonal body axes of the satellite is used to build a controller which controls the nutational motion caused by the angular momentum of the wheel. The attitude controller in the pitch axis controlling the pitch motion as well as nutational dynamics in the roll/yaw planes is analyzed in detail. Analytic expressions using linearized equations are derived providing further insight into the dynamic coupling effect among orthogonal body axes.

Journal ArticleDOI
TL;DR: In this paper, the dynamic response characteristics of cross-ply laminated composite cylindrical shells are studied using a higher-order displacement model, which accounts for the nonlinear variation of the in-plane and transverse displacements through the thickness, and abrupt discontinuity in slope of inplane displacements at any interface.
Abstract: Here, the dynamic response characteristics of thick cross-ply laminated composite cylindrical shells are studied using a higher-order displacement model. The formulation accounts for the nonlinear variation of the in-plane and transverse displacements through the thickness, and abrupt discontinuity in slope of the in-plane displacements at any interface. The effect of inplane and rotary inertia terms is included. The analysis is carried out using finite element approach. The influences of various terms in the higher-order displacement field on the free vibrations, and transient dynamic response characteristics of cylindrical composite shells subjected to thermal and mechanical loads are analyzed.

Patent
11 Dec 2002
TL;DR: In this paper, a piezoelectric harmonic motor consisting of a flexible gear, a rigid gear and a picolectric wave generator is used to produce low speed rotary output without installing speed reducers.
Abstract: A piezoelectric harmonic motor comprises a flexible gear, a rigid gear and a piezoelectric wave generator The piezoelectric wave generator comprises a piezoelectric driver and three-stage amplifying displacement amplifiers connected with the piezoelectric driver in hinge connecting mode, wherein, a first stage is triangle amplification; a second stage is lever amplification; a third stage is buckling amplification The number of the displacement amplifiers is 2kn, wherein, n is a wave number; k is an integer more than or equal to 2; the displacement amplifiers are uniformly distributed along the circumferential direction The piezoelectric wave generator is in contact with the flexible gear, and the flexible gear meshes with the rigid gear The utility model has the advantages that: the utility model can get low speed rotary output directly without installing speed reducers, is simple in structure, small in volume, light in weight, large in output moment, small in rotary inertia, high in precision, high in efficiency, low in noise, easy to control and good in braking property as well as response, produces no magnetic field, and gets no influence of magnetic field

01 Jan 2002
TL;DR: This study presents a mathematical model for determining the exact critical flow velocity of a pipeline composed of uniform modules and a case study is applied to a simply supported pipeline consisting of two, three, and more modules.
Abstract: The problem of fluid flow through flexible pipes has received a good deal of attention in the research literature. Pa.idoussis & Issid (1974) introduced the basic governing differential equations, where it was shown that the system could be subjected to both divergence and flutter instabilities. Laura et al. (1987) investigated bending motion of a simply supported pipeline conveying fluid using a power series method to solve the associated governing equations. Mishra & Upadhyay (1987) used a cylindrical shell model to account for the rotary inertia and shear deformation effects. Concerning system optimization, Borglund (1998) formulated the minimal structural-mass design problem for a fixed critical flow speed. Analysis was performed using the finite element method to solve the associated equation of motion of a cantilevered configuration. Based on the fact that an exact solution for a uniform pipe is available and well established, this study presents a mathematical model for determining the exact critical flow velocity of a pipeline composed of uniform modules. Design parameters include the wall thickness and the length of each module. As a case study, the developed model is applied to a simply supported pipeline consisting of two, three, and more modules. Clear design charts are given showing the functional behavior of the critical flow velocity with the selected design parameters.

Proceedings ArticleDOI
01 Jan 2002
TL;DR: In this paper, the authors developed a systematic theoretical analysis of the dynamic characteristics of turbomachinery dual rotor-bearing systems and verified the analysis results including critical speed map and bearing stiffness.
Abstract: It is very common for aircraft engines to have dual rotor or even triple rotor designs. Due to the complexity of having multiple rotor design, the transfer matrix methods have used in the past to deal with multiple rotor-bearing systems. However, due to transfer matrix method’s assumptions, sometimes resulted in numerical stability problems or root-missing problems. The purpose of this paper is to develop a systematic theoretical analysis of the dynamic characteristics of turbomachinery dual rotor-bearing systems. This dual rotor-bearing system analysis will start with a finite element (FEM) rotor-bearing system dynamic model, then using different methods to verify the analysis results including critical speed map and bearing stiffness. In an inertia coordinate system, a general model of continuous dual rotor-bearing systems is established based on a lagrangian formulation. Gyroscopic moment, rotary inertia, bending and shear deformations have been included in the model. From a point of view of the systematic approach, a solution of the finite element method is used to calculate the critical speeds by several different methods, which in turn can help to verify this dual rotor-bearing system approach. The effects of the speed ratio of dual rotors on the critical speed will be studied, which in turn can be used as one of the dual rotor design parameters. Also, both critical speeds are in effect functions of dual rotor speeds. Finally, the bearing stiffness between high speed and low speed shafts not only affect the critical speeds of the dual rotor system, but also affect the mode shapes of the system. Therefore, the bearing stiffness in between is of even greater importance in turbomachinery dual rotor or multiple rotor design.Copyright © 2002 by ASME

Journal ArticleDOI
TL;DR: In this paper, a fiber-reinforced composite shaft design is optimized in two stages, first, the shaft natural frequency is maximized with the constraint imposed on the shaft buckling torque and torsional strength.
Abstract: In this study a fiber-reinforced composite shaft design is optimized. The optimization procedure is carried out in two stages. First, the shaft natural frequency is maximized with the constraint imposed on the shaft buckling torque and torsional strength. In the second stage of optimization, shaft weight is minimized with the constraint imposed on the natural frequency obtained from the first stage, shaft buckling torque and torsional strength. Shafts of uniform layup and uniform wall thickness (UU), uniform fiber layup and variable wall thickness (UV), variable fiber layup and uniform wall thickness (VU) and variable fiber layup and variable wall thickness (VV) have been considered. The shaft is modelled as a simply supported Timoshenko beam in which shear deformation, rotary inertia and gyroscopic effects are included. Rayleigh-Ritz displacement are used for deriving the solution equation. A Simulated Annealing (SA) global optimization routine is used. Although this routine requires large number of function evaluations to find the optimum solution, it finds the global optimum with high probability even for ill conditioning functions with numerous local minima.


Journal ArticleDOI
TL;DR: In this article, the buckling and vibration behavior of curved panels subjected to various in-plane tensile edge loadings using the finite element method was studied using the first order shear deformation theory.
Abstract: The buckling and vibration behaviour of curved panels subjected to various in-plane tensile edge loadings are studied using the finite element method. The first order shear deformation theory is used to model the doubly curved panels, considering the effects of transverse shear deformation and rotary inertia. The theory used is extended from the dynamic, shear deformable theory based on the Sander's first approximation for doubly curved shells, which can be reduced to Love's and Donnell's theories by means of tracers. The in-plane non-uniform internal stresses are obtained as the plane elasticity solution with reasonable accuracy, based on which the buckling and vibration results are obtained. The effects of different edge loadings, aspect ratio, thickness ratio, shallowness parameters are considered in the buckling and vibration analysis.

Journal ArticleDOI
TL;DR: In this paper, the mass parameters (measure of stability) are estimated for different support parameters and modified Reynolds numbers by adopting a non-linear time transient analysis, and the fluid inertia effect is taken in the analysis when modified Reynolds number is around one.
Abstract: In the analysis of hydrodynamic journal bearings the effect of fluid inertia is usually ignored in view of its negligible contribution compared to viscous force. However, the fluid inertia effect is to be taken in the analysis when modified Reynolds number is around one. Flexibly supported journal bearings are in general more stable when support design is proper. The aim of this paper is to see if there is any effect of fluid inertia on flexibly supported journal bearings. The mass parameters (measure of stability) are estimated for different support parameters and modified Reynolds numbers by adopting a non-linear time transient analysis.

Proceedings ArticleDOI
01 Jan 2002
TL;DR: In this article, a theoretical model based on the Bernoulli-Euler beam theory was developed for the transverse vibrations of a single bellows expansion joint restrained against rotation on either end.
Abstract: The paper presents the results of investigation of transverse vibrations of single bellows expansion joint restrained against rotation on either end. A theoretical model is developed based on the Bernoulli-Euler beam theory and includes added mass of the fluid flowing inside the pipe-bellow-pipe assembly. Neglecting effects of shear and rotary inertia an exact frequency equation is derived for the transverse vibrations of single bellows expansion joint including the effects of end elastic restraints against rotation. Numerical results are presented for an example bellow showing the effects of variation of elastic restraints and internal pressure on the first four modes of vibration.© 2002 ASME

Journal ArticleDOI
TL;DR: In this paper, the Schrodinger fluid was applied to the calculations of the moments of inertia of axially deformed nuclei to study the rotational motion of independent nucleon systems.
Abstract: The single particle Schrodinger fluid is applied to study the rotational motion of independent nucleon systems. Accordingly, we have applied the description of this Schrodinger fluid to the calculations of the moments of inertia of the axially deformed nuclei. As examples for the application of this concept to the calculations of the nuclear moments of inertia we have calculated the cranking-model, the rigid body-model and the equilibrium moments of inertia of the axially deformed nuclei 24Mg, 25Al, 27Al, 183W and 238Pu. The variations of the moments of inertia of these nuclei with the deformation parameter β have also been given.

Journal ArticleDOI
TL;DR: In this paper, a system-frequency mechanical filter was designed and installed in the generator-and-rectifier section of the turbine set, which normally operates in a non-resonant state with only a low inertia constant such that the system operation is not affected.

Proceedings Article
04 Sep 2002
Abstract: A semi-analytical method is developed in conjunction with shearable shell theory and modal expansion approach to predict the influence of geometrical non-linearities on free vibrations of anisotropic laminated cylindrical shells. The shear deformation and rotary inertia effects are taken into account in the equations of motion. The hybrid method developed in this theory is a combination of classical finite element approach, shearable shell theory and modal coefficient procedure. The displacement functions are obtained by the exact solution of the equilibrium equations of anisotropic cylindrical shells and thereafter, the mass and linear stiffness matrices are derived by exact analytical integration. Green's exact strain-displacement relations are used to obtain the modal coefficients for these displacement functions. The second- and third-order non-linear stiffness matrices are then calculated by precise analytical integration and superimposed on the linear part of equations to establish the non-linear modal equations. The linear and non-linear natural frequency variations are determined as a function of shell parameters for different cases. The comparison shows that the numerical analysis is of good reliability on the prediction of the experimental results.

Journal ArticleDOI
TL;DR: In this paper, the dynamical behavior of a simple rotating mechanical system that carries a charge on its surface and is accelerated by a falling mass is considered and it is shown that a fraction of the total kinetic energy is missing and that exactly this fraction of energy has been stored in the magnetic field distribution.
Abstract: The dynamical behavior of a simple rotating mechanical system that carries a charge on its surface and is accelerated by a falling mass is considered. It is shown that a fraction of the total kinetic energy is missing and that exactly this fraction of energy has been stored in the magnetic field distribution. The conservation of electromagnetic angular momentum is also discussed on the same basis. The concept of an electromagnetic moment of inertia is introduced to establish a close parallel with the concept of mechanical moment of inertia in classical dynamics. It is suggested that the present mechanical system can be used as a teaching tool at the early-to-intermediate level of an undergraduate physics program to ease the transition from the dynamics of rigid bodies to that of more abstract fields.

Journal ArticleDOI
TL;DR: In this paper, the effects of mass and rotary inertia variation on system response were investigated in detail, and the results showed that increasing rotary mass and inertia could reduce the random response of the beam structure and was quite sensitive to the tip mass variation.
Abstract: Nonlinear large amplitude random vibration of cantilever beam with lumped mass and rotary inertia under zero mean, stationary, Gaussian random base excitation is studied, using the inextensional beam theory. Single-mode approximation is employed to discretize the Lagrange's equation. The resulting nonlinear governing modal equation of motion is solved with application of the stochastic linearization method. Two examples, a cantilever beam with/without tip mass, are analyzed as application of the developed methodology. Effects of mass and rotary inertia variation on system response are investigated in detail. Results showed that increasing rotary inertia could reduce the random response of the beam structure and the random response of the structure is quite sensitive to the tip mass variation. The nonlinearities of the inextensional beam vibration result in a spring hardening system.