Showing papers on "Rotary inertia published in 2000"

On dispersion relations in piezoelectric coupled-plate structures

Abstract: This paper presents the dispersion relations for wave propagation in piezoelectric coupled plates based on Kirchhoff and Mindlin plate theories. Two layers of piezoelectric actuators are surface bonded on the plate and poled in the transverse direction to induce flexural action. A half-cosine distribution for the electric potential in the transverse direction is assumed and the Maxwell static electricity equation is imposed for the piezoelectric layers. This assumption is verified numerically by finite-element analysis using a simple beam example. Based on Kirchhoff plate theory, a virtually linear relationship between the non-dimensional phase velocity and the non-dimensional wave number is obtained similar to that for pure plate structure. Based on Mindlin first-order plate theory, which accounts for the effects of both shear and rotary inertia, the phase velocity-wave number relationship deviates from linearity when the wave number is not small relative to the thickness of the beam. The phase velocity approaches a finite value, corresponding to the velocity of the Love wave, for large wave number in contrast to that based on Kirchhoff plate theory. The cut-off frequency is found to be a function of the ratio of the shear and flexural rigidities. The presence of the piezoelectric materials has the effect of reducing the phase velocity which is evident from the results of both Kirchhoff and Mindlin theories. Comparisons of the dispersive characteristics based on the two-plate models for different piezoelectric layers are also conducted by using a PZT actuator and a piezo-film sensor in the numerical simulations.

A higher order plate theory for dynamic stability analysis of delaminated composite plates

Abstract: A higher order shear deformation theory is used to investigate the instability associated with delaminated composite plates subject to dynamic loads. Both transverse shear and rotary inertia effects are taken into account. The procedure is implemented using the finite element method. Delamination is modeled using the penalty parameter approach. The natural frequencies are computed and compared with NASTRAN 3D results and available experimental data. The effect of delamination on the critical buckling load and the first two instability regions is investigated for various loading conditions, plate thickness and boundary conditions. As expected the natural frequencies and the critical buckling load of the delaminated plate are lower than those of the nondelaminated plate. They decrease with increase in delamination length. Increase in delamination length causes instability regions to be shifted to lower parametric resonance frequencies and the normalized width of the instability regions to increase.

Dynamic instability of laminated composite rectangular plates subjected to non-uniform harmonic in-plane edge loading:

Abstract: The dynamic instability behaviour of isotropic, cross-ply and angle-ply laminated composite plates under combined uniaxial and harmonically varying in-plane point or patch loads is investigated using finite element analysis. The first-order shear deformation theory is used to model the composite laminates, considering the effects of transverse shear deformation and rotary inertia. The effects of various geometrical parameters, boundary conditions, lamination and load parameters on the principal dynamic instability regions of composite plates are studied in detail. The preferential orientations depending on the instability regions for simply supported patch and point loaded plates have been suggested for angle-ply plates. The dynamic instability region has been influenced by the restraint provided at the edges.

Non-linear dynamic stability characteristics of elastic plates subjected to periodic in-plane load

Abstract: Using a C1 QUAD-8 shear-flexible plate element, based on a new kind of kinematics which allows one to exactly ensure the continuity conditions for displacements and stresses at the interfaces between the layers in the laminates, the non-linear instability behaviour of plates subjected to periodic in-plane load has been studied. The formulation is general in the sense that it includes anisotropy, transverse shear deformation, in-plane and rotary inertia effects. Primarily, an attempt is made here to understand the geometrically non-linear parametric instability characteristics of isotropic and composite plates through a finite element formulation with dynamic response analysis. The non-linear governing equations obtained here are solved using the Newmark integration scheme coupled with a modified Newton–Raphson iteration procedure. The analysis brings out various characteristic features of the phenomenon, which are known from experiments, i.e. existence of beats, their dependency on the forcing frequency, the influence of initial conditions and load amplitudes, and the typical character of vibrations in the different regions.

Finite-Element Dynamic Analysis of a Rotating Shaft with or without Nonlinear Boundary Conditions Subject to a Moving Load

Abstract: A C0 continuity isoparametricfinite-element formulation is presented for the dynamic analysis of arotating or nonrotating beam with or without nonlinear boundaryconditions subject to a moving load. The nonlinear end conditions arisefrom nonlinear rolling bearings (both the nonlinear stiffness andclearance(s) are accounted for) supporting a rotating shaft. The shaftfinite-element model includes shear deformation, rotary inertia, elasticbending, and gyroscopic effect. Lagrange's equations are employed toderive system equations of motion which, in turn, are decoupled usingmodal analysis expressed in the normal coordinate representation. Theanalyses are implemented in the finite-element program ‘DAMRO 1’.Dynamic deflections under the moving load of rotating and nonrotatingsimply supported shafts are compared with those obtained using exactsolutions and other published methods and a typical coincidence isobtained. Samples of the results, in both the time and frequencydomains, of a rotating shaft incorporating ball bearings are presentedfor different values of the bearing clearance. And the results show thatsystems incorporating ball bearings with tight (zero) clearance have thesmallest amplitude-smoothest profile dynamic deflections. Moreover, fora system with bearing clearance, the vibration spectra of the shaftresponse under a moving load show modulation of the system naturalfrequencies by a combination of shaft rotational and bearing cagefrequencies. However, for a simply supported rotating shaft, the firstnatural frequency in bending dominates the response spectrum. The paperpresents the first finite-element formulation for the dynamic analysisof a rotating shaft with or without nonlinear boundary conditions underthe action of a moving load.

Moments of inertia for multiquasiparticle configurations

Abstract: Tilted-axis cranking calculations have been performed for multiquasiparticle states in well-deformed $A\ensuremath{\approx}180$ nuclei. In the limit of zero pairing, not only are the calculated moments of inertia substantially smaller than for rigid rotation, but also they are close to the experimental values. The moments of inertia are found to be insensitive to dynamic pair correlations.

Centrifugal flywheel with self adaptable rotary inertia

Abstract: The utility model relates to a centrifugal flywheel with self-adapting rotational inertia, which is characterized in that a heavy block and a tension spring are arranged in a hollow channel of a wheel spoke, wherein, the heavy block is connected to one end of the tension spring, wherein, the other end of the tension spring is connected to a wheel hub. The heavy block can be reciprocated in the hollow channel of the wheel spoke, wherein, two inner sides of which are provided with a plurality of positioning springs and steel balls. The utility model has the advantages of simple structural design and reliable operation. Energy storage and energy release can be dynamically changed. Corresponding variation can be done by the rotational inertia according to the variation of working condition of the utility model which has self-adapting characteristic and energy-saving effects.

Dynamic Stability of a Free-Free Cylindrical Shell Under a Follower Force

Abstract: The dynamic stability of a completely free isotropic circular cylindrical shell under a follower force is investigated. The first-order shear deformation and rotary inertia are included in the kinetic energy and the strain energy. A finite element model of the shell is formulated using the trigonometric ring element in the circumferential direction and the Lagrangian element in the longitudinal direction. Using the eigenvalue curves and the method of multiple scales, the dynamic stability is studied for the case of the follower force with a pulsating part as well as the constant follower force. The effect of the thickness ratio and the length ratio is presented in both cases. The numerical results for the shells are compared with those of a beam model having equivalent dimensions. The numerical results show that the shell under a constant follower force behaves like a beam in a certain range. The analysis of the shell under a pulsating follower force shows that the beamlike modes of the shell have larger unstable regions than the other modes. However, for the case of a pulsating load, the modes of higher circumferential wave number are of importance in that the combination resonance of difference type takes place frequently.

Out-of-plane bending and torsional resonance frequencies and mode shapes of symmetric cross-ply laminated beams including shear deformation and rotary inertia effects

Abstract: In this study, the stiffness method solution based on the first order shear deformation theory is used for the purely out-of-plane (out-of-plane bending and torsional) free vibration analysis of symmetric cross-ply laminated beams. A beam element has six degrees of freedom. The influence of the rotary inertia terms is included in the solution. Accounting for the shear deformation effects, the exact numerical element stiffness matrix is obtained based on the transfer matrix method. The element inertia matrix consists of the concentrated masses. The sub-space iteration and Jacobi's methods are employed in the solution of the large-scale general eigenvalue problem. The out-of-plane vibration mode shapes associated with the first eight natural frequencies of the vibration composite beam with several boundary conditions are illustrated. Copyright © 2000 John Wiley & Sons, Ltd.

Effect of Fluid Presence on the Nonaxisymmetric Dynamic Response of Buried Orthotropic Cylindrical Shells Under a Moving Load

Abstract: This paper deals with the nonaxisymmetric dynamic behavior of fluid-filled buried orthotropic cylindrical shells/pipes subjected to a load moving along the axis of the shell. A thick shell model including the effects of shear deformation and rotary inertia is considered. A perfect bond between the shell and sur rounding soil is assumed. The linear acoustic equation is used for the wave propagation in the fluid inside the pipe. Results are presented for the axisymmetric as well as the flexural mode for different orthotropy para meters of the shell and for different soil conditions around the pipe. Results of empty and fluid-filled shells are compared. The presence of fluid inside the shell has small effect on the shell response. However, the deformations in the fluid-filled shell are normally more than those in the empty shell. The difference in the displacements of empty and fluid-filled shells is very small in flexural mode as compared to axisymmetric mode. The effect of fluid presence on the shell respo...

Balancing device for a four-cycle engine

Abstract: There is provided a balancing device for a four-cycle V-type eight-cylinder engine having a bank gap angle of 90 degrees, characterized by provision on a common rotating shaft (balance shafts 8 1 , 8 2 as described in the mode for carrying out the invention) a part (an equivalent inertia mass P in the mode for carrying out the invention) for generating a first inertia force for offsetting a residual secondary inertia force from piston systems and a part (equivalent inertia masses VH, VV as described in the mode for carrying out the invention) for generating a second inertia force for offsetting a residual inertia force from valve systems. According to this construction, since balancing devices for piston and valve systems can be integrated into one unit, there is involved no complexity in construction.

Impact induced dynamic failure of laminated composite pretwisted rotating plates

Abstract: A transient dynamic finite element procedure is presented for failure analysis of centrally‐impacted laminated composite pretwisted rotating plates. A nine‐noded, three‐dimensional degenerated composite shell element is developed and used for the present finite element formulation. Effects of transverse shear deformation and rotary inertia are included. The strength‐of‐material type failure criteria are adopted and the “total ply discount” approach is used as the stiffness reduction model. The dynamic equilibrium equation is derived by applying Lagrange’s equation of motion and the investigation is carried out for moderate rotational speeds for which the Coriolis effect is negligible. The modified Hertzian contact law is utilized to compute the contact force between the impactor and the laminated plate. Impact failure analyses of pretwisted rotating plates are performed to investigate the effects of angle of twist, rotational speed and laminate configuration.

Stresses in Composite Shafts Subjected to Unbalance Excitation and Transmitted Torque

Abstract: In the present study, stress analysis of fiber reinforced thin composite shafts subjected to unbalance excitation and steady torque, is carried out. Shafts of uniform as well as variable wall thickness are considered. The shaft is modeled as a simply supported Timoshenko beam in which shear deformation, rotary inertia and gyroscopic effects have been included. Modified equivalent modulus beam theory has been adopted. Rayleigh-Ritz displacements are used for deriving the solution equations. Shafts with a uniform wall thickness, and with variable wall thickness in which the thickness is varied along the axial length of the shaft for three different cases of fiber angles have been studied. Axial variation of stresses is studied in detail. Results obtained indicate that the stresses in the variable wall thickness are smaller than the one with uniform wall thickness, even for the same weight of the shaft.

Interlude of operator pairs and a von Kármán plate-beam problem with rotational inertia

Abstract: In this paper we consider a non-dissipative Von Karman plate-beam which serves as a model for the undamped transversal vibrations of a two-dimensional plate which has a beam attached to its free cdgc.Rotational moments of inertia are included for both the plate and the beam and the problem is doubly non-linear in the sensc that large deflection occur in the form of an implicit evolution problem with cause and effect in different spaces. A subtle interplay of the operator pairs acting in the evolution problem cnables us to establish the existence of a unique global classical solutions for the platc-beam problem. This is achieved by using the theory of evolution operators in cmpathy to trcat the linear evolution problem and fixed point arguments in the study of the non-lincar problem.

A Study on the Method for Deducing the Inertia Moment of an Engine

Abstract: WT5”BZ] The inertia moment is an important parameter,for example,it is necessary for the on line rapid estimating power performance of engine that is based on the principle of inertia acceleration under no load.In this paper,some current method for determining the inertia moment of moving parts of engine are discussed and a new method——transient rotational speed method to deduce inertia moment is proposed,its principle is also presented.It deduces inertia moment by means of measured transient rotational speed and cylinder pressure under steady conditon and lower speed.This method is experimented at a model 185 diesel,the experimental results indicate that its accuracy is within 3%.Based on calculating and experimental results,the factors that influence measuring accuracy of the method are discussed and some improvements are proposed. [WT5”HZ]

Device and method for manufacturing formed vessel equipped with rotary inertia type stopper pin of base paper

Abstract: PROBLEM TO BE SOLVED: To provide a device and a method for manufacturing a formed vessel equipped with an improved type base paper stopping system. SOLUTION: A plurality of inertia type stopper pins of base paper are arranged so as to position a vessel base paper 60 before pressing formation. When the vessel base paper 60 is supplied to the device, the freely rotary stopper pins 40, 42, 44, 46 absorb its kinetic energy and therefore are rotated and solve the impetus of base paper. Furthermore, a plate 34 is formed by utilizing an improved device incorporating the inertia type stopper pin of base paper. COPYRIGHT: (C)2001,JPO