Coriolis Effect on the Vibration of a Cantilever Plate With Time-Varying Rotating Speed

1992 ◽  
Vol 114 (2) ◽  
pp. 232-241 ◽  
Author(s):  
T. H. Young ◽  
G. T. Liou
Keyword(s):  
Differential Equations ◽  
Multiple Scales ◽  
Parametric Instability ◽  
System Response ◽  
Coriolis Effect ◽  
Time Varying ◽  
Cantilever Plate ◽  
Rotating Speed ◽  
First Order ◽  
System Equation

A method for investigating the Corilois effect on the vibration of a cantilever plate rotating at a time-varying speed is presented in this paper. Due to this time-dependent speed, parametric instability occurs in the system. Furthermore, owing to the existence of the Coriolis force, the system equation is transformed, by a special modal analysis procedure, into independent sets of first-order simultaneous differential equations. This set of simultaneous differential equations is solved by the method of multiple scales, yielding the system response and the expressions for the boundaries of the unstable regions. Finally, the Coriolis effect on the changes in the boundaries of the unstable regions is investigated numerically.

Dynamic Response of Spinning Blades Subjected to Gyroscopic Motion

1994 ◽  
Vol 116 (1) ◽  
pp. 6-15 ◽  
Author(s):  
T. H. Young ◽  
G. T. Liou
Keyword(s):  
Differential Equations ◽  
Multiple Scales ◽  
Equations Of Motion ◽  
Parametric Instability ◽  
Spin Axis ◽  
System Response ◽  
First Order ◽  
System Equations ◽  
Element Technique ◽  
Gyroscopic Motion

This paper presents an investigation into the vibration and stability of a blade spinning with respect to a nonfixed axis. Due to the motion of the spin axis, parametric instability of the blade may occur in certain situations. In this work, the discretized equations of motion are first formulated by the finite element technique. Then the system equations are transformed, by a special modal analysis procedure, into independent sets of first-order simultaneous differential equations. Each set of differential equations is solved analytically by the method of multiple scales if the precessional speed of the spin axis is assumed to be small compared to the spin rate of the blade, yielding the system response and the expressions for the boundaries of the unstable regions. Finally, the effects of system parameters on the changes in these boundaries are studied numerically.

Model Based Temperature Control in RTP Yielding ±0.1 °C accuracy on A 1000 °C, 2 second, 100 °C/s Spike Anneal

1998 ◽  
Vol 525 ◽  
Author(s):  
Peter Vandenabeele ◽  
Wayne Renken
Keyword(s):  
Differential Equations ◽  
Temperature Control ◽  
Control Method ◽  
Nonlinear Differential Equations ◽  
System Response ◽  
Model Based Control ◽  
First Order ◽  
Model Based ◽  
Measured System ◽  
Spike Anneal

ABSTRACTA Model Based Control method is presented for accurate control of RTP systems. The model uses 4 states: lamp filament temperature, wafer temperature, quartz temperature and TC temperature. A set of 4 first order, nonlinear differential equations describes the model. Feedback is achieved by updating the model, based on a comparison between actual (measured) system response and modeled system response.

scholarly journals Nonlinear Response of Cantilever Beams to Combination and Subcombination Resonances

1998 ◽  
Vol 5 (5-6) ◽  
pp. 277-288 ◽  
Author(s):  
Ali H. Nayfeh ◽  
Haider N. Arafat
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
Multiple Scales ◽  
Method Of Multiple Scales ◽  
Virtual Work ◽  
Equations Of Motion ◽  
Nonlinear Ordinary Differential Equations ◽  
Response Curves ◽  
First Order ◽  
Aspect Ratios

The nonlinear planar response of cantilever metallic beams to combination parametric and external subcombination resonances is investigated, taking into account the effects of cubic geometric and inertia nonlinearities. The beams considered here are assumed to have large length-to-width aspect ratios and thin rectangular cross sections. Hence, the effects of shear deformations and rotatory inertia are neglected. For the case of combination parametric resonance, a two-mode Galerkin discretization along with Hamilton’s extended principle is used to obtain two second-order nonlinear ordinary-differential equations of motion and associated boundary conditions. Then, the method of multiple scales is applied to obtain a set of four first-order nonlinear ordinary-differential equations governing the modulation of the amplitudes and phases of the two excited modes. For the case of subcombination resonance, the method of multiple scales is applied directly to the Lagrangian and virtual-work term. Then using Hamilton’s extended principle, we obtain a set of four first-order nonlinear ordinary-differential equations governing the amplitudes and phases of the two excited modes. In both cases, the modulation equations are used to generate frequency- and force-response curves. We found that the trivial solution exhibits a jump as it undergoes a subcritical pitchfork bifurcation. Similarly, the nontrivial solutions also exhibit jumps as they undergo saddle-node bifurcations.

Perturbation Analysis and Chaotic Dynamics of Rotating Blade With Varying Angular Speed

2011 ◽  
Author(s):  
Yan-ping Chen ◽  
Ming-Hui Yao ◽  
Wei Zhang ◽  
Qian Wang
Keyword(s):  
Differential Equations ◽  
Perturbation Analysis ◽  
Chaotic Dynamics ◽  
Multiple Scales ◽  
Angular Speed ◽  
Aerodynamic Load ◽  
Chaotic Motions ◽  
Rotating Speed ◽  
Rotating Blade ◽  
Averaged Equations

Perturbation analysis and chaotic dynamics of the rotating blade with varying angular speed are investigated. Centrifugal force, aerodynamic load and the perturbed angular speed due to the inconstant air velocity are considered. The rotating blade is treated as a pre-twist, presetting, thin-walled rotating cantilever beam. The nonlinear governing partial differential equations of the varying angular rotating blade are established by using Hamilton’s principle. Then, the ordinary differential equations of the rotating blade are obtained by employing the Galerkin’s approach during which Galerkin’s modes satisfy corresponding boundary conditions. The four-dimensional nonlinear averaged equations are obtained by applying the method of multiple scales. In this paper, the resonant case is 1:2 internal resonance-1/2 subharmonic resonance. The numerical simulation is used to investigate chaotic dynamics of the varying angular rotating blade. The results show that the system is sensitive to the rotating speed and there are chaotic motions.

TORSION VIBRATION AND PARAMETRIC INSTABILITY ANALYSIS OF A SPUR GEAR SYSTEM WITH TIME-VARYING AND SQUARE NONLINEARITIES

2014 ◽  
Vol 06 (01) ◽  
pp. 1450007 ◽  
Author(s):  
WEI ZHANG ◽  
QIAN DING
Keyword(s):  
Equations Of Motion ◽  
Parametric Instability ◽  
Harmonic Balance Method ◽  
Period Doubling ◽  
Spur Gear ◽  
Gear System ◽  
System Response ◽  
Time Varying ◽  
Contact Ratio ◽  
Resonant Condition

This paper investigates the dynamics of a spur gear system with time-varying and square nonlinearities, by both analytical method and numerical simulation. First, the equations of motion of a 2 degree-of-freedom system are established and the harmonic balance method is used to analyze the stability and the steady-state response of the system under the main resonant condition. Then the perturbation method is used to analyze the parameter instability under the main, subharmonic and nonresonance conditions. Finally, the interactions between the main and subharmonic resonant amplitudes and the nonlinearity and the contact ratio are analyzed. The results reveal that the system response contains various frequency components, such as meshing frequency and its higher harmonic terms due to the nonlinearity and the time-varying stiffness. The existence of the time-varying meshing stiffness can also result in the subharmonic resonance, and even chaos through period-doubling bifurcations as the input torque increases.

Parametric Instability in a Gear Train System Due to Stiffness Variation

2013 ◽  
Author(s):  
S. Y. Wang ◽  
S. C. Sinha
Keyword(s):  
Differential Equations ◽  
Parametric Instability ◽  
Gear Train ◽  
Elastic Model ◽  
Time Varying ◽  
Ring Gear ◽  
Mesh Stiffness ◽  
Varying Coefficients ◽  
Wide Range ◽  
Stiffness Variation

The excitation from mesh stiffness variation in a tunnel gear driving system can cause excessive noise and vibrations. Since the stiffness variation may induce parametric instability, the system could be damaged on a permanent-basis. Therefore, the study of parametric instability in such system is of paramount importance. In this work, a rigid-elastic model is developed using the energy method, where the ring gear is treated as a rotating thin ring having radial and tangential deflections, whereas the pinions are assumed to be rigid bodies having translational motion relative to the radial directions of the ring gear as well as rotational motions around their centers. All gear meshes are modeled as interactions caused by time-varying springs, and the supports of the pinions are modeled as linear springs in the radial direction relative to the ring gear. The modeling leads to a set of partial-ordinary linear differential equations with time-varying coefficients. For an N planet system, the discretization process yields 2N+2 ordinary differential equations. Stability boundaries are determined using Floque’t theory for a wide range of parameter values. Specifically, the effects of mesh stiffness on the parametric instability are examined. The results show that the instability behaviors are closely related to the basic parameters when considering the time-varying excitation. This could be a serious consideration in the preliminary design of such systems.

Vibration Response and Parametric Instability in Beams With Combined Quadratic and Cubic Material Nonlinearities

1995 ◽  
Author(s):  
David Chelidze ◽  
Kambiz Farhang ◽  
Tyler J. Selstad
Keyword(s):  
Differential Equations ◽  
Boundary Conditions ◽  
Multiple Scales ◽  
Nonlinear Differential Equations ◽  
Equations Of Motion ◽  
Parametric Instability ◽  
Response Amplitude ◽  
Nonlinear Material ◽  
Mode Shapes ◽  
Cross Sectional

Abstract Parametric stability in beams with combined quadratic and cubic material nonlinearities is examined. A general mathematical model is developed for parametrically excited beams accounting for their nonlinear material characteristic. Second- and forth-order nonlinear differential equations are found to govern the axial and transverse motions, respectively. Expansions for displacements are assumed in terms of the linear undamped free-oscillation modes. Boundary conditions are applied to the expansions for displacements to determine the mode shapes. Multiplying the equations of motion by the corresponding shape functions, accounting for their orthogonal properties, and integrating over the beam length, a set of coupled nonlinear differential equations in the time-dependent modal coefficients is obtained. Utilizing the method of multiple scales, frequency response as well as response versus excitation amplitude are obtained for two beams of different cross sectional areas. Results are presented for three boundary conditions. It is found that, qualitatively, the response is similar for all the boundary conditions. Quantitative comparison of the cases considered indicate that the highest response amplitude occurs for the cantilever beam with the end mass. The bifurcation points for simply supported beam occur at lower excitation parameter value. It is apparent that more slender columns have larger response amplitude.

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