Steady-State Residual Vibrations in High-Speed, Dwell-Type, Rotating Disk Cam-Follower Systems

2005 ◽  
Vol 127 (1) ◽  
pp. 12-17 ◽  
Author(s):  
Stephen F. Felszeghy
Keyword(s):  
Steady State ◽  
High Speed ◽  
Transient Analysis ◽  
Linear Models ◽  
Initial Conditions ◽  
Rotating Disk ◽  
Residual Vibration ◽  
Transient Vibration ◽  
Closed Form Solutions ◽  
Cam Follower

Followers driven by high-speed, dwell-type, rotating disk cams can exhibit undesirable residual vibrations during dwell. These vibrations have been studied with linear models mostly using results from transient vibration analysis, assuming quiescent initial conditions. Here, the residual vibrations are studied with closed-form solutions to the steady-state vibrations obtained with a circular convolution integral. The steady-state vibrations, which can extend over the entire cam cycle, are periodic and continuous. It is shown that significant differences exist between the residual vibration results obtained from steady-state analysis and those obtained from transient analysis. The undamped steady-state vibrations exhibit resonances. Away from the resonance conditions, the steady-state residual vibration amplitudes are consistently smaller than those predicted by transient analysis. The results from the two approaches agree quantitatively only for relatively stiff and damped follower systems.

Squeeze film dampers supporting high-speed rotors: Rotordynamics

2020 ◽  
pp. 135065012092208
Author(s):  
Sina Hamzehlouia ◽  
Kamran Behdinan
Keyword(s):  
Finite Element ◽  
Steady State ◽  
Gas Turbines ◽  
High Speed ◽  
Squeeze Film ◽  
Jet Engines ◽  
Transient Vibration ◽  
Element Analysis ◽  
Squeeze Film Damper ◽  
The Time Domain

This work develops a finite element based multi-mass flexible rotor model for theoretical investigation of the influence of the squeeze film damper lubricant inertia on the unbalance-induced steady-state and transient vibration amplitudes of high speed turbomachinery. The rotordynamic model is developed by applying the principles of finite element analysis to discretize the rotor components, including the rotor shaft and disk, into local elements with mass, stiffness, and gyroscopic matrices. Subsequently, the local matrices are assembled together to develop the global model of the rotordynamic system. The influence of squeeze film damper lubricant inertia is incorporated into the model by using short-length cavitated damper models with retaining springs executing circular-centered orbits. Additionally, the rotordynamic model incorporating the nonlinear squeeze film damper models is iteratively solved in the time domain by applying a predictor-corrector transient modal integration numerical method and the steady-state and transient motions of the rotor system are investigated under different rotor and squeeze film damper parameters. The results of the study verify the substantial influence of squeeze film damper lubricant inertia on attenuating the vibrations of high-speed turbomachinery. Furthermore, the developed rotordynamic model delivers an efficient and powerful platform for the analysis of high-speed turbomachinery, including jet engines and gas turbines.

Synthesis and Steady State Analysis of High-Speed Elastic Cam-Follower Linkages With Concentrated Masses: Part II — Steady State Analysis

1991 ◽  
Author(s):  
Hsin-Ting J. Liu ◽  
Donald R. Flugrad
Keyword(s):  
Steady State ◽  
High Speed ◽  
Steady State Response ◽  
Steady State Analysis ◽  
State Response ◽  
Periodic Linear ◽  
Cam Follower ◽  
Concentrated Masses ◽  
Characteristic Multipliers ◽  
State Analysis

Abstract The responses for different design and simulation conditions, including various speed and damping ratios, are investigated for an elastic cam-follower system discussed in Part I. The location of a single dominant pair of characteristic multipliers of the inhomogeneous periodic linear system is found to have significant influence on the steady state response.

Designing Dynamically Compensated and Robust Cam Profiles With Bernstein-Bézier Harmonic Curves

1997 ◽  
Author(s):  
Lakshmi N. Srinivasan ◽  
Q. Jeffrey Ge
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Vibration Characteristics ◽  
Resonant Vibrations ◽  
Residual Vibration ◽  
Numerical Examples ◽  
Polynomial Curves ◽  
Harmonic Content ◽  
Cam Follower ◽  
Design Speed

Abstract This paper deals with the problem of designing dynamically compensated cam profiles to minimize residual vibrations in high-speed cam-follower systems. The traditional Polydyne method is modified and extended to achieve significant improvement in residual vibration characteristics. First, cam displacement curves are represented by Bernstein-Bézier harmonic curves as opposed to polynomial curves. These recently developed harmonic curves are low in harmonic content and therefore the resulting cam profiles are less prone to induce resonant vibrations in the follower system. Second, the design procedure is expanded such that the residual vibrations of the resulting cam-follower system is not only extinguished at the design speed but also made insensitive to speed variations. Numerical examples are given in the end.

Designing Dynamically Compensated and Robust Cam Profiles With Bernstein-Be´zier Harmonic Curves

1998 ◽  
Vol 120 (1) ◽  
pp. 40-45 ◽  
Author(s):  
L. N. Srinivasan ◽  
Q. Jeffrey Ge
Keyword(s):  
High Speed ◽  
Design Procedure ◽  
Vibration Characteristics ◽  
Resonant Vibrations ◽  
Residual Vibration ◽  
Numerical Examples ◽  
Polynomial Curves ◽  
Harmonic Content ◽  
Cam Follower ◽  
Design Speed

This paper deals with the problem of designing dynamically compensated cam profiles to minimize residual vibrations in high-speed cam-follower systems. The traditional Polydyne method is modified and extended to achieve significant improvement in residual vibration characteristics. First, cam displacement curves are represented by Bernstein-Be´zier harmonic curves as opposed to polynomial curves. These recently developed harmonic curves are low in harmonic content and therefore the resulting cam profiles are less prone to induce resonant vibrations in the follower system. Second, the design procedure is expanded such that the residual vibrations of the resulting cam-follower system is not only extinguished at the design speed but also made insensitive to speed variations. Numerical examples are given in the end.

Synthesis and Steady State Analysis of High-Speed Elastic Cam-Follower Linkages With Concentrated Masses: Part I — Theory

1991 ◽  
Author(s):  
Hsin-Ting J. Liu ◽  
Donald R. Flugrad
Keyword(s):  
Steady State ◽  
Iterative Procedure ◽  
High Speed ◽  
Linear Ordinary Differential Equations ◽  
Periodic Linear ◽  
Cam Follower ◽  
Cam Profile ◽  
Concentrated Masses ◽  
Design Speed ◽  
Steady State Solutions

Abstract A cam driving a lumped inertia through a massless, elastic, slider-crank follower linkage with two concent rated masses located at the pin joints is considered. An iterative procedure taking the elasticity, damping, and changing geometry of the linkage into account is developed for synthesizing the cam profile to produce a desired output motion at a given design speed. The steady state solutions for the inhomogeneous, periodic, linear, ordinary differential equations are solved numerically by Hsu’s method.

The Dynamic Analysis of High-Speed Energy Storage Flywheel Rotor System

2013 ◽  
Vol 770 ◽  
pp. 78-83
Author(s):  
Xiu Hua Zhang ◽  
Guang Xi Li ◽  
Long Nie
Keyword(s):  
Steady State ◽  
Energy Storage ◽  
High Speed ◽  
Transient Analysis ◽  
Critical Speed ◽  
Large Scale ◽  
Simulation Analysis ◽  
Rotor System ◽  
Analysis Method ◽  
Flywheel Rotor

This article aims at large-scale energy storage flywheel rotor system, obtaining the dynamic characteristics. Through theoretical analysis, and after doing a simulation analysis for a given flywheel rotor on the 0-20000 RPM, getting the flywheel rotor critical speed, the transient analysis and imbalance response. The system is in steady state at runtime according to the analysis results. Providing also certain theory basis for study of flywheel rotor system according to the analysis method .

Semi-Analytical Dynamic Analysis of Noncontacting Finger Seals

2015 ◽  
Vol 15 (04) ◽  
pp. 1450060 ◽  
Author(s):  
Kaibing Du ◽  
Yongjian Li ◽  
Shuangfu Suo ◽  
Yuming Wang
Keyword(s):  
Steady State ◽  
Initial Conditions ◽  
Dynamic Properties ◽  
Dynamic Performance ◽  
Equations Of Motion ◽  
Analytical Form ◽  
Closed Form Solutions ◽  
Fully Adaptive ◽  
Steady State Responses ◽  
Analytical Dynamic

Noncontacting finger seals represent a new noncontacting and compliant seal in gas turbine sealing technology. The compliance and noncontacting nature make this kind of seals fully adaptive to rotor excursions in the radial direction without damaging the seal performance. A new semi-analytical method is developed for characterizing the linearized dynamic performance of noncontacting finger seals. The linearized dynamic characteristics of the gas film are numerically computed using the step jump method and then approximated analytically in the equations of motion using a Prony series. By combining the gas film analytical dynamic characterization with the constitutive model for the dynamic properties of noncontacting finger seals, the dynamic equation of motion for the system is derived in analytical form. The results are presented of the gas film properties, natural transient response to initial conditions, steady-state response to rotor excursion, transmissibility ratios and dynamic stability analysis using the analytical model. It is demonstrated that the steady-state responses from the closed-form solutions agree well with those by the numerical simulation, and the analytical solutions can be used as the benchmark for calibrating the results from numerical analysis.

High-Speed Imaging to Study an Auto-Oscillating Vocal Fold Replica for Different Initial Conditions

2017 ◽  
Vol 09 (05) ◽  
pp. 1750064 ◽  
Author(s):  
A. Van Hirtum ◽  
X. Pelorson
Keyword(s):  
Vocal Fold ◽  
High Speed ◽  
Initial Conditions ◽  
Vocal Folds ◽  
High Speed Imaging ◽  
Human Voice ◽  
Manual Intervention ◽  
Geometrical Features ◽  
Upstream Pressure

Experiments on mechanical deformable vocal folds replicas are important in physical studies of human voice production to understand the underlying fluid–structure interaction. At current date, most experiments are performed for constant initial conditions with respect to structural as well as geometrical features. Varying those conditions requires manual intervention, which might affect reproducibility and hence the quality of experimental results. In this work, a setup is described which allows setting elastic and geometrical initial conditions in an automated way for a deformable vocal fold replica. High-speed imaging is integrated in the setup in order to decorrelate elastic and geometrical features. This way, reproducible, accurate and systematic measurements can be performed for prescribed initial conditions of glottal area, mean upstream pressure and vocal fold elasticity. Moreover, quantification of geometrical features during auto-oscillation is shown to contribute to the experimental characterization and understanding.

Steady-State Dynamic Response of a Limited Slip System

1968 ◽  
Vol 35 (2) ◽  
pp. 322-326 ◽  
Author(s):  
W. D. Iwan
Keyword(s):  
Steady State ◽  
Dynamic Response ◽  
Slip System ◽  
External Load ◽  
Initial Conditions ◽  
Viscous Damping ◽  
Steady State Response ◽  
Response Curves ◽  
State Response ◽  
System Nonlinearity

The steady-state response of a system constrained by a limited slip joint and excited by a trigonometrically varying external load is discussed. It is shown that the system may possess such features as disconnected response curves and jumps in response depending on the strength of the system nonlinearity, the level of excitation, the amount of viscous damping, and the initial conditions of the system.

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