Study on Vibration Characteristics of High-Speed Rotating Constrained Blades Based on Spin Softening

2017 ◽  
Vol 863 ◽  
pp. 241-245
Author(s):  
Hui Ying Zhao ◽  
Xiu Hua Men
Keyword(s):  
Dynamic Model ◽  
Mode Shape ◽  
High Speed ◽  
Engineering Application ◽  
Rotor Dynamics ◽  
Vibration Characteristics ◽  
Blade Vibration ◽  
Rotating Blades ◽  
Rotating Blade ◽  
Optimal Designing

Based on the theories of rotor dynamics, a dynamic model of rotating blade was built. Taking account of the effect of spin softening, the research on vibration characteristics of high-speed rotating blades was carried out under different speeds. The results had shown that frequency of blade vibration increased with rising rotating velocity, whilst the frequency of all orders declined with the influence of spin softening. Meanwhile, the change of each mode shape of blade was not very large at different speed. The conclusion derived from this paper had both theoretical and empirical value on retrofitting, optimal-designing, as well as engineering application for high-speed rotating blades.

Analysis of Vibration Characteristics of Friction Plate Based on Rigid-Flexible Coupling Model

2013 ◽  
Vol 572 ◽  
pp. 480-484
Author(s):  
Shen Long Li ◽  
Jiang Li Pan ◽  
Hua Bing Yin
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Element Model ◽  
Coupling Model ◽  
Vibration Characteristics ◽  
Composition Analysis ◽  
Coupling Vibration ◽  
Flexible Coupling ◽  
Friction Plate ◽  
The Impact

The stability and reliability of the shift friction plate are the main condition to guarantee the normal working for the planetary gearbox. But the failures of the friction plate, such as fracture or broken plastic deformation, often appear during the real vehicle testing process. Currently, most studies focus on chemical composition analysis and fracture analysis for the fractured friction plate, but less study for shock damage. In this paper, we develop a multi-body dynamic model, a finite element model and a rigid-flexible coupling dynamic model to analyze and compare the vibration characteristics of the friction plate with three different support forms. The variation law of the impact force and frequency can be obtained for the tooth portion of the friction plate with different support forms. Finally, it can provide theoretical guidance for studying the failure of friction plate at high speed. Keywords: Friction Plate; Rigid-flexible Coupling; Vibration Characteristics

Effects of Stator Flow Distortion on Rotating Blade Endurance: Part 2—Stress Analysis and Failure Criteria

2012 ◽  
Author(s):  
Harold Simmons ◽  
Vishwas Iyengar ◽  
Timothy C. Allison
Keyword(s):  
Structural Response ◽  
Failure Criteria ◽  
Load Flow ◽  
Operating Conditions ◽  
Flow Distortion ◽  
Blade Vibration ◽  
Rotating Blades ◽  
Rotating Blade ◽  
Wide Range ◽  
Major Factors

Blade vibrations, with the possibility of failure, is one of the major factors controlling the reliability of compressors and turbines. The prospects of encountering high alternating stress environments in blades make efficient turbomachine operation a very challenging task. In many cases the compressor or turbine functions through a wide range of load, flow, temperature, and speed which affect blade vibration, thus the stress environment continuously changes as the operating conditions changes. Any flow disturbance upstream of the rotating blades and some disturbances downstream will produce repetitive wake pulses that excite the blades. Resonance occurs with any coincidence of repetitive pulses with structural natural frequencies of rotating blades or impellers resulting in substantial amplification of alternating stresses. Most OEM design practices control vibratory stresses by avoiding resonance with expected stator sources; those excitations that cannot be avoided are designed with sufficient endurance to prevent failure. Thus three aspects of rotor/ blade design affect reliability: 1) aerodynamic excitation level and frequency, 2) structural response and resonance margins, and 3) selection and control of materials, coatings and their fabrication process to withstand the service environment. The main objective of this study is to develop a mathematical model to simulate the stresses in the rotating blade row that evaluates all three aspects of design to assess long term endurance. This is a two part paper on high cycle fatigue (HCF) failure analysis procedure of rotating blades and impellers. Part 1 [1] discusses aerodynamic excitation caused by stator vane and its role in generation of blade vibration. Here comprehensive computational fluid dynamics (CFD) is used to get a better understanding of the stator-rotor flow interactions at different operating conditions. The results of the aerodynamic simulations are order related excitation spectrum that can be applied to the stress/pulsation relationship defined in this part of the paper. This paper, Part 2, discusses an empirical dynamic stress model developed by impulse testing, assessing material endurance strength, and evaluation of criteria for failure by HCF.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

scholarly journals Investigating the Trackability of Silicon Microprobes in High-Speed Surface Measurements

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1557
Author(s):  
Min Xu ◽  
Zhi Li ◽  
Michael Fahrbach ◽  
Erwin Peiner ◽  
Uwe Brand
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
High Signal ◽  
Resonant Response ◽  
High Demand ◽  
Surface Measurements ◽  
Tactile Roughness ◽  
Low Mass ◽  
Roughness Measurements

High-speed tactile roughness measurements set high demand on the trackability of the stylus probe. Because of the features of low mass, low probing force, and high signal linearity, the piezoresistive silicon microprobe is a hopeful candidate for high-speed roughness measurements. This paper investigates the trackability of these microprobes through building a theoretical dynamic model, measuring their resonant response, and performing tip-flight experiments on surfaces with sharp variations. Two microprobes are investigated and compared: one with an integrated silicon tip and one with a diamond tip glued to the end of the cantilever. The result indicates that the microprobe with the silicon tip has high trackability for measurements up to traverse speeds of 10 mm/s, while the resonant response of the microprobe with diamond tip needs to be improved for the application in high-speed topography measurements.

scholarly journals On Curve Veering and Flutter of Rotating Blades

1994 ◽  
Vol 116 (3) ◽  
pp. 702-708 ◽  
Author(s):  
D. Afolabi ◽  
O. Mehmed
Keyword(s):  
Algebraic Geometry ◽  
Catastrophe Theory ◽  
Algebraic Curves ◽  
Rotation Speed ◽  
Elastic Stability ◽  
Rotating Blades ◽  
Rotating Blade ◽  
Modes Of Vibration ◽  
Curve Veering ◽  
As If

The eigenvalues of rotating blades usually change with rotation speed according to the Stodola-Southwell criterion. Under certain circumstances, the loci of eigenvalues belonging to two distinct modes of vibration approach each other very closely, and it may appear as if the loci cross each other. However, our study indicates that the observable frequency loci of an undamped rotating blade do not cross, but must either repel each other (leading to “curve veering”), or attract each other (leading to “frequency coalescence”). Our results are reached by using standard arguments from algebraic geometry—the theory of algebraic curves and catastrophe theory. We conclude that it is important to resolve an apparent crossing of eigenvalue loci into either a frequency coalescence or a curve veering, because frequency coalescence is dangerous since it leads to flutter, whereas curve veering does not precipitate flutter and is, therefore, harmless with respect to elastic stability.

Rotor-Dynamics of Different Shaft Configurations for a 6 kW Micro Gas Turbine for Concentrated Solar Power

2016 ◽  
Author(s):  
A. Arroyo ◽  
M. McLorn ◽  
M. Fabian ◽  
M. White ◽  
A. I. Sayma
Keyword(s):  
Gas Turbines ◽  
High Speed ◽  
Dynamic Models ◽  
Solar Power ◽  
Critical Issue ◽  
Rotor Dynamics ◽  
Mode Shapes ◽  
Concentrated Solar Power ◽  
Element Analysis ◽  
Rotor Dynamic

Rotor-dynamics of Micro Gas Turbines (MGTs) under 30 kW have been a critical issue for the successful development of reliable engines during the last decades. Especially, no consensus has been reached on a reliable MGT arrangement under 10 kW with rotational speeds above 100,000 rpm, making the understanding of the rotor-dynamics of these high speed systems an important research area. This paper presents a linear rotor-dynamic analysis and comparison of three mechanical arrangements of a 6 kW MGT intended for utilising Concentrated Solar Power (CSP) using a parabolic dish concentrator. This application differs from the usual fuel burning MGT in that it is required to operate at a wider operating speed range. The objective is to find an arrangement that allows reliable mechanical operation through better understanding of the rotor dynamics for a number of alternative shaft-bearings arrangements. Finite Element Analysis (FEA) was used to produce Campbell diagrams and to determine the critical speeds and mode shapes. Experimental hammer tests using a new approach based on optical sensing technology were used to validate the rotor-dynamic models. The FEA simulation results for the natural frequencies of a shaft arrangement were within 5% of the measurements, while the deviation for the shaft-bearings arrangement increased up to 16%.

Analysis of Rotating Blade Forced Vibration Due to Torsional Excitation Using the Method of Harmonic Balance

2002 ◽  
Author(s):  
B. O. Al-Bedoor ◽  
A. A. Al-Qaisia
Keyword(s):  
Forced Vibration ◽  
Harmonic Balance ◽  
Approximate Solutions ◽  
Coefficient Matrix ◽  
Blade Vibration ◽  
Varying Coefficients ◽  
Rotating Blade ◽  
Method Of Harmonic Balance ◽  
Torsional Excitation ◽  
Truncated Fourier Series

This paper presents an analysis of the forced vibration of rotating blade due to torsional excitation. The model analyzed is a multi-modal forced second order ordinary differential equation with multiple harmonically varying coefficients. The method of Harmonic Balance (HB) is employed to find approximate solutions for each of the blade modes in the form of truncated Fourier series. The solutions have shown multi resonance response for the first blade vibration mode. The examination of the determinant of the harmonic balance solution coefficient matrix for stability purposes has shown that the region between the two resonance points is an unstable vibration region. Numerical integration of the equations is conducted at different frequency ratio points and the results are discussed. This solution provides a very critical operation and design guidance for rotating blade with torsional vibration excitation.

Improvement and Lock Calculation of Electric Switch Machine of Railway Turnout

2013 ◽  
Vol 409-410 ◽  
pp. 1496-1501 ◽  
Author(s):  
Jing Mang Xu ◽  
Ping Wang ◽  
Hao Xu
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Lateral Stiffness ◽  
High Speed Railway ◽  
Train Speed ◽  
Working Status ◽  
Stress And Deformation ◽  
Railway Turnout

Electric switch machine locks the crossing rail in the working direction and checks the working status of the crossing. With the increase of train speed, the ZD(J)9 electric switch machine cant satisfy the equipment of high speed railway, This paper studied the optimization; in order to study the lock calculation of nose rail after conversion, a dynamic model is established to research the influence of working status of the crossing. It indicates that for the first traction point, the stress and deformation are mainly affected by scant displacement between nose rail and wing rail; for the second traction point, they are affected by the gap between nose rail and spacer; fastener lateral stiffness doesnt influence the stress status, but the lateral fastener stiffness should not be too small.

Sign in / Sign up

Export Citation Format

Share Document