Mistuning and Structural Coupling Effects on Flutter of Turbomachinery Blades

A fast numerical method based on aeroelastic eigenvalue analysis is applied to study the effects of mistuning on the aeroelastic stability of turbomachinery blades in which the structural coupling is included by a simplified method and an influence coefficient method is employed to deal with the unsteady aerodynamic effects. Results show that there exists an optimal mistuning amount at which the system has the best aeroelastic stability. Structural coupling almost has no effects on aeroelastic stability of a tuned system. But the benefit of alternate frequency mistuning to aeroelastic stability is inhibited drastically when structural coupling is introduced into the bladed disk system.

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Influence Coefficients Obtained by Hammer Beat Permit Significant Time Savings When Balancing Simple Flexible Rotors

Volume 7A: 17th Biennial Conference on Mechanical Vibration and Noise ◽

10.1115/detc99/vib-8260 ◽

1999 ◽

Author(s):

D. Wiese ◽

M. Breitwieser

Keyword(s):

Influence Coefficient ◽

Significant Time ◽

Flexible Rotors ◽

Influence Coefficients ◽

Flexible Roll ◽

Influence Coefficient Method ◽

Time Savings ◽

Positive Results ◽

Coefficient Method

Abstract The following paper presents a method for balancing simple flexible rotors with the help of influence coefficients obtained by hammer beat. The method permits time savings of approx. 50% compared to the conventional influence coefficient method. Initial positive results obtained on a flexible roll are also presented.

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Study on the Applicability of Influence Coefficient Method Combined with Vector Analysis in Dynamic Balancing Rigid Rotor Using Flexible Supports

2018 4th International Conference on Green Technology and Sustainable Development (GTSD) ◽

10.1109/gtsd.2018.8595685 ◽

2018 ◽

Cited By ~ 1

Author(s):

Lam Tran Thanh ◽

Ngon Dang Thien ◽

Cuong Le Chi

Keyword(s):

Vector Analysis ◽

Influence Coefficient ◽

Rigid Rotor ◽

Dynamic Balancing ◽

Flexible Supports ◽

Influence Coefficient Method ◽

Coefficient Method

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Prototype design and size optimization of a hybrid lower extremity exoskeleton with a scissor mechanism for load-carrying augmentation

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406214532078 ◽

2014 ◽

Vol 229 (1) ◽

pp. 155-167 ◽

Cited By ~ 4

Author(s):

Yunjie Miao ◽

Feng Gao ◽

Dalei Pan

Keyword(s):

Lower Extremity ◽

Influence Coefficient ◽

Input And Output ◽

Flexion Extension ◽

Load Carrying ◽

Influence Coefficient Method ◽

Prototype Design ◽

Coefficient Method ◽

Length Optimization ◽

Scissor Mechanism

A hybrid lower extremity exoskeleton SJTU-EX which adopts a scissor mechanism as the hip and knee flexion/extension joint is proposed in Shanghai Jiao Tong University to augment load carrying for walking. The load supporting capabilities of a traditional serially connected mechanism and the scissor mechanism are compared in detail. The kinematic influence coefficient method of the kinematic and dynamic analysis is applied in the length optimization of the scissor sides to minimize the transmitting errors between the input and output motions in walking and the load capacities of different scissor mechanisms are illustrated. The optimization results are then verified by the walking simulations. Finally, the prototype of SJTU-EX is implemented with several improvements to enhance the working performances.

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Free Vibration Analysis of a Structure with Closed Loops by the Transfer Influence Coefficient Method

Journal of System Design and Dynamics ◽

10.1299/jsdd.1.374 ◽

2007 ◽

Vol 1 (2) ◽

pp. 374-385

Author(s):

Takumi INOUE ◽

Atsuo SUEOKA

Keyword(s):

Free Vibration ◽

Vibration Analysis ◽

Free Vibration Analysis ◽

Influence Coefficient ◽

Closed Loops ◽

Influence Coefficient Method ◽

Coefficient Method

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Study on an Intelligent Teaching Dynamic Balance Technology

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.483.174 ◽

2013 ◽

Vol 483 ◽

pp. 174-176 ◽

Cited By ~ 1

Author(s):

Shu Ping Cai ◽

Ting Zhao

Keyword(s):

Dynamic Balance ◽

Far Infrared ◽

Test System ◽

Influence Coefficient ◽

Dynamic Balancing ◽

Influence Coefficient Method ◽

Sensitive Sensor ◽

Phase Sensor ◽

Electric Measuring ◽

Coefficient Method

Abstract:.:Intelligent teaching Dynamic balancing is a new kind of dynamic balancing test system with various functions of teaching need. It integrates the hard bearing method using A, B, C size solution with soft bearing method using the influence coefficient method solution. The system is mainly composed of machine frame, intelligent electric measuring box, high sensitive sensor and far infrared phase sensor. It has the advantages of small volume, simple operation, security with low speed，reliable and convenient operation for students. It can deepen students' understanding of balancing knowledge, which has won the national utility model patent.

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Research on Dynamics of a Three-DOF Parallel Manipulator for Levelling Mechanism

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.774-776.1369 ◽

2013 ◽

Vol 774-776 ◽

pp. 1369-1374 ◽

Cited By ~ 1

Author(s):

Hong Jun Yang

Keyword(s):

Parallel Manipulator ◽

Coefficient Matrix ◽

Dynamics Simulation ◽

Dynamic Equations ◽

Control System Design ◽

Influence Coefficient ◽

Lagrange Method ◽

First Order ◽

Influence Coefficient Method ◽

Coefficient Method

A three-DOF parallel manipulator with two rotations and one translation was put forward as a levelling mechanism in this paper. Its structure and kinematics were analyzed and the first-order influence coefficient matrix was obtained by using the influence coefficient method. Then the complete and concise dynamic equations without too many unknowns were established based on Lagrange method. In addition, the dynamics simulation was carried out and the result shows that drive forces of the legs have no strong coupling, which is important to control system design.

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Analysis and Control of the 1st Order Interior Noise and Vibration Induced by Driveline Imbalance for 4WD Vehicle

Volume 4B: Dynamics, Vibration, and Control ◽

10.1115/imece2016-65427 ◽

2016 ◽

Author(s):

Yuanfeng Xia ◽

Jian Pang ◽

Rui Liu ◽

Wenjuan Li ◽

Jianchun Xu

Keyword(s):

The Body ◽

Influence Coefficient ◽

Vehicle Interior ◽

Single Plane ◽

Acoustic Cavity ◽

Testing Method ◽

Sensitivity Theory ◽

Influence Coefficient Method ◽

And Control ◽

Coefficient Method

Based on the influence coefficient method of the single-plane and multi-plane imbalance, an experimental method of a 4WD driveline system imbalance is proposed. A sensitivity theory and a testing method of influence of the 4WD driveline system imbalance on the vehicle interior 1st order vibration and noise are proposed. According to the influence coefficient method of the single plane, this paper puts forward an imbalance separation method for the driveline components, especially the imbalance separation between the driveshaft and the axle. Based on the problems and phenomena of the 1st order interior vibration and noise induced by the driveline imbalance transferring through the body floor and the interior acoustic cavity, the driveline imbalance sensitivity, the dynamic imbalance of the driveshaft and the driveline system are analyzed separately. Finally, the control methods of the dynamic imbalance and sensitivity of the 4WD vehicle driveline system are provided.

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Unsteady Aerodynamic Characteristics of Oscillating Cascade With Separation Bubble in High Subsonic Flow

Volume 4: Turbo Expo 2005 ◽

10.1115/gt2005-68665 ◽

2005 ◽

Cited By ~ 3

Author(s):

Toshinori Watanabe ◽

Mizuho Aotsuka

Keyword(s):

Subsonic Flow ◽

Separation Bubble ◽

Leading Edge ◽

Aerodynamic Characteristics ◽

Influence Coefficient ◽

Unsteady Aerodynamic ◽

Key Factor ◽

Influence Coefficient Method ◽

Airfoil Blades ◽

High Subsonic Flow

Unsteady aerodynamic characteristics of an oscillating cascade composed of DCA (Double Circular Arc airfoil) blades were studied both experimentally and numerically. The test cascade was operated in high subsonic flow fields with incidence angles up to 5 degrees. Above 3 degrees of the incidence, a separation bubble was produced at the leading edge. The principal concern of the present study was placed on the influence of the separated region on the vibration instability of the cascade blades. The experiment was conducted in a linear cascade wind tunnel in which seven DCA blades were equipped. The central one could be oscillated in a pitching mode. The influence coefficient method was adopted for the measurement, where the unsteady aerodynamic moments were measured on the central blade and neighboring ones. For the numerical analysis, a quasi 3-D N-S code with k–ε turbulence model was developed. The experimental and numerical results complemented each other to obtain detailed understanding of the unsteady aerodynamic behavior of the cascade. It was found that the separation bubble at the leading edge governed the vibration characteristics of blades through the oscillation of the separation bubble itself on the blade surfaces. From the results of parametric studies, the phase shift of the oscillation of the separation bubble was found to be a key factor for determining the unsteady aerodynamic characteristics of the oscillating blades.

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