scholarly journals Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Nailu Li ◽  
Mark J. Balas ◽  
Hua Yang ◽  
Wei Jiang ◽  
Kaman T. Magar
Keyword(s):  
Torsional Vibration ◽  
Numerical Data ◽  
Vibration Modes ◽  
Aerodynamic Model ◽  
Aeroelastic Model ◽  
Vibration Model ◽  
Divergence Instability ◽  
Blade Section ◽  
Control Capability ◽  
Control Study

This study presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instability case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.

Numerical Investigation on the Selection of the System Outputs for Feedback Vibration Control of a Smart Blade Section

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Nailu Li ◽  
Mark J. Balas ◽  
Hua Yang ◽  
Wei Jiang
Keyword(s):  
Vibration Control ◽  
Feedback System ◽  
Vibration Modes ◽  
Torsional Mode ◽  
Aerodynamic Model ◽  
Attached Flow ◽  
Blade Section ◽  
Section Model ◽  
Effective Output ◽  
Equations Of Motions

This study presents the possible and effective output signals for the feedback vibration control of the smart blade section undergoing different aerodynamic conditions. Equations of motions of the smart blade section are described by a typical wing section model, leading to three vibration modes (flapwise mode, edgewise mode, and torsional mode). The aerodynamics is described by an unsteady aerodynamic model and aerodynamic effects of the microtab installed on the trailing-edge of the blade section. The equations of the aeroservoelastic model are summarized into state-space equation for analysis of output choice in the feedback system. All vibration modes are proved to be fully controllable with the microtab actuation. The numerical results show that the most effective output signal is the combination of flapwise velocity and torsional velocity for the system undergoing the attached flow and the combination of all three-mode velocities for the system undergoing the stall flow. In addition, the output choice for different microtab configurations is also analyzed. The effectiveness of the proposed output signals in vibration control is confirmed by the simulation results.

Dynamic Modeling of the Torsional Vibration of the Slewing Mechanism of a Hydraulic Excavator

2012 ◽  
Vol 253-255 ◽  
pp. 2102-2106 ◽  
Author(s):  
Xu Juan Yang ◽  
Zong Hua Wu ◽  
Zhao Jun Li ◽  
Gan Wei Cai
Keyword(s):  
Torsional Vibration ◽  
Natural Frequencies ◽  
Planetary Gear ◽  
Moment Of Inertia ◽  
Hydraulic Excavator ◽  
Planetary Gear Trains ◽  
Vibration Model ◽  
Gear Trains ◽  
The Moment ◽  
Relationship Of

A torsional vibration model of the slewing mechanism of a hydraulic excavator is developed to predict its free vibration characteristics with consideration of many fundamental factors, such as the mesh stiffness of gear pairs, the coupling relationship of a two stage planetary gear trains and the variety of moment of inertia of the input end caused by the motion of work equipment. The natural frequencies are solved using the corresponding eigenvalue problem. Taking the moment of inertia of the input end for example to illustrate the relationship between the natural frequencies of the slewing mechanism and its parameters, based on the simulation results, just the first order frequency varies significantly with the moment of inertia of the input end of the slewing mechanism.

scholarly journals Gust Response Analysis for Helicopter Rotors in the Hover and Forward Flights

2017 ◽  
Vol 2017 ◽  
pp. 1-20 ◽  
Author(s):  
Linpeng Wang ◽  
Yuting Dai ◽  
Chao Yang
Keyword(s):  
Shear Force ◽  
Thrust Force ◽  
Vertical Direction ◽  
Beam Theory ◽  
Response Analysis ◽  
Forward Flight ◽  
Helicopter Rotors ◽  
Aerodynamic Model ◽  
Aeroelastic Model ◽  
The Time Domain

Dynamic load due to gust for helicopter rotors directly affects the structural stress and flight performance. In case of gust, it may cause the loss of trust force or the increase of deflection for rotors. In current work, an effective coupled aeroelastic model based on a medium-deflection beam theory and a nonlinear unsteady aerodynamic model in the time domain were constructed. Three types of gust in vertical direction were added in the model. The dynamic response and structural load for helicopter rotors under three types of gust were calculated, respectively. Results indicated that when rotors suffer a gust in hover at downward direction, the thrust force on rotor disk would decrease significantly when the gust amplitude increases, which should be paid attention in the design. Among the three gust types with the same gust strength, the maximum instantaneous shear force due to impulse shape gust is the largest. When the rotors suffer a gust in a forward flight, the shear force at the root of rotors would increase with the gust strength first but then it decreases. More attention should be paid to the decrease of thrust force and the increase of structural load in a forward flight.

Torsional Vibrations of Shells of Revolution

1961 ◽  
Vol 28 (4) ◽  
pp. 571-573 ◽  
Author(s):  
H. Garnet ◽  
M. A. Goldberg ◽  
V. L. Salerno
Keyword(s):  
Differential Equation ◽  
Governing Equation ◽  
Torsional Vibration ◽  
Conical Shell ◽  
Order Differential Equation ◽  
Annular Plate ◽  
Thin Shells ◽  
Torsional Vibrations ◽  
Vibration Modes ◽  
Shells Of Revolution

Torsional-vibration modes are uncoupled from the bending and extensional modes in thin shells of revolution. The solution for the uncoupled torsional modes then depends upon a linear second-order differential equation. The governing equation is subsequently solved for the frequencies of a conical shell. A tabulation of the first five frequencies for varying ratios of the terminal radii is presented. These frequencies are identical to those of an annular plate which has the same supports as the conical shell.

Multi Objective Optimization of Parameters of Torsional Vibration Dampers Considering Damping Effect and Light Weight Design

2019 ◽  
Vol 11 (1) ◽  
Author(s):  
Can Yang ◽  
Xiaodong Tan ◽  
Lin Hua ◽  
Chihua Lu ◽  
Yongliang Wang ◽  
...  
Keyword(s):  
Torsional Vibration ◽  
Degrees Of Freedom ◽  
Power Transmission ◽  
Lightweight Design ◽  
Two Stage ◽  
Damping Effect ◽  
Vibration Model ◽  
Weight Design ◽  
Elastic Couplings ◽  
Vibration Dampers

To reduce the torsional vibration of vehicle power transmission system (VPTS), a torsional vibration model with multiple degrees of freedom (MDOF) of VPTS was established. The scheme of equipping torsional vibration dampers (TVDs) on the drive shaft was employed by the calculation of the forced vibration and the free vibration of the VPTS. The energy method was used to optimize the parameters of single-stage, two-stage parallel, and two-stage series TVDs based on the principle that balances the damping effect and lightweight design. On the basis of this, the parameters of the models incorporating TVD and elastic couplings (ECs) were optimized. Results showed that the proposed method can ensure the damping effects of TVD and realize the lightweight.

scholarly journals Parametric whirl flutter study using different modelling approaches

2021 ◽  
Author(s):  
Christopher Koch
Keyword(s):  
Unsteady Aerodynamics ◽  
Beam Model ◽  
Electric Motors ◽  
Aeroelastic Stability ◽  
Aerodynamic Model ◽  
Lifting Surface ◽  
Aeroelastic Model ◽  
Strip Theory ◽  
Engine Mount ◽  
Whirl Flutter

AbstractThis paper demonstrates the importance of assessing the whirl flutter stability of propeller configurations with a detailed aeroelastic model instead of local pylon models. Especially with the growing use of electric motors for propulsion in air taxis and commuter aircraft whirl flutter becomes an important mode of instability. These configurations often include propeller which are powered by lightweight electric motors and located at remote locations, e.g. the wing tip. This gives rise to an aeroelastic instability called whirl flutter, involving the gyroscopic whirl modes of the engine. The driving parameters for this instability are the dynamics of the mounting structure. Using a generic whirl flutter model of a propeller at the tip of a lifting surface, parameter studies on the flutter stability are carried out. The aeroelastic model consists of a dynamic MSC.Nastran beam model coupled with the unsteady ZAERO ZONA6 aerodynamic model and strip theory for the propeller aerodynamics. The parameter studies focus on the influence of different substructures (ranging from local engine mount stiffness to global aircraft dynamics) on the aeroelastic stability of the propeller. The results show a strong influence of the level of detail of the aeroelastic model on the flutter behaviour. The coupling with the lifting surface is of major importance, as it can stabilise the whirl flutter mode. Including wing unsteady aerodynamics into the analysis can also change the whirl flutter behaviour. This stresses the importance of including whirl flutter in the aeroelastic stability analysis on aircraft level.

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