Modeling and Control of a Morphing Airfoil

2003 ◽  
Author(s):  
Christopher E. Whitmer ◽  
Atul G. Kelkar ◽  
Phuc Vu ◽  
Frank R. Chavez
Keyword(s):  
Finite Element ◽  
Dynamic Model ◽  
Structural Model ◽  
Linear Time ◽  
Mode Shapes ◽  
Morphing Wing ◽  
Structural Dynamic ◽  
Finite Dimensional ◽  
Aeroelastic Model ◽  
And Control

This paper presents aeroelastic modelling and robust control design for a morphing airfoil concept. A finite dimensional linear time invariant aeroelastic model is developed for a multi-input multi-output morphing airfoil structure. The shape of the airfoil (NACA airfoil series 2415) is controlled by actuators distributed along the top airfoil surface that produce vertical deflections of the top surface at several locations. This results in an airfoil shape change (i.e., “morphing” of the wing), which causes changes in the aerodynamic loading on the wing. The objective is to control the deformation of the airfoil in realtime so as to achieve the desirable aerodynamic forces on the wing. The structural model is developed using the finite element approach. A finite element toolbox in Matlab, namely FEMLAB, is used to obtain eigenfrequencies and mode shapes. A finite dimensional dynamic model of the structure is obtained by the assumed modes method. A static aerodynamic model is developed with a vortex lattice method and coupled with the structural dynamic model to yield a linear aeroelastic model of the morphing wing. A robust LQG design is presented for tracking the commanded lift and roll moment. Some parametric studies are also presented for the choice of different materials. Simulation results are given to demonstrate the viability of the proposed modelling and control methodology for morphing wing concept.

Forced Response Assessment Using Modal Force Based Indicator Functions

2008 ◽  
Author(s):  
M. Vahdati ◽  
C. Breard ◽  
G. Simpson ◽  
M. Imregun
Keyword(s):  
Finite Element ◽  
Structural Model ◽  
Stokes Equations ◽  
Linear Time ◽  
Response Assessment ◽  
Element Model ◽  
Forced Response ◽  
Navier Stokes ◽  
Modal Force ◽  
Indicator Functions

This paper will focus on core-compressor forced response with the aim to develop two design criteria, the so-called chordwise cumulative modal force and heightwise cumulative force, to assess the potential severity of the vibration levels from the correlation between the unsteady pressure distribution on the blade’s surface and the structural modeshape. It is also possible to rank various blade designs since the proposed criterion is sensitive to changes in both unsteady aerodynamic loads and the vibration modeshapes. The proposed methodology was applied to a typical core-compressor forced response case for which measured data were available. The Reynolds-averaged Navier-Stokes equations were used to represent the flow in a non-linear time-accurate fashion on unstructured meshes of mixed elements. The structural model was based on a standard finite element representation from which the vibration modes were extracted. The blade flexibility was included in the model by coupling the finite element model to the unsteady flow model in a time-accurate fashion. A series of numerical experiments were conducted by altering the stator wake and using the proposed indicator functions to minimize the rotor response levels. It was shown that a fourfold response reduction was possible for a certain mode with only a minor modification of the blade.

Control of Static Shape, Dynamic Oscillation, and Thermally Induced Vibration of Nozzles

2005 ◽  
Vol 128 (3) ◽  
pp. 357-363 ◽  
Author(s):  
D. W. Wang ◽  
H. S. Tzou ◽  
S. M. Arnold ◽  
H.-J. Lee
Keyword(s):  
Finite Element ◽  
Conical Shell ◽  
Shape Control ◽  
Numerical Data ◽  
Analysis Data ◽  
Mode Shapes ◽  
Thermal Excitation ◽  
Thermally Induced ◽  
Control Effectiveness ◽  
And Control

Static shape actuation and dynamic control of nozzles can improve their performance, accuracy, reliability, etc. A new curved laminated piezothermoelastic hexahedral finite element is formulated based on the layerwise constant shear angle theory and it is used for modeling and analysis of piezothermoelastic conical shell structures subjected to control voltages for static shape actuation and dynamically and thermally induced vibration controls. Free vibration characteristics of an elastic truncated conical shell nozzle with fixed-free boundary conditions are studied using the new finite element. Both frequencies and mode shapes are accurately computed and compared favorably with available experimental and other numerical data. This study is then extended to evaluate control effectiveness of the conical shell with laminated piezoelectric layers. Static shape control is achieved by an applied electric potential. Vibration sensing and control are carried out using the negative velocity control scheme. Control of thermal excitation is also investigated. Analysis data suggest that the dynamic behavior and control characteristics of conical shells are quite complicated due to the coupled membrane and bending effects participating in the responses. To improve control effectiveness, segmentation and/or shaping of sensor and actuator layers need to be further investigated.

A Method for FE Model Updating of Coupled Vibro-Acoustic Systems Using Constrained Optimization

2013 ◽  
Author(s):  
D. V. Nehete ◽  
S. V. Modak ◽  
K. Gupta
Keyword(s):  
Finite Element ◽  
Constrained Optimization ◽  
Model Updating ◽  
Numerical Study ◽  
Element Model ◽  
Rectangular Cavity ◽  
Mode Shapes ◽  
Fe Model ◽  
Structural Dynamic ◽  
Fe Model Updating

Finite element (FE) model updating is now recognized as an effective approach to reduce modeling inaccuracies present in an FE model. FE model updating has been researched and studied well for updating FE models of purely structural dynamic systems. However there exists another class of systems known as vibro-acoustics in which acoustic response is generated in a medium due to the vibration of enclosing structure. Such systems are commonly found in aerospace, automotive and other transportation applications. Vibro-acoustic FE modeling is essential for sound acoustic design of these systems. Vibro-acoustic system, in contrast to purely structural system, has not received sufficient attention from FE model updating perspective and hence forms the topic of present paper. In the present paper, a method for finite element model updating of coupled structural acoustic model, constituted as a problem of constrained optimization, is proposed. An objective function quantifying error in the coupled natural frequencies and mode shapes is minimized to estimate the chosen uncertain parameters of the system. The effectiveness of the proposed method is validated through a numerical study on a 3D rectangular cavity attached to a flexible panel. The material property and the stiffness of joints between the panel and rectangular cavity are used as updating parameters. Robustness of the proposed method under presence of noise is investigated. It is seen that the method is not only able to obtain a close match between FE model and corresponding ‘measured’ vibro-acoustic characteristics but is also able to estimate the correction factors to the updating parameters with reasonable accuracy.

scholarly journals Research of Jiles-Atherton Dynamic Model in Giant Magnetostrictive Actuator

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Yongguang Liu ◽  
Xiaohui Gao ◽  
Chunxu Chen
Keyword(s):  
Mathematical Model ◽  
Dynamic Model ◽  
Control Strategies ◽  
Structural Parameters ◽  
Hysteresis Loops ◽  
Structural Dynamic ◽  
Magnetostrictive Actuator ◽  
Output Characteristics ◽  
And Control ◽  
Minor Hysteresis Loops

Due to the existence of multicoupled nonlinear factors in the giant magnetostrictive actuator (GMA), building precise mathematical model is highly important to study GMA’s characteristics and control strategies. Minor hysteresis loops near the bias magnetic field would be often applied because of its relatively good linearity. Load, friction, and disc spring stiffness seriously affect the output characteristics of the GMA in high frequency. Therefore, the current-displacement dynamic minor loops mathematical model coupling of electric-magnetic-machine is established according to Jiles-Atherton (J-A) dynamic model of hysteresis material, GMA structural dynamic equation, Ampere loop circuit law, and nonlinear piezomagnetic equation and demonstrates its correctness and effectiveness in the experiments. Finally, some laws are achieved between key structural parameters and output characteristics of GMA, which provides important theoretical foundation for structural design.

scholarly journals Finite Element Modelling of Laser Stitch Welding Joints for Structural Dynamic Predictions

2019 ◽  
Vol 16 (2) ◽  
pp. 6556-6567
Author(s):  
M. A. S. Aziz Shah ◽  
M. A. Yunus ◽  
M. N. Abdul Rani ◽  
M. S. Mohd Zin ◽  
W. I. I. Wan Iskandar Mirza
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Dynamic Behaviour ◽  
Welding Process ◽  
Shell Element ◽  
High Strength ◽  
Mode Shapes ◽  
Finite Element Models ◽  
Structural Dynamic ◽  
Welded Structure

Laser stitch welding is a joining technique that has been increasingly popular in automotive industries, such as in the manufacturing and assembling of the car’s body-in-white (BiW) due to its advantages over the resistance spot weld, such as low heat application and high strength weld. The dynamic behaviour of a laser stitch welded structure is relatively difficult to predict accurately due to local parameters being induced during the laser welding process, such as heat affected zone (HAZ) and residual stress in the welded structure. This paper presents the idea of modelling the laser stitch weld by investigating different types of element connectors that can be used to represent laser stitch weld, such as rigid body element (RBE2), shell element (CQUAD4), bar element (CBAR) and area contact model (ACM2) format of element connectors. The accuracy of finite element models of laser stitch welded joints is compared in terms of natural frequencies and mode shapes with the experiment counterparts. The dynamic behaviour of the measured structure is obtained by using an impact hammer with free-free boundary conditions. It is found that the accuracy of the finite element models of the laser stitch welded structure highly depends on the involvement of residual stress and the heat affected zones that are generated from the welding process.

Improved Results in Structural Dynamic Calculations by Linking Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA)

1995 ◽  
Author(s):  
Ulrich Gabbert ◽  
Manfred Zehn ◽  
Friedrich Wahl
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Numerical Models ◽  
Mass Matrix ◽  
Computer Time ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Structural Dynamic

Abstract The paper deals with improvements of accuracy of structural dynamic calculations by using both the advantages of Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA). The basis for such improvements are reasonable mechanical and numerical models and accurate frequency response measurements (eigenfrequencies and mode shapes). The paper deals first with reasons for and estimations of errors in numerical and experimental analysis. It can be shown by theory and experiment that neither FEA nor EMA models are unique, due to inevitable incompleteness of the mode shapes and eigenfrequencies from a vibration test. Verification and updating of FE models by linking FEA with EMA are discussed in the paper and mainly focussed on FE models with a large number of degrees of freedom. Hence an update method has been introduced, which leads to an improved model in a relatively small quantity of computer time. It can be shown, that based on measured eigenfrequencies and calculated eigenvectors, an updating of FE-models for real engineering problems, by changing the mass matrix only, is a very efficient procedure with a surprisingly good quality updated model.

A multibody dynamic model for predicting operational load spectra of dual clutch transmissions

2021 ◽  
Vol 263 (2) ◽  
pp. 4132-4143
Author(s):  
Murat Inalpolat ◽  
Enes Timur Ozdemir ◽  
Bahadir Sarikaya ◽  
Hyun Ku Lee
Keyword(s):  
Steady State ◽  
Dynamic Model ◽  
Forced Vibration ◽  
Linear Time ◽  
Vibration Response ◽  
Operating Conditions ◽  
Mode Shapes ◽  
Time Step ◽  
Gear Mesh ◽  
Multibody Dynamic

In this paper, a generalized nonlinear time-varying multibody dynamic model of dual clutch transmissions (DCT) is presented. The model consists of clutches, shafts, gears and synchronizers, and can be used to model any DCT architecture. A nonlinear clutch model is used to determine the transmitted power to the transmission at any speed and clutch temperature. The clutch can be a single- or multi-plate clutch and can operate in a wet or dry-clutch configuration. A combined kinematic and powerflow simulation enables calculation of gear, shaft, bearing and clutch quasi-static loads as well as gear mesh frequencies following a duty cycle as the input. For the corresponding Linear-Time-Invariant (LTI) system model, natural frequencies and mode shapes are obtained by solving the eigenvalue problem. The modal summation technique is used to determine the steady state forced vibration response of the system. For the corresponding NTV system, Newmark's time-step marching based integration is used to determine both the steady state and transient forced vibration response of the system. The DCT model is exercised using a common transmission architecture operating at several different operating conditions. The resulting impact of changing operational conditions on gear and bearing loads as well as dynamic transmission error spectra are demonstrated.

FEM Analysis of a Diesel Engine’s Cylinder Head

2012 ◽  
Vol 490-495 ◽  
pp. 3023-3026
Author(s):  
Shao Zhong Jiang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Cylinder Head ◽  
High Speed ◽  
Structural Characteristics ◽  
Fem Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Frequency Distributions ◽  
And Control

The article aims at the cylinder head used in a high speed and higher-power diesel engine. In order to obtain the vibration characteristics and vibration frequency distributions. By means of modal analysis technology and finite element method (FEM), structural characteristics of the cylinder head using modal analysis is investigated. Firstly, a physical model of the cylinder head is built. Through the comparison of all the modal analysis results with different meshing densities, a tetrahedron ten-node element with length of 30mm is selected. Then finite element analysis of the model is taken by FEM software. The cylinder head’s modal parameters namely its natural frequency are calculated and its mode shapes are identified. The results can provide basis for the engine’s dynamic analysis and control of the diesel engine’s noise

1.5MW Wind Turbine Structural Dynamic Analysis

2012 ◽  
Vol 522 ◽  
pp. 323-326
Author(s):  
Jie Kai Gong ◽  
Wen Lei Sun ◽  
An Wu
Keyword(s):  
Wind Turbine ◽  
Dynamic Model ◽  
Mode Shapes ◽  
Systematic Design ◽  
Structural Dynamic ◽  
Wind Field Model ◽  
Structural Dynamic Model ◽  
Design And Manufacturing ◽  
Shaft Torque ◽  
Important Significance

In recent decades, the rapidly development of wind energy in China and the increasing of size and complexity of wind turbine have requested the improvement in wind turbine systematic design technology. A reasonable systematic dynamic model is an important part for systematic design of MW-class wind turbine. In structural dynamic model, the flexibility of blade and tower is represented by presumed mode shapes. In this paper, based on presumed mode shape method, the structural dynamic equations of wind turbine were constructed. Along with the wind field model, the wind turbine aeroelastic systematic dynamic model was constructed. Using the model, the deflections and load of blade, low speed shaft torque of a 1.5MW wind turbine have been calculated. Therefore, the construction of wind turbines systematic dynamic model has an important significance for the development of wind systematic design and manufacturing capacity.

Control of Static Shape, Dynamic Oscillation, and Thermally Induced Vibration of Nozzles

Aerospace ◽  
2003 ◽  
Author(s):  
D. W. Wang ◽  
H. S. Tzou ◽  
S. M. Arnold
Keyword(s):  
Finite Element ◽  
Conical Shell ◽  
Shape Control ◽  
Numerical Data ◽  
Analysis Data ◽  
Mode Shapes ◽  
Thermal Excitation ◽  
Thermally Induced ◽  
Control Effectiveness ◽  
And Control

Static shape actuation and dynamic control of nozzles can optimize their performance, accuracy, reliability, etc. A new curved laminated piezothermoelastic hexahedral finite element is formulated based on the layerwise constant shear angle theory and it is used for modeling and analysis of piezothermoelastic conical shell structures subjected to control voltages for static shape actuation, dynamic and thermally-induced vibration controls. Free vibration characteristics of an elastic truncated conical shell nozzle with fixed-free boundary conditions are studied using the new finite element. Both frequencies and mode shapes are accurately computed and compared favorably with the experimental and other numerical data. This study is then extended to evaluate control effectiveness of the conical shell with laminated piezoelectric layers. Static shape control is achieved by an applied electric potential. Vibration sensing and control are carried out using the negative velocity control scheme. Control of thermal excitation is also investigated. Analysis data suggests that the dynamic behavior and control characteristics of conical shells are quite complicated due to the coupled membrane and bending effects participating in the responses. To improve control effectiveness, segmentation and/or shaping of sensor and actuator layers need to be further investigated.

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