NUMERICAL INVESTIGATION TO IDENTIFY MODAL PARAMETERS
CONSIDERING FIBER ORIENTATION OF FLEXIBLE COMPOSITE
WING
Eduardo Araujo
2014
der L. Oliveira*1, Roberto G. A. da Silva2, Adolfo G. Marto2, Eduardo F. R. de Araujo3
NUMERICAL INVESTIGATION TO IDENTIFY MODAL PARAMETERS
CONSIDERING FIBER ORIENTATION OF FLEXIBLE COMPOSITE WING
MODELS
1Instituto Tecnolgico de Aeronutica
2Instituto de Aeronutica e Espao
[email protected], [email protected]
3Engineering Scientific Simulation Software
INTRODUCTION
Introduction
Purposes of this work:
to understand the influence of different fiber orientations of thin composite
wing models on modal parameters.
to observe the influence of a piezoelectric (PZT) actuator in modal parameters
This work is related to intelligent structures, i.e., to have the ability to control
some displacements and stresses through some information collecting sensor
like PVDF films, and to actuate through PZT .
Introduction
Numerical Modal Analyses (NMA) is performed with ANSYS Workbench
5 simplified wing Models with different unidirectional carbon fiber orientation were modeled.
The model is a coupled model: Composite Structure modeled using ACP and later parametrized
1 PZT (Lead Zirconate Titanate) actuator
1 PVDF (Polyvinylidene Fluoride) sensor.
Introduction
Smart material influence observed
- structural damping
- local stiffness
- mass
Fiber orientation influence
- natural frequencies
- Vibration modes / twist vibration modes / flutter speed
Introduction
This work was verified through
experiments. See references [6] and [11].
Numerical Model Description
Numerical model
Numerical model
Figure 1. Composite wing model, dimensions and nominal orientation [6]
Numerical Model : Properties
Figure2: Numerical model and material properties
Initial Numerical Model (INM)
Classical Laminate Teory (CLT) INM
The INM creates using ANSYS uses the complete stress-strain relation.
Shear Moduli
Initial Numerical Model (INM)
Classical Laminate Theory (CLT) [6]
stress-strain relation in principal
material coordinates for a lamina
of an orthotropic material under
plane stress. Reduced stiffness
Engineering shear strain
Normal strain
Normal stress
Transverse shear stress
Check Step for Geometry and Meshing
Composite Modeling, Modal Analysis and
Harmonic Response with Electric Excitation
Numerical Model
Relevant Data
Composite wing model: SHELL181
Piezoelectric elements: SOLID226
Number of elements: 14300
Number of nodes: 20300
Mechanical loading values (displacements) due the difference of potential (Volts) imposed via
APDL.
Numerical Model
Coupling Matrix: T - stress D electric displacement S - strain E electric field
Permittivity
Piezoelectric constants
Stiffness matrix
Numerical Model
Difference of electric potential is converted in displacement and applied as harmonic effort.
APDL commands
cmsel,s,Ground_lower_surface_Piezo,node
d,all,volt,0
cmsel,s,Load_upper_surface_piezo,node
d,all,volt,17
allsel
Numerical Model Description
Results: Numerical model
Results - Numerical Model
Mode Shapes (Fiber Direction 0 degrees) are presented as reference
1st Mode Shape 2nd Mode Shape
3rd Mode Shape
Results NM and EM comparison
1st NM 1st EM 2nd EM 2nd NM
NM Numerical modes by Ansys EM - Experimental modes by [3]
Fiber direction 0 degrees
Results - Numerical Model
Model is parametric
Fiber direction may be a variable (Input)
Frequency Response Data may be Output for each variable
Results - Numerical Model
0,30,45,60 and 90 degrees were considered
Results for fiber direction 45 degrees are presented here
Results Experimental x Numerical Modal Analysis (45 degrees)
1st Mode Shape 2nd Mode Shape 3rd Mode Shape
Numerical
Experimental
Results - Numerical Model
Bode diagram: Amplitude X-Direction and Phase
Fiber direction 45 degrees
Results - Numerical Model
Bode diagram: Amplitude Y-Direction and Phase
Fiber direction 45 degrees
Results - Numerical Model
Bode diagram: Amplitude Z-Direction and Phase
Fiber direction 45 degrees
Results Experimental Model
Measurements were done using Vibrometer Laser and PVDF
One of objectives of this work was to validate the usage fo PVDF device as sensor
Image below shows the measurements obtained from the laser vibrometer and from the PVDF for the same experiment (same conditions) [11]
Note: Mobility (V/F)
Results - Numerical Model
Bode diagram: Velocity Z-Direction and Phase
Fiber direction 45 degrees
Conclusions
Coupled piezoeletric model available through Ansys r15
One may perform Modal and Harmonic Analysis
Results shows a good agreement between mode shape calculated numerically and the experimental ones
Results show that variations in the orientation have a significant influence on the stiffness, mode shapes and characteristic frequencies
Next work step is to compare these numerical results with experimental by EMA of the same flexible composite wing models, and to perform aeroelastic analyses using wind tunnel testing.
References
[1] C. E. de Souza, A. G. Marto, R. G. A. Silva, L. A. Inojosa, E. L. Oliveira, Characterization of Flexible Composite Wings Through Experimental and Operational Modal Analyses, DINAME 2013: Proceedings of the XV International Symposium on Dynamic Problems of
Mechanics, M.A. Savi (Editor) (2013).
[2] . L. Oliveira, A. G. Marto, R. G. A. da Silva, Thin Aeroelastic Wing Finite Element Model Updating with Experimental modal Analysis Results, Proceedings of COBEM 2011, 21st International Congress of Mechanical Engineering, October 24-28, 2011, Natal, RN,
Brazil.
[3] C. E. Prazzo, Anlise Modal de uma Estrutura do Tipo Viga Usando Materiais Piezeltricos (PVDF) Como Sensores (in portuguese), Dissertao de mestrado em Engenharia Mecnica - UNESP. Faculdade de Engenharia de Ilha Solteira., 2011.
[4] C. dos S. Guimares, Shape Control of Structures Using Piezoelectric Components, 2010, 109f. Trabalho de Concluso de Curso. (Graduao) ITA, So Jos dos Campos.
[5] ANSYS Mechanical APDL Technology Demonstration Guide, release 14.5 SAS IP, Inc Canonsburg ,nov 2011
[6] C. E. de Souza, Nonlinear Aeroelasticity of Composite Flat Plates, 2012, 170f. Thesis of Doctor in Science Technological Institute of Aeronautics, So Jos dos Campos.
References
[7] C. dos S. Guimares, F. L. de S. Bussamra, V. P. Bundiger, J. A. Hernandes, Structural Shape Control Using Macro Fiber Composite Piezoelectric Sensors and Actuators , Mecnica Computacional Vol XXIX, pgs. 8263-8279 (artculo completo) Eduardo Dvorkin, Marcela Goldschmit, Mario Storti (Eds.) Buenos Aires, Argentina, 15-18 Noviembre 2010.
[8] R. M. Jones, Mechanics of Composite Materials, 2nd ed. Washington: Scripta Book Co., 1999.
[9] J. Reddy, Mechanics of Laminated Composite Plates: theory and analysis, Boca Raton: CRC Press, 1997.
[10] D. J. Ewins, Modal Testing: theory and practice Letchworth: Reserch Studies Press Ltd, 1986.
[11] Oliveira, E.L. Application of Piezoeletric materials as sensor and actuator for aeroelastic investigation, Master of Science Thesis presented to Instituto Tecnologico de Aeronautica, So Jose dos Campos, Brasil, 2014
[12]Kostetzer, L. Piezoeletric Simulation with Ansys, ESSS, Florianpolis, Brasil, 2013
Acknowledgments