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Fundamental Constitutive Modeling of Magnetorheological
Fluid and its Application on Reconfigurable Systems.
Semi-active Damper and Transmission Actuator
Title Fundamental Constitutive Modeling of Magnetorheological Fluid and its Application on Reconfigurable Systems. Semi-active Damper and Transmission Actuator Authors Villarreal González, Leopoldo S.
modified by applying a magnetic field. The most important advantage of these fluids over conventional mechanical interfaces is their ability to achieve a wide range of viscosity in a fraction of millisecond. According to bibliography and patent analyses a growing tendency around MR technology is observed and its application on reconfigurable systems is feasible. The main objective of this thesis is to describe the main parameters affecting the magnetorheological fluids by the creation of a constitutive expression that can be consider in the design of
reconfigurable systems. In addition to conceptualize and to characterize two prototype systems; a semi-active damper and a transmission actuator. The thesis is divided in five chapters. First chapter refers to background analysis and aims, where the problem statement and the followed methodology are presented. Second chapter presents the state of the art, where MR technology and trends are analyzed. In the third chapter, the analysis of the MR fluid under different magnetic fields is carried out. Finally, in chapter four and five, applications related with semi-active damper and transmission actuator systems are
characterized. The results obtained in this thesis are the identification of the main parameters which affect the magnetorheological fluids. Fundamental models expressions to determine the viscosity of MR to be considered in the design of reconfigurable systems are presented. Constitutive models of two kinds of systems: a transmission actuator and a semi-active damper system. Finally, due to its ability to be adjusted and its quick response to a magnetic field change, MR technology is a feasible way in the development of reconfigurable systems. Discipline Ingeniería y Ciencias Aplicadas / Engineering & Applied
Sciences
Item type Tesis
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Dr. Jorge Armando Cortés Ramírez
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SUPERIORES D E MONTERREY
CAMPUS MONTERREY
DIVISIÓN DE INGENIERÍA Y ARQUITECTURA PROGRAMA DE GRADUADOS EN INGENIERÍA
TECNOLÓGICO
DE MONTERREY
®FUNDAMENTAL CONSTITUTIVE MODELING OF MAGNETORHEOLOGICAL FLUID AND ITS APPLICATION ON
RECONFIGURABLE SYSTEMS
- Semi-active Damper and Transmission
Actuator-T E S I S
PRESENTADA COMO REQUISITO PARCIAL PARA OBTENER EL GRADO ACADÉMICO DE:
MAESTRO EN CIENCIAS
ESPECIALIDAD EN SISTEMAS DE MANUFACTURA
POR:
LEOPOLDO SALVADOR VILLARREAL GONZÁLEZ
S
UPERIORES
D
E
M
ONTERREY
C
AMPUS
M
ONTERREY
D
IVISIÓN DEI
NGENIERÍA YA
RQUITECTURAP
ROGRAMA DEG
RADUADOS ENI
NGENIERÍALos miembros del comité de tesis recomendamos que la presente tesis del
Ing. Leopoldo Salvador Villarreal González sea aceptada como requisito
parcial para obtener el grado académico de Maestro en Ciencias
Especialidad en:
SISTEMAS DE MANUFACTURA
C
OMITÉ DET
ESIS______________________________
____________________________
Dr. Jorge Armando Cortés Ramírez. Dr. Jaime Bonilla Ríos
A
SESORC
O-A
SESOR__________________________
Dr. Ciro A. Rodríguez González
S
INODAL.
APROBADO.
__________________________________
Dr. Federico Viramontes Brown.
D
EDICATED TOA
DIOS
A
MIESPOSA,
GRACIAS POR TU APOYO,
AMOR Y CONFIANZA.
N
ADIA GRACIAS POR SER PARTE DE MI VIDA Y COMPARTIRCONMIGO ESTE SUEÑO
.
A
MIPAPÁ,
GRACIAS POR TU APOYO Y POR SER MI GRAN EJEMPLODE DEDICACIÓN
,
ESFUERZO Y HONESTIDAD.
A
MIMAMÁ,
GRACIAS POR TU APOYO INCONDICIONAL,
POR SERMI AMIGA Y POR CREER SIEMPRE EN MI
.
G
RACIASP
APÁS POR LOS VALORES QUE ME INCULCARON,
POR LAEDUCACIÓN QUE ME BRINDARON
,
POR SUS ORACIONES Y PORQUEGRACIAS A DIOS Y A USTEDES HE ALCANZADO ESTA META
.
A
MISIS,
POR TODO SU APOYO Y CARIÑO.
P
OR SER EJEMPLO YMOTIVACIÓN EN LA LUCHA POR ALCANZAR NUESTROS SUEÑOS
.
A
MIPAPA
TOÑO,
PORQUE OFRECÍ MI TRABAJO POR TÍ Y PORQUEA
CKNOWLEDGEMENTSA Dios por permitirme concluir esta etapa, por ser mi motor, mi gran amigo y mi
guía.
Agradezco a mi asesor, el Dr. Jorge Cortés Ramírez, por su apoyo constante,
tiempo y dedicación durante la realización de mi tesis
Agradezco a mi co-asesor, el Dr. Jaime Bonilla por su apoyo y asesorias.
Agradezco a mi Sinodal el Dr. Ciro Rodríguez por sus valiosos comentarios y
sugerencias.
Al CONACYT-ITESM por la beca de excelencia otorgada para la realización de
mi maestría
Agradezco al Dr. Manuel Martínez Martínez (Campus Saltillo), al Dr. Enrique
Jiménez (CIQA), a la Ing. Lorena Cruz y al Ing. Luis Carlos Ríos (Campus Monterrey)
por las facilidades que nos brindaron en el uso sus laboratorios.
Agradezco a al Centro de Innovación y Diseño del Producto a través de la Cátedra
de Mecatrónica por su apoyo económico para la realización de esté trabajo
A mis amigos de la maestría: Gilberto Reynoso, Iván Pulido, Roberto Rosas,
Ricardo Camacho, Andrés Valverde, Rogelio De la Garza, Anabelle Lopéz, José Luis
Mendoza, Analía García, Natalia López, Juan Manuel Wong, Gerardo Trejo, Benito
Flores, Leopoldo Morales, Alejandra de la Vega, Leonardo Cortés, Keren Baltazar,
Aáron Treviño y Javier Jauregui.
A todos los alumnos de PADS por su valiosa participación en esta investigación:
Daniel Sánchez, Francia Galindo, Horacio Elizondo, José Juan Garza, Oscar González,
Jesús Nava, David Garza, Aldo Leal, Alejandro Reynoso, Alejandro Ontiveros, Carlos
Zuazua, César Zayas y Raúl Garza.
A mis profesores, por todas sus enseñanzas: Dr. Jorge Cortés, Dr. Noel León, Dr.
José Luis González, Dr. Alberto Hernández, Dr. Jaime Bonilla, Dra. Gabriela Pedroza y
F
OR THER
EADERThe thesis presented has a different format with respect to the traditional ones, for
that reason, before you start to read this thesis it is important to let you know its structure
and organization characteristics, so that, you will better understand and comprehend it.
First, this thesis has 6 chapters. Two of them correspond to the background,
chapter one, and the conclusions, chapter six. Such chapters follow the traditional thesis
presentation format.
The middle chapters are written based on a format used for articles, that it means,
that each chapter has its own introduction, purpose, methodology, analysis, results and
conclusions. For that reason, as a guide to avoid possible confusions, it has been added a
header with the name of the corresponding chapter.
In the other hand, the thesis is written in such form, that when you read any
chapter you will understand it, even if you have not read the thesis in order. For that
reason, the reader could found “repetitive” information. The chapters are presented in an
independent way, however, all are related between them and have a defined sequence
A
BSTRACTMagnetorheological (MR) fluids belong to the general class of smart material
whose rheological properties can be modified by applying a magnetic field. The most
important advantage of these fluids over conventional mechanical interfaces is their
ability to achieve a wide range of viscosity in a fraction of millisecond. According to
bibliography and patent analyses a growing tendency around MR technology is observed
and its application on reconfigurable systems is feasible.
The main objective of this thesis is to describe the main parameters affecting the
magnetorheological fluids by the creation of a constitutive expression that can be
consider in the design of reconfigurable systems. In addition to conceptualize and to
characterize two prototype systems; a semi-active damper and a transmission actuator.
The thesis is divided in five chapters. First chapter refers to background analysis
and aims, where the problem statement and the followed methodology are presented.
Second chapter presents the state of the art, where MR technology and trends are
analyzed. In the third chapter, the analysis of the MR fluid under different magnetic fields
is carried out. Finally, in chapter four and five, applications related with semi-active
damper and transmission actuator systems are characterized.
The results obtained in this thesis are the identification of the main parameters
which affect the magnetorheological fluids. Fundamental models expressions to
determine the viscosity of MR to be considered in the design of reconfigurable systems
are presented. Constitutive models of two kinds of systems: a transmission actuator and a
semi-active damper system. Finally, due to its ability to be adjusted and its quick
response to a magnetic field change, MR technology is a feasible way in the development
L
IST OFF
IGURESFigure 1.1 Manufacturing systems trends……….. 3
Figure 1.2 Aspects of reconfiguration……… 4
Figure 2.1 MR fluid capabilities demonstration by Rabinow……… 9
Figure 2.2 MR Fluid taxonomy from the point of view: area-device-application……. 13
Figure 3.1 MR fluid………... 21
Figure 3.2 Prototype clutch design. (Concentric Cylinders)………. 22
Figure 3.3 Experimental arrangement. (A) Coil, (B) Input Shaft (C) Output Shaft….. 23
Figure 3.4 Iron powder particle size analysis……… 24
Figure 3.5 Iron Powder Micrographs………. 25
Figure 3.6 Shear Stress-Shear rate relationship of commercial products……….. 26
Figure 3.7 Viscosity-Shear rate relationship of commercial products……….. 26
Figure 3.8 Viscosity/Shear Stress-Shear rate peanut butter relationship……….. 27
Figure 3.9 Brookfield rheometer system………... 27
Figure 3.10 Paar Physica rheometer system……….. 28
Figure 3.11 Prototype clutch experiments with commercial products……….. 29
Figure 3.12 Prototype clutch experiments with MR fluid………. 29
Figure 3.13 MR fluid viscosity behavior analysis………. 30
Figure 4.1 (a) Magnetorheological fluid and (b) prototype brake damper……… 35
Figure 4.2 Experimental arrangement: (A) Coil, (B) Input Shaft (C) Output Shaft….. 36
Figure 4.3 MR fluid behavior inside concentric cylinders without magnetic field applied…... 37 Figure 4.4. MR fluid behavior inside concentric cylinders with magnetic field applied………. 38 Figure 4.5 Experimental relationship: Current-Output Speed-Input Speed…………... 39
Figure 4.6 Current and speed percentages. General Curve……… 41
Figure 4.7 Model and experimental data comparative analysis………. 42
Figure 4.8 Actuator model analysis………... 43
Figure 5.1 (a) Magnetorheological fluid and (b) prototype damper……….. 47
Figure 5.2 Experimental arrangement. (a) Coil and (b) Fastener……….. 48
Figure 5.3 MR fluid behavior inside damper without a magnetic field applied……… 49
Figure 5.4 MR fluid behavior inside the damper with a magnetic field applied……… 49
Figure 5.5 Mathematical identification of relationship force-displacement when a magnetic field of 890 Gauss is applied.………... 50
Figure 5.6 (a) Constant a, and (b) constant b analysis……….. 51
Figure 5.7 Equivalent Damping Coefficient analysis……… 52
L
IST OFT
ABLES Table 2.1 MR fluids Area-Application relationship……….. 11Table 2.2 MR fluid patent classification by application……… 11
Table 2.3 MR fluid patent classification by year……….. 12
Table 4.1 Constant values of equations found.…………... 40
I
NDEXDEDICATED TO... I
ACKNOWLEDGEMENTS...II
FOR THE READER... III
ABSTRACT... IV
LIST OF FIGURES... VIII
LIST OF TABLES... IX
SYMBOLOGY... X
Chapter 1 BACKGROUND AND AIM.……….... 1
1.1. BACKGROUND………. 1
1.2. JUSTIFICATION………... 2
1.3. Aim of the present work……….……… 4
1.4. Methodology……….. 5
1.5. References……….. 7
Chapter 2 STATE OF THE ART………. 8
2.1. Background……… 8
2.2. Objective……… 10
2.3. Methodology……….. 10
2.4. Results……… 10
2.4.1. Bibliography search………... 10
2.4.2. Patent Analysis……….. 11
2.4.3. Taxonomy……….. 12
2.5. Conclusions……… 14
2.6. References……….. 16
Chapter 3 Magnetorheological Fluid Characterization………. 20
3.1. Introduction……… 20
3.2. Purpose………... 20
3.3. Methodology……….. 20
3.4.1. MR Fluid General Description……….. 21
3.4.2. Experimental Arrangement Description……… 22
3.5. Results……… 23
3.5.1. Particle Size distribution and shape analysis………. 23
3.5.2. Rheology analysis of commercial products……... 24
3.5.3. Rheology analysis of magnetorheological fluid………. 28
3.6. Conclusions……… 32
3.7. References……….. 33
Chapter 4 CHARACTERIZATION,MODELING AND SIMULATION OF MAGNETORHEOLOGICAL CLUTCH SYSTEM TO DEVELOP A RECONFIGURABLE DEVICE………... 34
4.1. Introduction……… 34
4.2. Purpose………... 34
4.3. Methodology……….. 34
4.4. System Description……… 35
4.5. Results……… 38
4.5.1. Characterization of MR Brake………... 38
4.5.2. Mathematical Identification………... 39
4.5.3. Simulation of MR Brake System………... 43
4.6. Conclusions……… 44
4.7. References………. 45
Chapter 5 Characterization, Modeling and Simulation of Magnetorheological Damper Behavior under Triangular Excitation………. 46
5.1. Introduction……… 46
5.2. Purpose………... 46
5.3. Methodology……….. 46
5.4. System Description……… 47
5.5. Results……… 49
5.5.1. Characterization of MR Damper……… 49
5.6. Conclusions………. 53
5.7. References……….. 54
Chapter 6 Conclusions………... 55
Future Work………. 56
Journals, Conferences and Awards……… 57
Appendix A. MR Clutch Drawings... 58
Appendix B. Magnetic Field Analysis……… 63
Figure 5.1 (a) Magnetorheological fluid and (b) prototype damper……….. 47
Figure 5.2 Experimental arrangement. (a) Coil and (b) Fastener……….. 48
Figure 5.3 MR fluid behavior inside damper without a magnetic field applied……… 49
Figure 5.4 MR fluid behavior inside the damper with a magnetic field applied……… 49
Figure 5.5 Mathematical identification of relationship force-displacement when a magnetic field of 890 Gauss is applied.………... 50
Figure 5.6 (a) Constant a, and (b) constant b analysis……….. 51
Figure 5.7 Equivalent Damping Coefficient analysis……… 52
L
IST OFT
ABLES Table 2.1 MR fluids Area-Application relationship……….. 11Table 2.2 MR fluid patent classification by application……… 11
Table 2.3 MR fluid patent classification by year……….. 12
Table 4.1 Constant values of equations found.…………... 40
S
YMBOLOGYER Electrorheological
RMS Reconfigurable Manufacturing Systems
A Ampere
DC Direct Current
a Power equation constant
b Power equation exponential constant
c Equivalent damping coefficient
cP= mPas Centipoise
DC Direct Current
EDC MR equivalent damping coefficient
δ Damper displacement or deformation
F Force exerted by the damper
ƒ Force required to overcome damper resistance
hr hour
i=I current through the coil
km Kilometer
MR Magnetorheological
MF Magnetic field
µm micrometer
m meter
mm millimeters
min minute
s seconds
N Newton
x Piston rod velocity
τy Yield Stress
HP Horse power
d, f and g Clutch constant sigmoidal equations
β
Clutch general curve constant valueG Gauss
GC Characteristic Magnetic Field
RPM Revolution per minute
η
Viscosity of the suspensions
η
Viscosity of the carrier liquidφ
Volume fraction of the dispersed phaseE
k
Coefficient which refers to particles interactions
SR Speed Rate
Ω Angular velocity
1.
B
ACKGROUND ANDA
IMS1.1.BACKGROUND
The changes in manufacturing environment is characterized by aggressive
competition on a global scale and rapid changes in process technology, it requires
creation of production systems easily upgradable by themselves and into which new
technologies and new functions can be readily integrated [1.1]. In USA; industry,
government and other institutions have identified, materials and manufacturing trends for
2020 [1.2 - 1.3].
The Materials Technology Vision committee, in the publication of “Technology
Vision 2020-The U.S. Chemical Industry” launched in 1996, has identified a number of
broad goals, which are enclosed in five main areas [1.2]:
• New materials
• Materials characterization
• Materials Modeling and prediction
• Additives
• Recycling
An important point in this vision is the development of “smart” materials. Such
materials have properties to self-repair, actuate and transduce. Polymers, metals, ceramics
and fluids with these special characteristics belong to this class of materials and are
already used in a great diversity of applications [1.2].
In the other hand, The Visionary Manufacturing Challenges, published in 1998 by
The US National Academy of Sciences, presented six Grand Challenges [1.3]:
• Integration of Human and Technical
Resources
• Concurrent Manufacturing
• Innovative Processes
• Conversion of Information to
Knowledge
• Environmental Compatibility
To reach these challenges, innovative processes to design and manufacture new
materials and components along with adaptable, integrated equipment, processes, and
systems that can be readily reconfigured for a wide range of customer requirements for
products, features, and services are needed [1.3].
1.2.JUSTIFICATION
The field of smart materials and structures is emerging rapidly with technological
innovations appearing in engineering materials, sensors, actuators and image processing
[1.4].
Magnetorheological fluids belong to this general class of smart materials whose
rheological properties can be modified by applying a magnetic field, reconfigurable
material. The most important advantage of these fluids over conventional mechanical
interfaces is their ability to achieve a wide range of viscosity (several orders of
magnitude) in a fraction of millisecond. This provides an efficient way to control
vibrations, and applications dealing with actuation, damping, robotics and mechatronics
have been developed [1.5].
In the other hand, next manufacturing system generation requires of reconfigurable
systems which go beyond the objective of mass, lean and flexible manufacturing systems.
Because of the manufacturing trends towards a customer focused production, figure 1.1.
A reconfigurable manufacturing system is designed in order to rapid adjustment of
production capacity and functionality, in response to new circumstances, by
rearrangement or change of its components [1.1].
As can be seen in figure 1.2, there are many aspects of reconfiguration, such as,
configuration of the product system, reconfiguration of the factory communication
software, configuration of new machine controllers, building blocks and configuration of
and implementation of key interrelated technologies to achieve the goals of
reconfigurable manufacturing systems are needed.
[image:21.612.91.523.154.414.2]
Figure 1.1 Manufacturing systems trends.
Of relevant importance are the control, monitoring and sensing of reconfigurable
manufacturing systems. By noting that the system configuration changes, the parameters
of the production machines and some other physical parameters will change accordingly.
The controller and process monitoring systems should have the ability to reconfigure and
adapt themselves to these new conditions [1.1].
Finally, several factors in MR fluids, such as the carrier oil, the magnetic field, the
particles size and morphology among others, are important to predict and to control its
behavior in practical applications. Constitutive rheology equations and methodologies are
necessary to optimize the performance of MR fluids for particular applications such as
Figure 1.2 Aspects of reconfiguration. (Adapted from Mehrabi, 2000)
1.3.AIM OF THE PRESENT WORK
GENERAL AIM:
To describe the main parameters affecting the magnetorheological fluids by the creation
of a constitutive expression that can be consider in the design of reconfigurable systems.
In addition to conceptualize and to characterize two prototypes systems: a semi-active
damper and a transmission actuator.
SPECIFIC AIMS:
• To analyze the state of the art and to establish its feasibility to develop
Reconfigurable Manufacturing Systems.
• To characterize the magnetorheological fluid’s rheology through and analysis
of its behavior according to several applied magnetic fields.
• To develop, to characterize, to model and to simulate a reconfigurable
magnetorheological actuator system.
• To develop, to characterize and to model a reconfigurable magnetorheological
damper system.
System
Software
Control
Machine
Process
1.4.METHODOLOGY
Background and Aims: This is the introductory part of the research, which presents the
source and definition of the problem along with the planning of the work.
Activities:
• Background search
• Smart materials and Reconfigurable manufacturing systems introdcution.
State of the art: The main purpose of this chapter is to present all the work made around
MR technology since its discovery in 1942. Evolution, investigations, innovations,
commercial applications and market trends are some of the aspects analyzed.
The activities performed to accomplish this chapter are:
• Bibliographic Search
• Patent Search
• Analysis of commercial applications and market trends
Magnetorheological Fluid Characterization: The main purpose of this chapter is to
characterize the MR fluid analyzing the carrier fluid properties, additives, particles size
and shape distribution along with the viscosity behavior at different magnetic fields
strengths.
Activities:
• Make a morphological analysis of particles
• Make a particle size analysis
Characterization, Modeling and Simulation of Magnetorheological Brake/Clutch System to Develop a Reconfigurable Device: The main purpose of this chapter is to
analyze and identify a mathematical model which describes the MR fluid behavior inside
a brake/clutch under different magnetic field intensities.
Activities:
• Construction of the experimental system
• Experimental tests under different magnetic fields
• Establish a mathematical model in function of the electrical current
Characterization, Modeling and Simulation of Magnetorheological Damper Behavior under Triangular Excitation: The purpose of this chapter is to analyze and
identify a mathematical model which describes the MR fluid behavior inside a damper
under different magnetic field intensities. Also, computational simulations are developed
to analyze a suspension system at different virtual road conditions.
Activities:
• Construction of the experimental system
• Experimental tests under different magnetic fields
• Establish a mathematical model in function of the electrical current
• Simulate a suspension system to analyze it under several road conditions.
Results and Conclusions: Finally, the conclusions of the MR fluid research are
1.5.REFERENCES
1.1 Mehrabi, M.G., et al., “Reconfigurable Manufacturing Systems: Key to Future
Manufacturing”, Journal of Intelligent Manufacturing, Vol. 11, pp. 403-419,
2000.
1.2 http://www.chemicalvision2020.org/techroadmaps.html. Vision 2020 Chemical
Industry of The Future, “Technology Roadmap for Materials”
1.3 http://www.nap.edu/readingroom/books/visionary/. Visionary Manufacturing
Challenges For 2020, “Grand Challenges for Manufacturing”
1.4 VTT Industrial System, “Smart materials and structures”, VTT Research
Program 2000-2002 Seminar, pp. 6-15, 2002.
1.5 Bossis, G., et al, “Magnetorheological fluids”, Journal of Magnetism and
Magnetic Materials, vol. 252, pp. 224-228, 2002.
1.6 Macosko, Christopher, “Rheology. Principles, measurements and
applications”. Wiley-VCH: New York, 1994.
1.7 E. Yu. Taran, et al, “Features of magnetorheology of suspension with the
Cowin polar carrier fluid”, Journal of Magnetism and Magnetic Materials, 252,
2.
S
TATE OF THE ART2.1. BACKGROUND
Magnetorheological (MR) and Electrorheological (ER) fluids are intelligent fluids,
having the inherent ability to generate passive resistance forces due to its drastic increase
of shear stress in strong magnetic or electric fields. The rheology of this fluid is very
attractive since it can be monitored by the application of a magnetic or electric field [2.1].
The most important advantage of these fluids over conventional mechanical interfaces is
their ability to achieve a wide range of viscosity (several orders or magnitude) in a
fraction of millisecond.
MR fluids are mainly dispersions of particles made of a soft magnetic material in a
carrier oil. A commonly used MR fluid is made of particles of carbonyl iron in silicone
oil. Since Rabinow and Winslow’s discoveries in 1940s, magneto- and electrorheology
has emerged as a multidisciplinary field [2.2].
A typical MR fluid used by Rabinow consisted of 9 parts by weight of carbonyl
iron to one part of silicon oil, petroleum oil or kerosene. To this suspension he would
optionally add grease or other thixotropic additive to improve settling stability. An early
picture of a demonstration of the material’s strength capabilities showed an MR fluid
device supporting a 117-pound woman suspended on a swing [2.3].
A typical ER fluid used by Winslow was composed of a finely divided solid such as
starch, limestone or its derivatives, gypsum, flour, gelatin or carbon, dispersed in a
non-conducting liquid, for example lightweight transformer oil, transformer insulating fluids,
olive oil or mineral oil. The ER fluid manifests an increase in flow resistance as long as
an electrical potential difference is applied thereto [2.4].
However, Winslow also developed a basic MR formulation which was likely to
consisted of 10 parts by weight of carbonyl iron suspended in mineral oil. To this
suspension Winslow add ferrous naphthenate or ferrous oleate as a dispersant and a metal
[image:27.612.225.387.173.360.2]soap such as lithium stearate or sodium stearate as a thixotropic additive [2.3].
Figure 2.1 MR fluid capabilities demonstration by Rabinow [2.3].
Initially ER fluids received the most attention, but were found to be not as well
suited to most applications as the MR fluids.
First published information on ER fluid-based appeared in the early 1960s on force
actuators using ER valves in a bridge arrangement. However, the first useful application
of the ER fluid in vibration control was introduced by Bullough and Foxon when both
Coulomb and viscous damping was achieved by means of an ER valve-operated vibration
damper [2.5]. The relatively low strength, temperature, contaminant sensitivity and need
for high-voltage of most ER fluids has impeded their widespread commercialization
[2.3].
For decades, until the technical infrastructure grew up around it, MR fluid did not
In the last past ten years, specially in the field of mechatronics, MR fluid is actively
being researched, and numerous research activities on this fluid have been performed in
various engineering applications [2.1].
2.2. OBJECTIVE
Since 1990, magnetorheological fluid applications dealing with actuation,
damping, and robotics have been patented and are growing too fast on the market. This
chapter has the purpose of make a complete state of the art analysis around the MR
technology to determine possible research trends for Reconfigurable Machine Systems.
2.3. METHODOLOGY
To reach the objective previously defined, first a bibliography revision around
magnetorheological fluids is done to establish the state of the art along with a
classification of the technology by application and area. Secondly, a patent analysis is
done by application, year and number of patents. Posterior, a taxonomy is established
from the point of view device-application-area. Finally, a conclusion about MR
technology and its application in reconfigurable system is presented.
2.4. RESULTS
2.4.1. BIBLIOGRAPHY SEARCH
Once the bibliography search of research papers involving MR fluids technology
was performed, a classification of all the information was done and presented in Table
2.1.
As can be seen from Table 2.1, most of the research paper can be classified in
Table 2.1 MR fluids Area-Device relationship
Area
Device Manufacture
Automotive and
Machines Medicine Civil Engineering Optics Mechatronics
Adaptive
structure [2.18]
Damper
[2.6], [2.8], [2.9], [2.10], [2.11], [2.12], [2.17], [2.19], [2.21],
[2.24]
[2.7]
[2.13], [2.23],[2.25],
[2.26]
Polisher [2.27] [2.14],
[2.27]
Actuator [2.1] [2.16],
[2.20] [2.15], [2.22]
Shock Absorber [2.5]
2.4.2. PATENT ANALYSIS
From the MR fluids patent analysis, two classifications were done. The first
classification, presented on Table 2.2, refers to the number of patents related to certain
application, whereas, Table 2.3 presents an analysis of the number of registered patents
by year.
Table 2.2 MR fluid patent classification by application
Damper 78 Brakes 6 Clutch 19
Coupling Device 4
MR Fluid Materials 36
Polishing 15
Gripping/ Holder 5
Hydraulic Mount 3
Mitigate Chatter Vibration 2
Torque Transfer 10
Table 2.3 MR fluid patent classification by year
Year No. Patents
1994 3
1995 5
1996 9
1997 10
1998 18
1999 27
2000 20
2001 34
2002 41
2003 51
2004(Aug) 20
Total 238
Two important aspects can be obtained from the patent analysis. Firstly, most of
the patents developed are related with MR dampers also. Finally, it is possible to
appreciate an increase in the number of patents by year, as we can see from Table 2.3.
2.4.3. TAXONOMY
Figure 2.2 shows the MR fluids taxonomy developed with the information gotten
from the bibliography search and patent analysis. This taxonomy presents a relationship
between the area and its application.
Nowadays, most of the applications have been developed by the use of MR fluids
in dampers, not only in automotive applications but also in medical and civil engineering
areas. Nevertheless, until today, several mathematical models have been studied and
developed to describe the behavior of the MR fluid in a variety of devices, as can be seen
from the number of research papers related.
In the other hand, it is possible to appreciate a diversification along with a
growth in the areas and devices where MR fluids are applied. This trend is of great
interest because it is expected an increment in the number of patents and applications in
Figure 2.2 MR Fluid taxonomy from the point of view: area-device-application. MR FLUID Automotive Medical Manufacture Suspension Seats Civil Engineering Optical Damper Actuator Damper Actuator Clutch Brakes Damper Shock Absorber Adaptive Structure Damper Structures Buildings Bridges
Blast resistant and structural
Structures
Above Knee Prosthesis
Haptic Sensor-Actuator
Polisher
Actuator
Chatter Mitigation
Actually, on the market it is already possible to find MR fluids applications such
as car’s suspension (Cadillac’s Seville models), structures (Japan’s National Museum of
Emerging Science and Innovation and the Dong Ting Lake Bridge in China's Hunan
province) and prototype artificial knees, for example.
However, other applications are been researching, such as: clutches, haptic
devices or air-conditioning compressors [2.29]. For that reason, it is important to
continue developing methods to characterize and to understand MR fluids behavior, so
that new systems could be created and controlled. Specially, in manufacture and
mechatronics it can be seen that applications related with chatter mitigation, actuators and
miniaturized parts have been developed.
Finally, the use and development of new materials is an important part for the
accomplishment of the Materials Technology Vision and The Visionary Manufacturing
Challenges for 2020. This trend will cause that smart materials will have a predominant
participation in technology improvements and accomplishment of future challenges
[2.30, 2.31].
2.5. CONCLUSIONS
MR fluid is a recently research area that has grown up along with technical
infrastructure. Most of its actual applications are related with damper devices, even
though, a diversification is being observed and also a predominant participation in
technology improvement is expected.
The bibliography revision along with the patent analysis let establish a basis about
what kind of applications have been developed and also the growing tendency around the
MR technology development.
The taxonomy presented shows that MR fluid applications have started to be an
Finally, it is expected that smart materials, particularly MR fluids, will have a
preponderant participation in the development of Reconfigurable Manufacturing Systems
2.6. REFERENCES
2.1 Nakamura, Taro, et al, “Variable viscous control of a Homogeneous ER fluid
device considering its dynamic characteristics”, Mechatronics, vol. 14, pp.
55-68, 2004
2.2 Bossis, G., et al, “Magnetorheological fluids”, Journal of Magnetism and
Magnetic Materials, vol. 252, pp. 224-228, 2002
2.3 Lord Corporation. “Lord Rheonetic Magnetic Fluids and Systems for
vibration and Motion Control”. Web Page, 2005. January 14, 2005 last access.
http://www.mrfluid.com
2.4 Willis M. Winslow, “Method and Means for Translating Electrical Impulses
into Mechanical Force”. United States Patent Number 2,417,850, 1947.
2.5 Ali K. El Wahed, et al, “Electrorheological and magnetorheological fluids in
blast resistant design applications”, Materials and Design, Vol. 23, pp. 391-404,
2002.
2.6 Wang, En Ron, et al, “Analysis of a Semi-active MR-damper with Hysteretic
and Asymmetric Properties”, Proceedings of the American Control Conference,
IEEE, pp. 4920-4925, June 2003.
2.7 Kim, Jung Hoon and Oh, Jun-Ho, “Development of an Above Knee Prosthesis
using MR Damper and Leg Simulator”, Proceedings of the 2001 IEEE, IEEE,
pp. 3686-3691, May 2001.
2.8 Wang, Xiaojie and Gorddaninejad, Faramarz, “Dynamic Modeling of
Semi-Active ER/MR Fluid Dampers”, Proceedings of SPIE Conference on Smart
2.9 Schurter, Kyle C and Roschke, Paul N, “Fuzzy Modeling of a
Magnetorheological Damper Using ANFIS”, Proceedings of the 9th IEEE
International Conference on Fuzzy Systems, Vol. 1 , pp.122-127, May 2000
2.10 Xiao Quing Ma, et al, “Modeling Hysteretic Characteristics of MR-Fluid
Damper and Model Validation”, Proceedings of the 41st IEEE Conference on
Decision and Contrrol, Vol. 2, pp. 1675-1680, December 2002.
2.11 Dug-Young Lee, et ala, “Performance Analysis of ER/MR Impact Damper
Systems Using Herschel-Bulkley Model” Journal of Intelligent Material
Systems and Structures, Vol. 13, pp. 525-531, 2002.
2.12 Kelso, Shawn, “Experimental Characterization of Commercially Practical
Magnetorheological Fluid Damper Technology” Proceedings of SPIE
Conference of Smart Materials, Vol. 4332-34, March 2001.
2.13 Nagarajaiah, Satish et al, “Seismic Response of Sliding Bridges with MR
Dampers”, Proceedings of the American Control Conference, pp. 4437-4441,
June 2000
2.14 Tricard, Marc, et al, “SOI Wafer Polishing with Magnetorheological
Finishing(MRF)”, SOI Conference IEEE, pp.127-129, 2003
2.15 Naoyuki Takesue, et al, “Development and Experiments of Actuator Using
MR Fluid”, Proceedings of the 26th annual Conference of the IEEE, vol. 3, pp.
1838-1843, October 2000.
2.16 W. Khaled, et al, “A haptic sensor-actuator system based on ultrasound
2.17 Z. G. Ying and W. Q. Zhu, “A Stochastic Optimal Semi-Active Control
Strategy for ER/MR Dampers”, Journal of Sound and Vibration, Vol. 259,
pp.45-62, 2003.
2.18 Qing Sun, et al, “An adaptive beam model and dynamic characteristics of
magnetorheological materials”, Journal of Sound and Vibration, 261, pp.
465-481, 2003.
2.19 Ioan Bica, “Damper with magnetorheological suspension”, Journal of
Magnetism and Magnetic Materials, Vol. 241, pp. 196-200, 2002.
2.20 W. H. Li, et al, “Magnetorheological fluids based haptic device”, Sensor
Review, Vol. 24, pp. 68-74, 2004.
2.21 S.L. MacManus, et al, “Evaluation of Vibration and Shock Attenuation
Performance Of A Suspension Seat With A Semi-Active Magnetorheological Fluid Damper”, Journal of Sound and Vibration, Vol. 253, pp. 313-327, 2002
2.22 Jin-Hyeong Yoo, “Design of a High-Efficiency Magnetorheological Valve”,
Journal of Intelligent Material System and Structures, Vol. 13-10, pp. 679-685,
2002.
2.23 G. Yang, et al, “Large-scale MR fluid dampers: modeling and dynamic
performance considerations”, Engineering Structures, Vol. 24, pp.309-323,
2002.
2.24 G.Z. Yao, et al, “MR damper and its application for semi-active control of
2.25 U. Aldemir, “Optimal control of structures with semiactive-tuned mass
dampers”, Journal of Sound and Vibration, Vol. 266, pp.847-874, 2003.
2.26 W.L. Qu, et al, “Seismic response control of large-span machinery building on
top of ship lift towes using ER/MR moment controllers”, Engineering
structures, Vol. 24, pp. 517-527, 2002.
2.27 S.D. Jacobs, et al, “MRF: Computer-controlled optics manufacturing”,
American Ceramic Society Bulletin, Vol. 78, pp. 42-49, 1999.
2.28 Song, Gangbing. 2003. SMART MATERIALS Conference. “Smart materials,
lecture 5” Tec de Monterrey, Monterrey, Nuevo León, México. October 29th.
2.29 The Economist Newspaper and The Economist Group. “Going with the flow”.
Web page, 2005. January 15, 2005 last access.
http://www.economist.com/science/tq/PrinterFriendly.cfm?Story_ID=2724363.
2.30 Chemical Industry Vision 2020 Technology Partnership. “Technology
Roadmaps”. Web page, 2005. January 15, 2005 last access.
http://www.chemicalvision2020.org/techroadmaps.html.
2.31 Visionary Manufacturing Challenges For 2020. “Grand Challenges For
Manufacturing” Web page, 1998. January 10, 2005 last access.
3.
M
AGNETORHEOLOGICALF
LUIDC
HARACTERIZATION3.1. INTRODUCTION
The main interest in Magnetorheological fluids is due to their ability to show strong
and reversible variations in their rheological properties when subjected to varying
magnetic fields [3.1]. Rheological properties of controllable fluids typically depend on
the concentration and density of particles, particle size and shape distribution, properties
of the carrier fluids, additional additives, applied field, and temperature. The
interdependency of these factors is very complex, and to establish methodologies to
permit optimize the performance of these fluids for particular applications is necessary
[3.2].
3.2. PURPOSE
Constitutive rheology equations are helpful to predict and control viscoelastic fluid
flows in practical applications [3.3]. The basic problem of theoretical rheology of
suspensions is the construction of their rheological constitutive equations [3.4].
Nevertheless, experimental techniques play an important role in the modeling of such
kind of fluids. This chapter has the purpose of analyze the Magnetorheological fluid and
to demonstrate its viscosity behavior changes when it is under different magnetic fields
keeping the rest of the factors constant.
3.3. METHODOLOGY
To reach the purpose previously pointed out, firstly the size and shape distribution of
particles are analyzed. Secondly, viscosity of known products as mayonnaise, ketchup,
honey, oil and peanut butter are obtained with a Brookfield and a Paar Physica
rheometers. Posterior, based on the prototype clutch two kinds of experiments are
performed: first, the output angular speed of the clutch is measured by stages meanwhile
instead of the MR fluid, commercial known products are used. Afterwards, the results of
both experiments are compared to determine the viscosities of the MR fluid
approximating the results of these experiments with those obtain for the known products
in the rheometers. Finally, a constitutive model is developed throughout a mathematical
identification in function of the current and shear rate as independent variables and
viscosity as dependent variable.
3.4. SYSTEM DESCRIPTION
3.4.1. MRFLUID GENERAL DESCRIPTION
The MR fluid used for this analysis, MR-TECH® shown in figure 3.1., is mainly a
dispersion of iron powder 99.9%, as the soft magnetic material, in a carrier oil, and it was
developed at ITESM, Campus Monterrey. The iron particles distribution size has a mean
of 15.53µm at a standard deviation of 2.624µm and the particles are irregularly shaped.
Mass fraction of the solid phase is 60% and volume fraction is 25.62%. The kind of oil
used is commercial gasoline engine oil, SAE 40. When a magnetic field is applied the
fluid takes in separate from particles more than 24 hours. The viscosity of the MR fluid
varies from 800cP to 260000cP according to magnetic field applied.
3.4.2. EXPERIMENTAL ARRANGEMENT DESCRIPTION
A prototype actuator was specially designed for this work, as shown in figure 3.2. A
volume of 3ml. of MR fluid is needed to fill the space between the concentric cylinders.
The experimental arrangement developed is used to determine and to compare for
rheology purposes the clutch behavior with commercial products and MR fluid. The main
difference between such experiments is the use of the coil.
Figure 3.2 Prototype clutch design. (Concentric Cylinders)
The systems used for the experiments is composed by the following components and
presented in figure 3.3.
A coil has been designed to be capable of produce a magnetic field of 70.8kAm-1
at a current of 3ADC, and it was designed to be located around the side of the brake that
contains the MR fluid. Position A in Figure 3.3.
As figure 3.3 shown, a special body was designed to support both input (Position
The motor used for this works is a 1-HP Leeson Permanent Magnet DC Motor,
which is controlled by speed sensors and a laser stroboscope system was used for angular
[image:41.612.214.411.168.370.2]velocity measures.
Figure 3.3 Experimental arrangement. (A) Coil, (B) Input Shaft (C) Output Shaft
3.5. RESULTS
3.5.1 PARTICLE SIZE DISTRIBUTION AND SHAPE ANALYSIS
The particle size of the iron powder used for the MR fluid is determined with a
Laser Diffraction Particle Size Analyzer (LS 230) with an operating range between
0.04µm -2000µm. The particles are dispersed in ethylene glycol fluid and the results
obtained are shown in figure 3.4.
Posterior, the morphology of the iron particles is analyzed with a Scanning Electron
Microscope as shown in figure 3.5.
A
Figure 3.4 Iron powder particle size analysis
As can be seen from the results of size and shape analysis, the particles are non-uniform
and present a mean size of 15.54µm in their diameter and do not have a defined shape.
The addition of these rigid particles to the oil alters the flow field. This hydrodynamic
disturbance has an effect on viscosity. [3.3]
In addition to iron powder and the carrier oil, both surfactant and thixotropic agents are
used. The surfactant is used in order to prevent the particles from getting close to each
other that would cause agglomeration and the thixotropic agents are used in order to
retard particles settling.
3.5.2 RHEOLOGY ANALYSIS OF COMMERCIAL PRODUCTS
In this part of the project, the rheology properties of oil SAE 40, ketchup, honey,
chocolate syrup and peanut butter are analyzed. The results are obtained, as shown in
figure 3.6 and 3.7 using a concentric cylinder rheometer, Brookfield VT550 (figure 3.8)
and a Paar Physica rheometer , figure 3.9, for the peanut butter analysis. The information
obtained from this analysis is useful to compare the MR fluid viscosity behavior in a
The results showed that oil SAE 40 and Honey at room temperature shown a
Newtonian behavior. Meanwhile, chocolate syrup and ketchup also present a Newtonian
behavior but only at high shear rates. In the other hand, peanut butter has a shear thinning
[image:43.612.123.490.195.606.2]behavior due to its decrease in viscosity with shear rate.
0 20 40 60 80 100 120 140 160 180 200
1 10 100 1000
Shear Rate (1/s)
S h ea r S tre ss (P a) Ketchup Honey Syrup Chocolate SAE 40
Figure 3.6 Shear Stress-Shear rate relationships of commercial products
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
1 10 100 1000
Shear Rate (1/s)
V isc o si ty ( m P as ) Ketchup Honey Syrup Chocolate SAE 40
1 10 100 1000 10000 100000 1000000
0.1 1 10 100 1000
Shear Rate
V
is
co
si
ty (m
P
as)
S
h
ear stres
s(
P
a)
[image:45.612.102.522.86.309.2]Viscosity Shear Stress
Figure 3.8 Viscosity/Shear Stress-Shear rate peanut butter relationships.
[image:45.612.133.479.391.654.2]Figure 3.10 Paar Physica rheometer system.
3.5.3 RHEOLOGY ANALYSIS OF MAGNETORHEOLOGICAL FLUID
This part of the analysis is performed using the experimental system developed.
Due to system capabilities and project goals the experiments are performed at high shear
rates at the outer cylinder.
In the first part of these experiments, honey, ketchup, oil SAE 40, chocolate and
peanut butter are added to the prototype clutch, at room temperature and at different input
velocities. The results obtained are shown in figure 3.10.
For the following experiments, the prototype clutch is filled up with
magnetorheological fluid and the coil is positioned around clutch’s body. The
experiments are performed at different angular velocities and under different current
intensities. Meanwhile the current intensity is increased the output angular velocity also
0 50 100 150 200 250 300 350 400
0 200 400 600 800 1000
Input Speed (RPM)
[image:47.612.96.519.88.308.2]O u tp u t Spe ed ( R PM ) Honey Chocolate Peanut Butter Ketchup Oil SAE40
Figure 3.11 Prototype clutch experiments with commercial products.
0 50 100 150 200 250 300 350
0 200 400 600 800
Input Speed (RPM)
O u tp ut S p ee d (R P M ) 0.5 Ampere 1 Ampere 1.5 Ampere 2 Ampere 2.5 Ampere 3 Ampere
Posterior, both MR fluids and known products behavior has been compared
graphically. Also, two lines were added to represent the liquid and solid states. As can be
seen in figure 3.12, the analysis shows that at lower input speeds and higher magnetic
fields the MR fluid viscosity is closer to the solid state and at higher input speeds; even
under higher magnetic fields the viscosity of the fluid is smaller.
0 100 200 300 400 500 600 700 800
0 200 400 600 800 1000
Input Speed (RPM)
O u tput Spee d ( R PM
) 140 Gauss
[image:48.612.99.460.227.421.2]290 Gauss 440 Gauss 590 Gauss 740 Gauss 890 Gauss Honey Chocolate Peanut Butter Liquid Solid
Figure 3.13 MR fluid viscosity behavior analysis.
Fundamental model expressions, adjusted to the experiment carried out, to
determine the viscosity of MR fluids in concentric cylinders, are shown in equations 3.1
to 3.3, according to the models presented by Bird [3.5]:
Velocity profile, (3.1) 2 1 1 2 2 1 1 n i k
V o i R
n r
r o i
Shear rate,
(3.2)
And shear stress,
(3.3)
Where, Ωi and Ωo are the input and outer angular speeds in rad/seg respectively, k
is the ratio (r/R) of concentric cylinders radii and, m and n, are constants that depend of
the material.
Torque measurements are necessary to determine MR fluid viscosities at different
magnetic fields and completely characterize the fluid. Future work is required to obtain
this measure and obtain viscosity values.
The fundamental constitutive equation to characterize the viscosity of the MR
fluid can be defined by equation 3.4
o MG
η η= +η (3.4)
Where ηo is the “initial” viscosity of the MR fluid or the viscosity when no
magnetic field is applied and ηMG is the increment in the viscosity due to the magnetic
field applied.
For suspensions, Einstein found the extra energy dissipated by adding one particle
to the fluid per unit volume [3.3]. Then, assuming no interactions “initial” viscosity can
be determined by equation 3.5:
2 ( ) 2 2 1 1 n
R o i
r n r
(
1 k)
o s E
η =η + φ (3.5)
Where
η
o is the viscosity of the suspension andη
s is the viscosity of the carrierliquid, kE is a coefficient which refers to particles interactions and
φ
is the volumefraction of the dispersed phase. Assuming no interactionskE =2.5, it is obtained equation
3.6:
5 1
2
o s
η =η ⎛⎜ + φ⎞⎟
⎝ ⎠ (3.6)
Based on the rheology analysis of commercial products it is know that the carrier
liquid, oil SAE 40, has a viscosity of 439.72 mPas. In the other hand, it is also know that
the volume fraction of the iron particles is 25.62% and therefore according to equation
3.2, the viscosity of the MR fluid at zero shear rate is approximately 721.36mPas.
3.6. CONCLUSIONS
An MR fluid characterization is shown, the particle size and shape analysis along
with the carrier oil rheology properties and the chemical additives used in the
development of the MR fluid are described.
By the use of the data obtained from rheometers equipment for known products, it
has been possible to establish a relation between the viscosity reported on it and the
behavior observed in the concentric cylinders by means of the input and output speeds.
Based on the concentric cylinder principle, an actuator device has been specially
designed and constructed to determine the viscosity behavior of the MR fluid under
different magnetic field intensities. Fundamental constitutive models expressions to
determine the viscosity of MR fluids based on the experiments carried out have been
3.7. REFERENCES
3.1 Qing Sun, et al, “An adaptive beam model and dynamic characteristics of
magnetorheological materials”, Journal of Sound and Vibration, 261, pp.
481, 2003.
3.2 Vessonen, Ismo, “ Smart Materials and Structures”. VTT Symposium 225, pp.
7-19, 2003
3.3 Macosko, Christopher, “Rheology. Principles, measurements and
applications”. Wiley-VCH: New York, 1994.
3.4 E. Yu. Taran, et al, “Features of magnetorheology of suspension with the
Cowin polar carrier fluid”, Journal of Magnetism and Magnetic Materials, 252, pp. 229-231, 2002.
4. C
HARACTERIZATION,
M
ODELING ANDS
IMULATION OFM
AGNETORHEOLOGICALC
LUTCHS
YSTEM TOD
EVELOP AR
ECONFIGURABLED
EVICE4.1. INTRODUCTION
Magnetorheological (MR) fluids belong to the general class of smart materials
whose rheological properties can be modified by applying a magnetic field [4.1]. Their
efficiency is firstly judge through its yield stress, τy, which measures the strength of the
structure formed by the application of the field [4.2]. MR brakes, clutches and actuators
are being developed taking advantage of this property and are important for improving
the function and performance of automotive and mechatronics system [4.3]. In the other
hand, the use of dynamic simulations is helpful in order to investigate interaction factors
and to reduce lengthy prototype test programs [4.4].
4.2. PURPOSE
MR actuators systems have been studied recently. Its ability to produce high
torque, low inertia, safe device and simple interface has been exploited for automotive
and exercise equipment applications. Even though, nowadays some of these applications
are currently being developed, and few have reached the commercial stage [4.3-4.6]. This
chapter has the purpose of characterize, identify the mathematical model and simulate the
behavior of a magnetorheological fluid in a reconfigurable clutch system.
4.3. METHODOLOGY
To reach the purpose previously pointed out, firstly, the characterization is made
by means of experimentation and by using a prototype brake. The angular speed of the
brake is measured by stages meanwhile known speeds are applied under the influence of
different magnetic fields. Posteriorly, the model is developed throughout the
mathematical identification of the relationship Current-OutputSpeed-InputSpeed
as dependent variables. Finally, the simulation is carried out in two parts. Part one; uses a
program in which the mathematical model is applied in order to adjust the MR clutch
behavior based on input current and according to different speed requirements. And part
two; the brake resistance is read by the module ADAMSVIEW of MSC ADAMS
software in which a clucth system has been modeled for describing the brake behavior at
different virtual conditions.
4.4. SYSTEM DESCRIPTION
The MR fluid used for this analysis, MR-TECH® shown in figure 4.1-a, is mainly a
dispersion of iron powder 99.9%, as the soft magnetic material, in a carrier oil, and it was
developed at ITESM, Campus Monterrey. The iron particles distribution size has a mean
of 15.53µm at a standard deviation of 2.624µm and the particles are irregularly shaped.
A prototype cluctch was specially designed for this work, as shown in figure 4.1-b. A
volume of 3ml. of MR fluid is needed to fill the space between the concentric cylinders.
(a)
(b) (c)
[image:53.612.131.468.431.681.2]The system used for the experiments is composed by the following components and
[image:54.612.240.383.151.360.2]presented in figure 4.2.
Figure 4.2 Experimental arrangement: (A) Coil, (B) Input Shaft (C) Output Shaft
A coil has been designed to be capable of produce a magnetic field of 70.8kAm-1
at a current of 3ADC, and it was designed to be located around the side of the clutch that
contains the MR fluid. Position A in Figure 4.2.
As figure 4.2 shown, a special body was designed to support both input (Position
B) and output shafts (Position C).
The motor used for this works is a 1-HP Leeson Permanent Magnet DC Motor,
which is controlled by speed sensors and a laser stroboscope system was used for velocity
feedback.
The module ADAMSVIEW of MSC Software is used to create a virtual prototype
of an actuator system and to view key physical measures that emulate the data normally
produced physically.
A B
MR actuator applications exploit the torque transfer capabilities of these materials
when placed between concentric cylinders or parallel disks. Such geometry is been used
in MR clutches and brakes. Consider concentric cylinders with the space between the
filled with an MR fluid. When one of the cylinders rotates with no magnetic field applied,
little torque is transmitted to the second cylinder. However, when a field is applied to the
fluid to make it much more viscous, a considerable fraction of the torque applied to the
first cylinder can be transmitted to the second. In some cases, a sufficiently large field
can cause the fluid to effectively solidify, making the second cylinder rotate with the
same angular speed as the first [4.3]. In figure 4.3 and 4.4 it is possible to observe the
differences in the velocity profile of a MR fluid in concentric cylinders both without and
with a magnetic field applied. It is seen that when a magnetic field is applied the velocity
[image:55.612.187.430.365.584.2]profile has been reduced what implies a viscosity change and a greater torque transmitted.
Figure 4.3. MR fluid behavior inside concentric cylinders without magnetic field applied. (Adapted from Bird, 2003)
V?
Inner fixed cylinder
Velocity profile
Oo
R
KR Outer Rotatory
Figure 4.4. MR fluid behavior inside concentric cylinders when a magnetic field is applied. (Adapted from Bird, 2003)
4.5. RESULTS
4.5.1. Characterization of MR Brake
Experimental Work. The characterization of the magnetorheological clutch has
been done to obtain an expression, which represents its performance capabilities under
different magnetic fields. Such expression lets establish the way in which a controllable
brake system can be fully used.
Firstly, it is necessary to get the set of data for the determination of
Current-Output*Speed-Input*Speed relationship. The brake is fixed and the input shaft was fixed
to the motor; meanwhile a coil is located around the brake body, as shown in figure 4.2.
The tests were done at different angular speeds and different electric current intensities
that vary from 0.5 to 3 Amperes. The relationship obtained by experiments is shown in
figure 4.3.
V?
Inner fixed cylinder
Velocity profile
Oo
R
KR Outer Rotatory
4.5.2. Mathematical Identification
Mathematical Identification. The Current-Output Speed-Input Speed relationship is
obtained directly from the tests done.
The constitutive model is obtained by mathematical identification of the
relationship found (figure 4.5). Firstly, sigmoidal equations, represented by equation 4.1,
were found by means of a nonlinear regression model.
1
d
Os gI
fe
= −
+ (4.1)
Where,
O
s is the output speed, I the current applied and d, f and g are constants,which values are presented in table 4.1 according to input speed.
-50 0 50 100 150 200 250
0 0.5 1 1.5 2 2.5
[image:57.612.103.520.383.649.2]Current (A) O u tp u t S p ee d (R P M ) 100 RPM 150RPM 200RPM 250RPM 300RPM
Table 4.1 Constant values of equations found.
Input Speed Constants
d 76.24
f 1687.86
100 RPM
g 5.27
d 97.39
f 134.68
150 RPM
g 3.19
d 126.69
f 342.77
200 RPM
g 3.99
d 166.84
f 200.86
250 RPM
g 3.39
d 209.51
f 525.31
300 RPM
g 4.2
Posterior, a unique equation in function of the magnetic field (MF), Gauss (G),
which characterizes all system is needed. Due to its sigmoidal form, the function was
approximate to equation 4.2:
1 1 G O S G c β − = +
⎛
⎛
⎞
⎞
⎜
⎜
⎟
⎟
⎜
⎜
⎟
⎟
⎜
⎝
⎠
⎟
⎝
⎠
(4.2)Where
β
is a material constant and Gc is the characteristic current, which isdefined by the inflection point of curve.
Because equation 4.2 works with values between 0 and 1, the next step was to
normalized both the magnetic field and the output speed dividing the different values by
the corresponding highest value. The respective information was plotted and presented in
0 0.2 0.4 0.6 0.8 1 1.2
0 0.2 0.4 0.6 0.8 1 1.2
Normalized Magnetic Field (%Gauss)
[image:59.612.130.490.108.312.2]N o rm al iz ed S p eed ( % 0s) 100 RPM 150RPM 200 RPM 250 RPM 300 RPM
Figure 4.6 Magnetic field and output speed normalized curves.
With the set of data obtained until this moment, it was determined both the
respective inflection point, %Gc =0.49, and by the least square method the constant
β
,β
= -6.45, of equation 4.1. Once all values are settled, equation 4.3 was defined:
1 1
-6.45
% %
% 1 1
% 0.49 G G OS Gc
β
⎛ ⎛ ⎞ ⎞ ⎛ ⎛ ⎞ ⎞ ⎜ ⎜ ⎟ ⎟ ⎜ ⎜ ⎟ ⎟ ⎜ ⎜ ⎟ ⎟ ⎜ ⎟ ⎜ ⎝ ⎠ ⎟ ⎝ ⎝ ⎠ ⎠ ⎝ ⎠ − − = + = + (4.3)Finally, according to the current and output speed percentage it is possible to
determine the magnetic field needed and the output speed obtained according to the input
speed. Table 4.3 presents the constant values needed to multiply %G and %OS to obtain
Table 4.2 Constant values needed to obtain the current and output speed conditions.
Input
Speed Normalizad MF Normalized Speed 100 %G*890 %OS*76
150 %G*890 %OS*97
200 %G*890 %OS*128
250 %G*890 %OS*165
300 %G*890 %OS*209
A comparative analysis between the model and experimental data has been carried
out and is shown below.
-50 0 50 100 150 200 250
0 200 400 600 800
Magnetic Field (G)
Outp ut Sp eed (RPM) 100 RPM 150RPM 200RPM 250RPM 300RPM Model 100RPM Model 150RPM Model 200RPM Model 250RPM Model 300RPM
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