Fundamental Constitutive Modeling of Magnetorheological Fluid and its Application on Reconfigurable Systems Semi active Damper and Transmission Actuator

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(1)INSTITUTO TECNOLÓGICO Y D E ESTUDIOS 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-. TESIS PRESENTADA COMO REQUISITO PARCIAL PARA OBTENER EL GRADO ACADÉMICO DE: MAESTRO EN CIENCIAS ESPECIALIDAD EN SISTEMAS DE MANUFACTURA. POR:. LEOPOLDO SALVADOR VILLARREAL GONZÁLEZ. MONTERREY, N. L., MÉXICO. MAYO,. 2005..

(2) INSTITUTO TECNOLÓGICO Y DE ESTUDIOS SUPERIORES DE MONTERREY CAMPUS MONTERREY DIVISIÓN DE INGENIERÍA Y ARQUITECTURA PROGRAMA DE GRADUADOS EN INGENIERÍA Los 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 COMITÉ DE TESIS. ______________________________ Dr. Jorge Armando Cortés Ramírez. ASESOR. ____________________________ Dr. Jaime Bonilla Ríos CO-ASESOR. __________________________ Dr. Ciro A. Rodríguez González SINODAL. APROBADO. __________________________________ Dr. Federico Viramontes Brown. Director del Programa de Graduados en Ingeniería. Mayo, 2005.

(3) DEDICATED TO. A DIOS A MI ESPOSA, GRACIAS POR TU APOYO, AMOR Y CONFIANZA. NADIA GRACIAS POR SER PARTE DE MI VIDA Y COMPARTIR CONMIGO ESTE SUEÑO.. A MI PAPÁ, GRACIAS POR TU APOYO Y POR SER MI GRAN EJEMPLO DE DEDICACIÓN, ESFUERZO Y HONESTIDAD.. A MI MAMÁ, GRACIAS POR TU APOYO INCONDICIONAL, POR SER MI AMIGA Y POR CREER SIEMPRE EN MI.. GRACIAS PAPÁS POR LOS VALORES QUE ME INCULCARON, POR LA EDUCACIÓN QUE ME BRINDARON, POR SUS ORACIONES Y PORQUE GRACIAS A DIOS Y A USTEDES HE ALCANZADO ESTA META.. A MI SIS, POR TODO SU APOYO Y CARIÑO. POR SER EJEMPLO Y MOTIVACIÓN EN LA LUCHA POR ALCANZAR NUESTROS SUEÑOS.. A MI PAPA TOÑO, PORQUE OFRECÍ MI TRABAJO POR TÍ Y PORQUE GRACIAS A DIOS, HOY COMPARTES CONMIGO ESTE NUEVO TRIUNFO.. I.

(4) ACKNOWLEDGEMENTS A 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 Dr. Arturo Molina.. II.

(5) FOR THE READER The 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 based on the global methodology defined for the thesis.. III.

(6) ABSTRACT Magnetorheological (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 of reconfigurable systems.. IV.

(7) LIST OF FIGURES Figure 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. 37. applied…...................................................................................................... Figure 4.4. MR fluid behavior inside concentric cylinders with magnetic field. 38. applied……………………………………………………………………. 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 4.9 Contact modification window……………………………………………... 44. VIII.

(8) 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. LIST OF TABLES Table 2.1 MR fluids Area-Application relationship…………………………………... 11. Table 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. Table 4.2 Constant values needed to obtain the current and output speed conditions………………………………………………………………….... IX. 42.

(9) INDEX DEDICATED 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.. System Description……………………………………………………. 21. V.

(10) 3.5.. 3.4.1. MR Fluid General Description………………………………... 21. 3.4.2. Experimental Arrangement Description………………………. 22. 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. 5.5.2. Mathematical Identification………………………………….... 50. VI.

(11) 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 Vita……………………………………………………………………………………. 65. VII.

(12) 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. LIST OF TABLES Table 2.1 MR fluids Area-Application relationship…………………………………... 11. Table 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. Table 4.2 Constant values needed to obtain the current and output speed conditions………………………………………………………………….... IX. 42.

(13) SYMBOLOGY ER. 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. OS. Clutch Output Speed. X.

(14) β. Clutch general curve constant value. G. Gauss. GC. Characteristic Magnetic Field. RPM. Revolution per minute. η. Viscosity of the suspension. ηs. Viscosity of the carrier liquid. φ. Volume fraction of the dispersed phase. kE. Coefficient which refers to particles interactions. SR. Speed Rate. Ω. Angular velocity. γ. Shear rate. XI.

(15) CHAPTER 1. BACKGROUND AND AIMS. 1. BACKGROUND AND AIMS 1.1. 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. •. Additives. • Materials characterization. •. Recycling. • Materials Modeling and prediction 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. Conversion. of. Information. Knowledge. •. Concurrent Manufacturing. •. Environmental Compatibility. •. Innovative Processes. •. Reconfigurable Enterprise. 1. to.

(16) Chapter I. BACKGROUND AND AIMS. 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 modular machines, modular processes, and modular tooling. So that, the development. 2.

(17) Chapter I. BACKGROUND AND AIMS. and implementation of key interrelated technologies to achieve the goals of reconfigurable manufacturing systems are needed.. 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 the design of reconfigurable system devices. [1.6-1.7].. 3.

(18) Chapter I. BACKGROUND AND AIMS. Reconfiguration Process. System. Machine. Software. Control 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.. 4.

(19) Chapter I. BACKGROUND AND AIMS. 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. •. Analyze MR fluid viscosity at different magnetic field intensities. 5.

(20) Chapter I. BACKGROUND AND AIMS. 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 presented.. 6.

(21) Chapter I. BACKGROUND AND AIMS. 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, pp. 229-231, 2002.. 7.

(22) Chapter 2. STATE OF THE ART. 2. STATE OF THE ART. 2.1. 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 nonconducting 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 have been equally strong as Rabinow’s MR fluid. A typical fluid described by Winslow. 8.

(23) Chapter 2. STATE OF THE ART. 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 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 get past the point of novelty [2.5].. 9.

(24) Chapter 2. STATE OF THE ART. 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 damper applications especially for Civil Engineering and Automotive/Machine areas.. 10.

(25) Chapter 2. STATE OF THE ART. Table 2.1 MR fluids Area-Device relationship. Area Device. Manufacture. Automotive and Machines. Medicine Civil Engineering Optics Mechatronics. Adaptive structure. [2.18] [2.6], [2.8], [2.9], [2.10], [2.11], [2.12], [2.17], [2.19], [2.21], [2.24]. Damper. Polisher. [2.7]. [2.13], [2.23],[2.25], [2.26] [2.14], [2.27]. [2.27]. Actuator. [2.16], [2.20]. [2.1]. [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 Brakes Clutch Coupling Device MR Fluid Materials Polishing Gripping/ Holder Hydraulic Mount Mitigate Chatter Vibration Torque Transfer Valve Others. 11. 78 6 19 4 36 15 5 3 2 10 8 49.

(26) Chapter 2. STATE OF THE ART. 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 the next ten years [2.28].. 12.

(27) Chapter 2. STATE OF THE ART. Damper. Suspension Seats. Actuator. Clutch Brakes. Damper. Structures Buildings Bridges. Shock Absorber. Blast resistant and structural. Adaptive Structure. Structures. Damper. Above Knee Prosthesis. Automotive. Civil Engineering. MR FLUID. Medical Haptic Sensor-Actuator Actuator. Manufacture. Polisher. Silicon Wafers (Semiconductors) Miniaturized Parts. Actuator. Hydraulic Mount Gripping/Holder. Chatter Mitigation. Optical Mechatronics. Polisher. Machining. Lenses. Valves. Micromachines. Actuator. Mechatronics systems. Figure 2.2 MR Fluid taxonomy from the point of view: area-device-application.. 13.

(28) Chapter 2. STATE OF THE ART. 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 important part in manufacture activities, especially as actuator or in chatter mitigation.. 14.

(29) Chapter 2. STATE OF THE ART. Finally, it is expected that smart materials, particularly MR fluids, will have a preponderant participation in the development of Reconfigurable Manufacturing Systems (RMS).. 15.

(30) Chapter 2. STATE OF THE ART. 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. 5568, 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 SemiActive ER/MR Fluid Dampers”, Proceedings of SPIE Conference on Smart Materials and Structures, Vol. 4331, pp. 82-91, 2001.. 16.

(31) Chapter 2. STATE OF THE ART. 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 elastography and electrorheological fluids for virtual reality applications in medicine”, International Congress Series, pp. 1354, 2003.. 17.

(32) Chapter 2. STATE OF THE ART. 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. 465481, 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 vehicle suspension system”, Mechatronics, Vol. 12, pp. 963-973, 2002.. 18.

(33) Chapter 2. STATE OF THE ART. 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. http://www.nap.edu/readingroom/books/visionary/. 19.

(34) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION 3.1.. 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 known speeds are applied under the influence of different magnetic fields and, second,. 20.

(35) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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. MR FLUID 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.. Figure 3.1 MR fluid. 21.

(36) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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 B) and output shafts (Position C).. 22.

(37) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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 velocity measures.. C. A B. 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.. 23.

(38) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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 posterior experiment.. 24.

(39) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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 behavior due to its decrease in viscosity with shear rate.. Figure 3.5 Iron Powder Micrographs. 25.

(40) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 200 180 Shear Stress (Pa). 160 140 Ketchup. 120. Honey. 100. Syrup Chocolate. 80. SAE 40. 60 40 20 0 1. 10. 100. 1000. Shear Rate (1/s). Viscosity (mPas). Figure 3.6 Shear Stress-Shear rate relationships of commercial products. 10000 9000 8000 7000 6000 5000 4000 3000 2000 1000 0. Ketchup Honey Syrup Chocolate SAE 40. 1. 10. 100. 1000. Shear Rate (1/s). Figure 3.7 Viscosity-Shear rate relationships of commercial products. 26.

(41) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 1000000. Viscosity (mPas) Shear stress(Pa). 100000 10000 Viscosity Shear Stress. 1000 100 10 1 0.1. 1. 10. 100. 1000. Shear Rate. Figure 3.8 Viscosity/Shear Stress-Shear rate peanut butter relationships.. Figure 3.9 Brookfield rheometer system.. 27.

(42) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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 changes as figure 3.11 shown.. 28.

(43) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. Output Speed (RPM). 400 350 300 250. Honey. 200. Chocolate. 150. Peanut Butter Ketchup. 100. Oil SAE40. 50 0 0. 200. 400. 600. 800. 1000. Input Speed (RPM). Figure 3.11 Prototype clutch experiments with commercial products.. Output Speed (RPM). 350 300 250. 0.5 Ampere. 200. 1 Ampere 1.5 Ampere. 150. 2 Ampere. 100. 2.5 Ampere 3 Ampere. 50 0 0. 200. 400. 600. 800. Input Speed (RPM). Figure 3.12 Prototype clutch experiments with MR fluid.. 29.

(44) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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. Output Speed (RPM). under higher magnetic fields the viscosity of the fluid is smaller.. 140 Gauss. 800 700 600 500 400 300 200 100 0. 290 Gauss 440 Gauss 590 Gauss 740 Gauss 890 Gauss Honey Chocolate Peanut Butter Liquid. 0. 200. 400. 600. 800. 1000. Solid. Input Speed (RPM). 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, ⎡ 2 ⎤⎤ ⎡ ⎢ ⎢⎛ 1 ⎞ n ⎥ ⎥ Ωi ⎢⎜ ⎟ −1⎥ ⎥ ⎢ 2 ⎢ ⎢⎝ k ⎠ ⎥⎥ Vθ Ωo −Ωi ⎢⎛ R ⎞ ⎣ ⎦ ⎥ n = + 2 ⎤ ⎢⎜⎝ r ⎟⎠ Ωo −Ωi ⎥ r ⎡ ⎥ ⎢⎛ 1 ⎞ n ⎥ ⎢ ⎥ ⎢⎜ ⎟ −1⎥ ⎢ ⎥ ⎢⎝ k ⎠ ⎥⎢ ⎣ ⎦ ⎣⎢ ⎦⎥. (3.1). 30.

(45) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. Shear rate, 2 2 ⎛ R ⎞ n (Ωo − Ωi ) γrθ = − ⎜ ⎟ 2 ⎤ n⎝ r ⎠ ⎡ ⎢⎛ 1 ⎞ n ⎥ ⎢⎜ k ⎟ − 1⎥ ⎢⎝ ⎠ ⎥ ⎣ ⎦. (3.2). And shear stress, σ rθ = −mγrθ n. (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 (3.4). η = ηo + η MG. 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:. 31.

(46) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. (. ηo = η s 1 + k E φ. ). (3.5). Where ηo is the viscosity of the suspension and ηs is the viscosity of the carrier liquid, kE is a coefficient which refers to particles interactions and φ is the volume fraction of the dispersed phase. Assuming no interactions kE = 2.5 , it is obtained equation 3.6:. ⎛ ⎝. 5 ⎞ ⎠. ηo = η s ⎜ 1 + φ ⎟ 2. (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 developed, equations 3.1 to 3.4.. 32.

(47) Chapter 3. MAGNETORHEOLOGICAL FLUID CHARACTERIZATION. 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. 465481, 2003.. 3.2. Vessonen, Ismo, “ Smart Materials and Structures”. VTT Symposium 225, pp. 7-19, 2003. 3.3. Macosko, Christopher, “Rheology. Principles, 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.. 3.5. Bird, et al., “Fenómenos de transporte”, Reverté: México, 2003.. 33. measurements. and.

(48) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. 4. CHARACTERIZATION, MODELING AND SIMULATION OF MAGNETORHEOLOGICAL CLUTCH SYSTEM TO DEVELOP A RECONFIGURABLE DEVICE 4.1.. 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. expressions are derived in function of electrical current as independent variable and speed. 34.

(49) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. 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). Figure 4.1 (a)Magnetorheological fluid , (b) prototype clutch damper and (c) cut view. 35.

(50) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. The system used for the experiments is composed by the following components and presented in figure 4.2.. B. A C. 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.. 36.

(51) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. 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 profile has been reduced what implies a viscosity change and a greater torque transmitted.. Outer Rotatory cylinder. V?. Velocity profile. Oo. Inner fixed cylinder. KR. R. Figure 4.3. MR fluid behavior inside concentric cylinders without magnetic field applied. (Adapted from Bird, 2003). 37.

(52) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. Outer Rotatory cylinder. V?. Velocity profile. Oo. Inner fixed cylinder. KR. R. 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 CurrentOutput*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.. 38.

(53) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. 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.. d Os = 1+ fe− gI. (4.1). Where, Os 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.. 250. Output Speed (RPM). 200. 150 100 RPM 150RPM 200RPM. 100. 250RPM 300RPM 50. 0 0. 0.5. 1. 1.5. 2. 2.5. -50 Current (A). Figure 4.5 Experimental relationship: Current-Output Speed according to input speed.. 39.

(54) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. Table 4.1 Constant values of equations found. Input Speed d f g d f g d f g d f g d f g. 100 RPM. 150 RPM. 200 RPM. 250 RPM. 300 RPM. Constants 76.24 1687.86 5.27 97.39 134.68 3.19 126.69 342.77 3.99 166.84 200.86 3.39 209.51 525.31 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:. O S. ⎛ ⎛ G ⎜ = 1+ ⎜ ⎜ ⎜G ⎜ ⎝ c ⎝. ⎞ ⎟ ⎟ ⎠. β ⎞−1. ⎟ ⎟ ⎟ ⎠. (4.2). Where β is a material constant and Gc is the characteristic current, which is defined 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 figure 4.6.. 40.

(55) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. Normalized Speed (%0s). 1.2 1 100 RPM. 0.8. 150RPM 200 RPM. 0.6. 250 RPM. 0.4. 300 RPM. 0.2 0 0. 0.2. 0.4. 0.6. 0.8. 1. 1.2. Normalized Magnetic Field (%Gauss). 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:. ⎛ β ⎛ %G ⎞ %OS = ⎜⎜1+ ⎜⎜ ⎟ ⎜ ⎝ %Gc ⎟⎠ ⎝. ⎞ ⎟ ⎟⎟ ⎠. −1. -6.45 ⎞ ⎛ ⎛ %G ⎞ ⎟ = ⎜1+ ⎜ ⎜ ⎝ 0.49 ⎟⎠ ⎟ ⎝ ⎠. −1 (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 such values.. 41.

(56) Chapter 4. CHARACTERIZATION, MODELING AND SIMULATION OF MR CLUTCH. Table 4.2 Constant values needed to obtain the current and output speed conditions.. Input Speed 100 150 200 250 300. Normalizad Normalized MF Speed %G*890 %OS*76 %G*890 %OS*97 %G*890 %OS*128 %G*890 %OS*165 %G*890 %OS*209. A comparative analysis between the model and experimental data has been carried out and is shown below.. 250. 200. Output Speed (RPM). 100 RPM 150RPM 150. 200RPM 250RPM 300RPM. 100. Model 100RPM Model 150RPM Model 200RPM. 50. Model 250RPM Model 300RPM 0 0. 200. 400. 600. 800. -50. Magnetic Field (G). Figure 4.7 Model and experimental data comparative analysis.. 42.