MR Fluids- Overview, Definitions, Working, Applications and more

This presentation consists of overview, applications, working and applications of Magneto Rheological (MR) Fluids

1. M agnetorheological Fluid   Peeyush Mishra B191265MT Material Science and Engineering 1

2. Discovered by Rabinow in 1940s at US National Bureau of Standards MR Dampers currently being used in Dongting bridge, China Famously used in suspension of the 2002 model of the Cadillac Seville STS automobile and more recently, in the suspension of the second-generation Audi TT. Background 2

3. Smart Fluids By using magnetic or electric field, it is possible to change properties of fluid The most developed smart fluids today are fluids whose viscosity increases when a magnetic field is applied. Electrorheological or ER fluids are another type of smart fluid in which the resistance to flow can be changed quickly and drastically by an applied electric field. In the presence of an electric field, other smart fluids modify their surface tension. This technique has been used to create extremely small, controlled lenses. 3

4. Introduction 4

5. Introduction A Magneto-Rheological fluid (MR Fluid) is a type of smart fluid in a carrier fluid, usually a type of oil. Viscosity increases, with application of magnetic field, and thus becomes a viscoelastic solid It is a Newtonian fluid in off state and Non-Newtonian fluid in on state By adjusting the magnetic field intensity, the yield stress of the fluid in its active ("on") state may be regulated very precisely. 5

6. Composition Carbonyl Iron Particles: These soft iron particles, which are only 3 to 5 micrometers in diameter, make up 20 to 40% of the fluid(different from Ferro particles). Carrier Liquid: The iron flakes are suspended in a liquid, most often hydrocarbon oil. Proprietary Additives: These chemicals are used to prevent the iron particles from settling due to gravity. 6

7. Working of MR Fluid These are the fluids that change their properties when we apply a magnetic field to them When the magnet is in place of MR fluid, it turns into a solid When the magnet is removed from the solid, it instantly reverses into liquid 7

8. Working Fig a) shows the random distribution of magnetic particles in MR fluid. Fig b) shows the behaviour of magnetic particles in a magnetic field 8

9. Characteristics of MR Fluid Properties of MR Fluid Typical Value Initial Viscosity 0.2 – 0.3 [Pa-s] (at 25 °C ) Density 3 – 4 [g/cm3 ] Magnetic Field Strength 150 – 250 [kA/m] Yield Point 50 – 100 [kPa] Reaction Time Few milliseconds Supply Voltage and Current Intensity 2– 25 V, 1–2 A Work Temperature Range -50 to 150 [ °C ] The rheological characteristics of MR fluids are primarily determined by particle size, concentration, density, and additives. Magnetic properties can also be used to assess the nature and creation of particle structure within the fluid. 9

10. Bingham plastics Bingham plastics is used to describe fundamental field dependent fluid characteristics in most engineering applications. Shear stress is directly proportional to shear strain in a Bingham plastic, which is a Non-Newtonian fluid whose yield stress must grow before flow can commence. The overall yield stress is calculated as follows: 10

11. Modes of Operation Flow Mode Shear Mode Squeeze Mode 11

12. Flow Mode Both plates are stationary Fluid is located between these stationary plates Magnetic field is perpendicular to the direction of flow Application: Dampers, MR Valve and shock absorbers 12

13. Shear Mode In this mode, one plate is stationary and the other plate is moving In this mode also, magnetic field is perpendicular to direction of flow of fluid Shear mode is generally used to control rotational motion Applications: Clutches and Brakes 13

14. Squeeze Mode In this mode, one plate is moving relative to other, perpendicular to its plate In this mode also magnetic field is perpendicular to direction of flow of fluid This mode is used in controlling small, millimetre-order movement but involving heavy force 14

15. Applications Mechanical Engineering Optics Automobile Engineering Military and Defence House hold applications 15

16. Vehicle Suspension Damper The MR fluid is driven across a built-in MR valve in the MR damper. The MR damper's piston functions as an electromagnet with the needed number of coils to generate the required magnetic field. The MR damper also incorporates a run-through shaft to eliminate the need for an accumulator. 16

17. MR Transmission Clutches They are used to transmit torque from the engine to the transmission and the car in the automobile power train. The MR sponge clutch can be utilized to offer vehicle launch control, resulting in a smooth vehicle launch. As a result, the MRF clutch may be used to replace conventional torque converters, resulting in improved fuel economy. 17

18. MR Damping in Washing Machine During the spin cycle of a household washing machine, a variable damping system based on magnetorheological fluid sponges can help manage the vibratory motion. Damping is turned on as the drum approaches resonance and turned off at the fastest speeds for the best vibration isolation. The method allows the drum to rotate at high enough speeds to act as a centrifuge, but without the violent shaking that every user is accustomed with. 18

19. MR Technology used in Prosthetic Limbs Biedermann Motech, a German maker of prosthetic components, collaborated with design engineers to create a device that increases the mobility of above-the-knee leg amputees. The ProliteTM Smart MagnetixTM Above-the-Knee (AK) Prosthetic uses controlled MR technology developed from the LORD Motion MasterTM Ride Management System truck seat damper to improve gait balance, stability, and energy efficiency. IoT makes it even more effective 19

20. MR Fluid in Seismic and Wind Mitigation Civil engineers are applying MR Technology into the structural engineering of buildings and bridges in the construction sector. A dampening system using MR fluid dampers protects the structure against earthquakes and windstorms in the same way as an automotive shock absorber does. 20

21. Other Applications Military and Defense: The Army Research Office in the United States is now financing research into the use of MR fluid to improve body armor. Researchers estimated that making the fluid bullet resistant would take five to ten years in 2003. Dynamic MR shock absorbers and/or dampers are also used in HMMWVs and other all-terrain vehicles. Optics : Magnetorheological finishing, a magnetorheological fluid-based optical polishing technology, has shown to be extremely accurate. It was utilized to make the corrective lens for the Hubble Space Telescope. Aerospace : In the case of a crash, magnetorheological dampers are being developed for use in military and commercial helicopter cockpit seats as safety mechanisms. They would be used to reduce the amount of stress imparted to a passenger's spinal column, lowering the risk of lasting harm in the event of a collision. 21

22. MR Fluid vs ER Fluid? MR Fluids can change their rheological properties far easily than ER Fluids MR fluids can be used in dirty or humid atmosphere since they are less sensitive to moisture and contaminants Power and voltage required as compare to ER fluid are less for MR fluid MR fluid does not affected by surface chemistry of surfactant used. 22

23. Advantages Easy to control It is a high quality fluid Higher magnitude of yield stress Fast response Low power requirement 23

24. Disadvantages They are heavy due to their high density, which is caused by the presence of iron. However, because operational quantities are minimal, this is not an insurmountable barrier. High quality fluids are costly. After a long period of use, fluids thicken and must be replaced. For some applications, Ferro-particle settling can be an issue. Extremely high/low temperatures make it impossible to operate. 24

25. Conclusion The MR Fluid, will replace the conventional based mechanisms, and it also improves in cost reduction and functionality of the system. MR Fluid has a wide range of applications and there is a lot of future scope for these technology. 25

26. References Emerging Trends in Mechatronics: Edition-1 Wiley Publications (Aydin Azizi) ( Published-2020) Magnetorheological Fluid- A review on characteristics devices and applications- Gaurish A Walke & Amol Patil(Published-2019) Magnetorheological Fluid and its Applications by Pranav Gadekar , V.S.Kanthale and N.D.Khaire (Released-2017) https://www.researchgate.net/publication/322077004_Magnetorheological_Fluids_and_Its_Applications_Current_Scenario_and_Future_Prospects- Hanmanth Saluke & Surendra Thikane (Released in 2017) 26

27. Any Queries? 27