Shear Behavior of Magnetorheological Fluid and its effect on MR brake performance

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1 Internatinal Jurnal f Current Engineering and Technlgy E-ISSN , P-ISSN INPRESSCO, All Rights Reserved Available at Research Article Shear Behavir f Magnetrhelgical Fluid and its effect n MR brake perfrmance Chiranjit Sarkar Mechanical Engineering Department, Delhi Technlgical University, Shahbad Daluatpur, Bawana Rad, Delhi , India Accepted 08 April 2015, Available nline 14 April 2015, Vl.5, N.2 (April 2015) Abstract The aim f this paper is review the viscsity f magnetrhelgical (MR) fluid as functin f shear rate. The different rhelgical mdels f shear stress as a functin f shear rate have been reviewed. MR fluid has been characterized at varius shear rates fr different magnetic fields t bserve the shear behavir f MR fluid. In rder t cnfirm the shear behavir f MR fluids, experiments have been cnducted in MR brake test rig. The results shw that with increase in shear rate, there is decrease in braking trque. Keywrds: MR fluid, MR brake, Shear behavir. 1. Intrductin 1 Magnetrhelgical (MR) suspensins are knwn fr dramatic change in their apparent viscsity. Due t their variable viscsity, MR fluids are used in engineering applicatins requiring cntrllable dynamic perfrmance. One such applicatin is magnetrhelgical brake in which MR fluid is treated as a brake lining material. This material des nt wearaway and prvides desirable frictin resistance by just cntrlling the magnetic field passing thrugh it. As MR brake invlves electrmagnetism and magnetisable frictin material, this system can be named as electrmagnetic brake (Gupta and Hirani, 2011). It is interesting t nte that this brake in ff state cnditin can wrk as bearings (Hirani, 2009, Hirani et al, 2000, Hirani et al, 1999, Hirani et al, 1998, Muzakkir et al, 2011, Hirani, 2005, Hirani et al, 2001, Muzakkir et al, 2013, Hirani 2004, Muzakkir et al, 2015, Hirani, Verma, 2009, Hirani, Suh, 2005, Hirani et al, 2001, Ra et al, 2000, Hirani et al, 2000, Hirani et al, 2002). A typical MR fluid cnsists f vlume percentage f pure-irn (purity > 99%) particles (size: Ø3-10 micrmeters), suspended in a carrier liquid such as mineral il, synthetic il, water r glycl. A variety f prprietary additives t avid gravitatinal settling, t elude wear and t prmte particle suspensin, are added t MR fluids. MR fluids exhibit maximum yield strengths f kpa fr applied magnetic fields f ka/m. MR brake has been studied by varius researchers (Muzakkir and Hirani, 2015, Muzakkir and Hirani, 2015, Muzakkir and Hirani, 2015, Sarkar and *Crrespnding authr: Chiranjit Sarkar Hirani, 2015), (Sarkar and Hirani, 2013), (Sukhwani, et al, 2009), (Sukhwani and Hirani, 2008), (Sukhwani and Hirani, 2008), (Hirani and Manjunatha, 2007), (Sukhwani, et al, 2007), (Sukhwani, et al, 2006), (Gupta and Hirani, 2011). In their research, shear thinning behaviur f MR fluid (theretical mdel and experimental data) was bserved. It appears that nne f the researchers has measured the shear behaviur using magnetrhemeter. Table 1 Varius viscsity shear rate mdels Name Equatin Cmment Frequently used mdel Bingham[1916] fr plastic and viscus materials. It prvides better fit 2 than Bingham but the Cassn[1959] value f parameters depend n the range f shear rate cnsidered. Pwer Law[1921] Herschel- Bulkley [1926] De Kee [1975] k 1104 Internatinal Jurnal f Current Engineering and Technlgy, Vl.5, N.2 (April 2015) n1 Fr shear thinning n<1 and fr thickening fluids n>1. n At high shear rate, it is bserved that fluid having n<1 (i.e. pseud plastic fluid) becmes Newtnian. Cmbinatin f pwer law and Bingham mdel. - e In applicatin such as MR brake, the true behaviur f MR fluid cannt be btained. Therefre in the present study, the shear behavir f MR fluid using magnetrhemeter as well as MR brake test setup has been presented.

2 2. Viscsity-shear rate mdel f MR fluids As per Chen, et al (2014) MR fluid exhibits Newtnian fluid-like behavir in absence f the external magnetic field, and the cnstitutive equatin is given as (1) The rhelgical perfrmance f MR fluid under shearing flwing mdel in presence f the external magnetic field can be described thrugh Herschel- Bulkey mdel n ( H) ( T) (2) Where,τ(H) represents the dynamic yield stress f MR fluid, which varies alng with the strength f the external magnetic field, η(t) represents the viscsity f MR fluid as functin f the perating temperature T, γ represents the shear strain rate f MR fluid, and n is cnstant. There are a number f similar mdels presented in the Literature and the mst widely used mdels (Larsn, 1999) fr viscsity-shear rate relatin are summarized in Table 1.Due t lack f any reliable mdel, expressing shear behaviur f MRF, it is necessary t perfrm experimental study n MRF using magnetrhemeter and setup incrprating MR brake s that the viscsity variatin with shear rate can be mdelled. which is the limitatin f used Magnetrhemeter. It appears that dynamic yield strength increases with increase in shear rate up t 1000 s -1, but there is decrease in yield strength beynd 1000 shear rate. The trend f shear thinning behaviur (frm 0 t 1000 s -1 shear rate) remains same even when magnetic field is changed frm ka/m t ka/m. Hwever, there is reductin (figure 1) in dynamic strength with increase in shear rate at zer magnetic field. T cnfirm the shear thinning behaviur, the dynamic yield stress at different shear rate (up t 1000 s -1 shear rate) ranges have been pltted in Figure 2. It shws that the slpe f the dynamic yield stress vs. shear rate fr different magnetic fields reduces. (a) Frm shear rate 0 t 1.5s -1 (b) Frm shear rate 2 t 40s -1 Figure 1 Shear behavir f MR fluids In the present study, ANTON PAAR mdular cmpact rhemeter MCR-102 has been used t measure the shear stress flw curve f MR fluid (85% by irn particles) at different magnetic fields in cntrlled shear rate (CSR) mde. The measurements were perfrmed in a parallel plate system with a diameter f 20 mm at a gap f 1 mm fr varius input currents (0.1 t 4.8 A). The resulting flw respnses have been examined as a functin f magnetic field strength ranging frm 0 t ka/m. The magnetic field strength (A/m) has been calculated frm the magnetrhelgical cell 70/1T MRD. The perating temperature f 30ºC was maintained. The results f yield strength as functin f shear rate are pltted in Figure 1. The maximum value f shear rate is 3000, (c) Frm shear rate 70 t 1000s -1 Figure 2 Shear behavir fr different range f shear rate T study the shear behaviur f MR fluids, the cmparisn between different available mdels and synthesised MR fluid mdel have been pltted in Figure Internatinal Jurnal f Current Engineering and Technlgy, Vl.5, N.2 (April 2015)

3 Frm this figure it can be cncluded that the MR fluid underges shear thinning behaviur up t 1000 s -1 shear rate, but beynd that it des nt fllw any particular mdel. Therefre, it can be cncluded that a deeper study is required t mdel the shear behaviur f MR fluid. magnetic flux in the gap. Practical gap generally range frm 0.25 t 2 mm. Current in the cil, supplied with 12 VDC, creates magnetic field in the gap. Magnetic field strength depends n the current in the cil. Value f the current can be set frm 0 t 1 A. Viscsity f the fluid influences trque. When the current in the cil is equal t zer, n magnetic field is generated and brake trque equal t minimum M min is exerted n the shaft. The M min is equal t the trque caused by bearing, seal and viscsity f the carrier liquid. When current is the maximum (1A) then magnetic field is created and brake has highest pssible value f the trque M max, that is limited nly by maximum current in the cil I max and the cnstructin f the brake. A heat exchanger was designed and munted n the circumference f the MR brake t analyze temperature effect n the dynamic viscsity f the MR fluid. The uter diameter f 110 mm was kept and the water was used a circulating clant t take away heat frm MR brake. A schematic blck f the experimental set up is shwn in Figure 5. Figure 3 Cmparisn f MR fluids behaviur with ther mdels 3. Analysis f shear behavir n MR Brake T understand the rhelgical behavir f the MR fluid, an experimental study was perfrmed n MR brake. The analysis specially invlves study f braking trque vs. temperature at different magnetic field. Figure 5.Schematic blck f the experimental set up (Sukhwani, et al, 2006) Figure 4 MR brake (Seval, 2002) 3.1. Cnstructin f MR brake 3.2. Experimental set up An experimental apparatus fr evaluating the perfrmance f the MR brake (Lrd Crpratin MRB ) was set up. The schematic blck diagram is shwn in Figure 5. The system is cmpsed f fur main parts: DC mtr (with assciated analg speed regulatr), Trque sensr, MR brake and the Heat Exchanger. Trque sensr is cnnected thrugh a data acquisitin card t a cmputer where values are btained. The number f samples taken fr each reading was 2000 data Prcedure Cnstructin f brake is shwn in Figure 4. It cnsists f rtr fixed t the shaft, which is placed in bearing and can rtate in relatin t husing. Between rtr and husing plate, there is a gap filled with MR fluid. Theretically, a smaller gap will be better because the magnetic flux density in the gap decreases sharply with increasing air gap. In additin, a smaller cnstant gap can easily maintain a unifrm distributin f the A testing prcedure, listed belw, was fllwed (1) Rtate shaft f MR brake at speed f 200 RPM fr 1 min as an initial cnditin, which stirs the MR fluid in the brake t distribute it evenly. Circulate water at partial pening thrugh the nzzle cntrl gap. (2) Supply the required current using the 12 VDC pwer supply surce t prvide the required current fr flux generatin Internatinal Jurnal f Current Engineering and Technlgy, Vl.5, N.2 (April 2015)

4 (3) Cntrl the perating temperature is t the desired level between rm temperature t 70ºC. (4) Measure the trque frm the trque sensr. Repeat all sets f reading at 200 and 600 RPM by keeping the temperature cnstant (i.e. 30 C). While taking reading it is necessary t check the presence f nise present in the reading. The required values are btained by averaging all the pints Results T study the shear behavir f MR fluids, the experiments have been dne n the experimental set up as described in Sarkar and Hirani (2015). Figure 6 shws the histgram f the braking trque at 200 RPM and 600 RPM. The crrespnding shear rates fr 200 RPM and 600 RPM are 1000 s -1 and 3000 s -1. It shws that with increase in RPM, there is a decrease in braking trque. Cnclusins Figure 6 Braking trque at different RPM In this study, perfrmance f a MR fluid brake has been evaluated t investigate its shear behavir f MR fluid. Fllwing cnclusins can be drawn frm this study: 1. With increase in speed there is decrease in braking trque. 2. The dynamic yield strength increases with increase in shear rate up t 1000 s -1, but decrease in yield strength beynd 1000 shear rate. 3. If shear rate is larger than 1000 s -1, the MR fluid des nt fllw any particular mdel. The trend f shear thinning remains same even when magnetic field is changed frm ka/m t ka/m up t 1000 s -1 shear rate. T cnfirm such behavir f MR fluid, cmprehensive study is required. References S. Gupta, H. Hirani, (2011), Optimizatin f magnetrhelgical brake, ASME/STLE 2011 Internatinal Jint Triblgy Cnference, pp H. Hirani, (2009),"Rt cause failure analysis f uter ring fracture f fur rw cylindrical rller bearing", Triblgy Transactins, vl.52, n.2, pp H.Hirani, K.Athre, S.Biswas, (2000), A Hybrid Slutin Scheme fr Perfrmance Evaluatin f Crankshaft Bearings, Trans. ASME, Jurnal f Triblgy, vl. 122, n. 4, pp H.Hirani, K.Athre, S.Biswas, (1999), Dynamic Analysis f Engine Bearings, Internatinal Jurnal f Rtating Machinery, vl. 5, n.4, pp H.Hirani, K.Athre, S.Biswas, (1998), Rapid and Glbally Cnvergent Methd fr Dynamically Laded Jurnal Bearing Design, Prc. IMechE (UK), Jurnal f Engineering Triblgy, vl. 212, pp S.M.Muzakkir, H.Hirani, G.D.Thakre, M.R.Tyagi, (2011), Triblgical Failure Analysis f Jurnal Bearings used in Sugar Mill, Engineering Failure Analysis, vl. 18, n. 8, pp H.Hirani, (2005), Multibjective ptimizatin f jurnal bearing using mass cnserving and genetic algrithms, Prc. Institute Mech. Engineers., Part J, Jurnal f Engineering Triblgy, vl. 219, n. 3, pp H.,Hirani, K.,Athre and S.,Biswas," (2001), Lubricant Shear Thinning Analysis f Engine Jurnal Bearings", STLE, Jurnal f Triblgy Transactin, vl 44, n. 1, pp S.M.Muzakkir, H.Hirani and G.D.Thakre, (2013), Lubricant fr Heavily-Laded Slw Speed Jurnal Bearing, Triblgy Transactins, vl.56, n. 6, pp H Hirani (2004), "Multibjective Optimizatin f a jurnal bearing using the Paret ptimal cncept, Prc. Institute Mech. Engineers., Part J, Jurnal f Engineering Triblgy, vl. 218, n. 4, pp H Hirani, T Ra, K Athre and S Biswas, (1997), Rapid perfrmance evaluatin f jurnal bearings, Triblgy internatinal, vl. 30, n.11, pp H Hirani, K Athre, S Biswas, (1999), Dynamically laded finite length jurnal bearings: analytical methd f slutin. Jurnal f triblgy, vl. 121, n. 4, pp S M Muzakkir, K P Lijesh, H Hirani, and G D Thakre, (2015) Effect f Cylindricity n the Triblgical Perfrmance f Heavily-Laded Slw Speed Jurnal Bearing, Prc. Institute Mech. Engineers., Part J, Jurnal f Engineering Triblgy, 2015, vl 229, n.2, pp K.P.Lijesh, H.Hirani, (2015), Design and Develpment f Halbach Electrmagnet fr Active Magnetic Bearing, Prgress In Electrmagnetics Research C, vl. 56, H Hirani and M Verma, (2009), "Triblgical study f elastmeric bearings f marine shaft system", Triblgy Internatinal, vl. 42, n. 2, pp H Hirani and N P Suh, (2005), "Jurnal Bearing Design using Multibjective Genetic Algrithm and Aximatic Design Appraches", Triblgy Internatinal, vl. 38, n. 5, pp H Hirani, K Athre and S Biswas, (2001),"A Simplified Mass Cnserving Algrithm fr Jurnal Bearing under Dynamic Lads", Internatinal Jurnal f Rtating Machinery, vl. 1, pp T V V L N Ra, H Hirani, K Athre, S Biswas, (2000),"An Analytical Apprach t Evaluate Dynamic Cefficients and Nn-linear Transient Analysis f a Hydrdynamic Jurnal Bearing", STLE Triblgy Transactins, vl. 23, n.1, pp H Hirani, K Athre and S Biswas, (2000), "Transient Trajectry f Jurnal in Hydrdynamic Bearing", Applied Mechanics and Engineering. vl. 5, n 2. H Hirani, K Athre and S Biswas, (2002),"Cmprehensive Design Methdlgy fr Engine Jurnal Bearing", IMechE 1107 Internatinal Jurnal f Current Engineering and Technlgy, Vl.5, N.2 (April 2015)

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