Effect of Volume Fraction on Shear Mode Properties of Fe-Co and Fe-Ni Filled Magneto-Rheological Elastomers

Abstract

In this research, the synergistic behavior of magnetorheological elastomers containing nickel and cobalt along with iron particles as magnetically polarizable fillers is examined experimentally under dynamic shear loading. Two different types of magnetorheological elastomer were fabricated having equal proportions of iron and nickel in one kind, and iron and cobalt in the other. The concentrations of magnetic particles in each type are varied from 10% to 40% and investigated for several frequencies, displacement amplitude, and magnetic field values. A test assembly with moveable permanent magnets was used to vary magnetic field density. Force displacement hysteresis loops were studied for dynamic response of magnetorheological elastomers (MREs). It was observed that MREs showed a linear behavior at low strains while nonlinearity increased with increasing strain. The percentage filler content and frequency increased the MRE stiffness whereas it decreased with displacement amplitude. The computed maximum magnetorheological (MR) effect was 55.56 percent. While MRE with iron and cobalt gave the highest effective stiffness, MRE with iron and nickel gave the highest MR effect.

Keywords: base isolator; cobalt; high strains; iron; magnetorheological effect; magnetorheological elastomer; nickel; percentage filler content.

Figure 1

Particle size analysis graphs of (a) Iron filler particles (b) Cobalt filler particles (c) Nickel filler particles.

Figure 2

SEM images of (a) Cobalt (b) Nickel and (c) Iron particles.

Figure 3

SEM images for MR Elastomers (a) 40% Ni-Fe (b) 40% Co-Fe (c) 10% Ni-Fe (d) 10% Co-Fe.

Figure 4

EDS graphs for (a) 40% Co-Fe MRE and (b) 40% Ni-Fe MRE samples.

Figure 5

Experimental assembly and set up for dynamic testing (a) magnetic assembly holding magnets and elastomers (b), (d) experimental assembly fixated in the dynamic testing machine (c) Zwick/Roell Servohydraulic testing machine used for dynamic loading.

Figure 6

Comparison of amplitude effect on 40 % filler at maximum and minimum flux (a) 40% Co-Fe at 0.4 T (b) 40% Ni-Fe at 0.4 T (c) 40% Co-Fe at 0 T (d) 40% Ni-Fe at 0 T.

Figure 7

Effect of changing amplitude and flux at maximum filler and maximum frequency on the stiffness of (a) Co-Fe MRE (b) Ni-Fe MRE.

Figure 8

Comparison of amplitude and effective stiffness trends at (a) 40% filler and 0.4 T flux (b) 20% filler and 0.1 T.

Figure 9

Comparison of force-displacement graphs for changing the frequency at maximum and minimum filler content for Ni-Fe MRE in (a,b) and Co-Fe MRE in (c,d).

Figure 10

Comparison of % filler content (10, 20, 30 & 40%) between MRE containing Cobalt and Iron (a,c,e,g) and MRE having Nickel and Iron (b,d,f,h) while simultaneously studying the effect of frequency and magnetic field on effective stiffness.

Figure 10

Comparison of % filler content (10, 20, 30 & 40%) between MRE containing Cobalt and Iron (a,c,e,g) and MRE having Nickel and Iron (b,d,f,h) while simultaneously studying the effect of frequency and magnetic field on effective stiffness.

Figure 11

Effect of frequency and amplitude on effective stiffness at 40% filler content and 0.4 T magnetic field on (a) Ni-Fe MRE and (b) Co-Fe MRE.

Figure 12

Comparison of (a) 30% Co-Fe MRE and (b) 30% Ni-Fe MRE force-displacement graphs with respect to changing flux.

Figure 13

Effect of magnetic field and frequency on effective stiffness of (a) 30% Ni-Fe MRE and (b) 30% Co-Fe MRE.

Figure 14

Effect of flux and displacement amplitude on effective stiffness of (a) 40% Ni-Fe MRE compared with (b) 40% Co-Fe MRE.

Figure 15

MR effect against every percentage of filler content for (a) Ni-Fe MREs and (b) Co-Fe MREs.

Figure 16

Comparison of (a) Maximum MR effect and (b) Maximum stiffness values for different %filler contents.