SEM image (5 × 5 μm2) of an elastomagnetic composite with 32 vol% Ni MPs.
(a) Longitudinal stress (σx ) and (b) transverse strain (ɛy ) vs longitudinal strain (ɛx ) characteristic behaviors for 37 vol% Ni MPs. The reported data represent the average values obtained from reiterated experimental cycles; the error bars are too small to be visible.
Scheme of the experimental set-up for on-line resistance measurements as a function of a controlled longitudinal deformation of the bar shaped elastomagnetic composites.
Average value of ln R vs longitudinal strain (ɛx ) in samples with 37 vol% Ni MPs (○) and 43 vol% Ni MPs (□). The error bars are too small to be visible. The solid lines represent the best fit of Eq. (5) to the experimental data.
(a) Experimental set-up for magneto-piezoresistance measurements in elastomagnetic composites: S - sample; C - sample clamping mechanism; P - thin conductive wire providing electric contact with the resistance meter; M - fixed permanent magnet, parallel and coaxial to a second movable magnet not shown in the image. (b) Configuration of the longitudinal component of the magnetic induction field (Bz ) in the sample region for different distances between the magnets: (1) 120 mm (∂Bz /∂z =− 3 T/m), (2) 78 mm (∂Bz /∂z =− 2 T/m), (3) 68 mm (∂Bz /∂z =− 1.5 T/m), (4) 60 mm (∂Bz /∂z =− 1 T/m).
Magneto-piezoresistance ratio (MPR = [R 0 − R(∂Bz /∂z)]/R 0) as a function of the magnetic induction field gradient (∂Bz /∂z) in samples with: 37 vol% Ni MPs (a) and 43 vol% Ni MPs (b). MPR average values and correspondent errors of reiterated measurements are reported.
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