Fabrication of a short carbon fiber/gel composite that responds to a magnetic field

Abstract

A short carbon fiber (CF)/agarose gel composite in which short CFs were radially embedded in the gel matrix was fabricated. The composite was subjected to strong magnetic fields up to 8 T, to observe its deformation. The composite deformed so that the carbon fibers were aligned parallel to the magnetic field. The deformation was analyzed quantitatively in terms of the magnetic and elastic energies of the composite.

Fabrication and characterisation of short fibre reinforced elastomer composites for bending and twisting magnetic actuation

“…(10) give a value of χ a = 2.20 × 10 −3 . It should be noted that this value is about thirty times larger than the one reported in the literature for neat carbon fibres [16] and is likely due to the nickel functionalisation of the fibres, which make them easier to orient in low magnetic fields.…”

“…The other parameters in (3) are χ = χ a ν f /(2µ 0 ) where χ a represents the magnetic anisotropic susceptibility, µ 0 the vacuum permittivity and ν f is the volume fraction of the fibres [16]. EI and GJ are the bending and twisting rigidities, respectively.…”

“…And in fact, the high responsiveness, large strain capabilities and viscoelastic behaviour of elastomers [34] mean they are ideal materials for such responsive devices [21,20]. Kimura et al [16] produced a carbon fibre/agarose gel composite in which carbon fibres were radially embedded in the gel; by subjecting the sample to a strong homogeneous magnetic field (up to 8 T), large deformations were observed. A similar technique was applied in [17] to produce a silicon rubber-steel wire composite which was actuated with much lower field intensities (≈ 0.2 T).…”

Magnetic alignment of short carbon fibres in curing composites

“…The case of a matrix with constant viscosity is encompassed by the model (10) when γ → 0, a case which was already dealt with in [13] and [14]. The solution of Eq.…”

“…Typically the focus involves the use of fibres dispersed into a liquid solution and oriented by homogeneous fields [13,12,16] as this results in a homogeneous dispersion of fibres (in this case: torque is applied to rotate the fibre, but no translation of the fibre takes place). However, an understanding of the effects of the changing viscosity during the curing phase would be beneficial to have an accurate estimate of the final distribution that can be achieved within the composite and select the optimal configuration in terms of matrix/fibre.…”