Smart Nanocomposites Lab at UC Irvine
Dynamic Mechanical Analysis of Magnetorheological Composites
The characteristics of magnetorheological materials shows promise for their use in wide applications such as high-power magnetostrictive actuation for anti-vibration applications, magnetoelastic sensor application in civil infrastructures monitoring, and smart on-demand damping control. Studies of magneto-mechanical responses for magneto-rheological elastomer composites is recently of great interest to researchers and engineers in many science and engineering disciplines with civil infrastructures in particular. While efforts have been made, the inferior mechanical responses of the soft matrix severely inhibit their wide applications.
To overcome the challenge
mentioned above we develop a novel type of magnetorheological (MR) elastomer
nanocomposites filled with carbon nanotubes. We further conduct an integrated
experimental and modeling approach to investigate the dynamic mechanical
behavior of silicone-rubber-based MR nanocomposites enhanced by multi-walled
carbon nanotubes. First, the novel MR nanocomposites have been fabricated, with
their microstructures and dynamic viscoelastic properties under applied
magnetic fields subsequently characterized via scanning electron microscope and
dynamic mechanical analysis. A micromechanics-based constitutive model is then
proposed to predict the dynamic viscoelastic behavior of multi-phase composites
with viscoelastic imperfect interfaces. With the incorporation of the classic
dipole-dipole magnetic interaction model, the scope of the proposed model has
been extended to cover as well the magnetic-field-induced changes in dynamic
stiffness and damping of MR nanocomposites.
The dynamic mechanical behavior
of the MR nanocomposite and MR elastomer under applied magnetic field has been
characterized at room
temperature, through dynamic single lap-shear test with a dynamic mechanical analyzer.
The zero-field storage modulus G’ and damping ratio tan δ of MR nanocomposite
are at least 30% and 40% higher than those of conventional MR elastomer,
respectively, which proves the effective mechanical reinforcement by only 1 wt%
of MWNTs in the matrix. The absolute MR effect on G’ of MR nanocomposite can reach
up to 0.3 MPa, which is almost 70% higher than that of conventional MR
elastomer, while the relative MR effect on G’ is only around 25% higher since
the zero-field G’ is also increased. It is quite possible that a better bonding
between iron particles and the matrix has been induced by MWNTs, which leads to
the increase in the absolute MR effect. In case of tan δ, the absolute MR
effect remains almost unchanged change while the relative MR effect decreases.
The research conducted is among the first attempt to combine the
advantages of nanocomposites and magnetostrictive materials to produce the
novel MR nanocomposites. The work is expected to lead to advances in the
development of smart nano-composites in applications such as smart valves,
smart wings, adaptive vibration control and noise reduction, and non-contact
1. Li, R. and Sun, L.Z., 2011, “Dynamic mechanical behavior of magnetorheological nanocomposites filled with carbon nanotubes”, Applied Physics Letters, vol. 99, 131912-1-3.
2. Li, R. and Sun, L.Z., 2011, “Dynamic mechanical analysis of silicone rubber reinforced with multi-walled carbon nanotubes”, Interaction and Multiscale Mechanics, vol. 4, 239-245.
3. Wang, H., Zhang, Y.N., Yang, T., Zhang, Z.D., Sun, L.Z., and Wu, R.Q., 2010, “Ab initio studies of the effect of nanoclusters on magnetostriction of Fe1-xGax alloys”, Applied Physics Letters, vol. 97, 262505-1-3.
4. Liu, D.X., Zhang, Z.D., and Sun, L.Z., 2010, “Nonlinear elastic load-displacement relation for spherical indentation on rubberlike materials”, Journal of Materials Research, vol. 25, 2197-2202.
5. Yin, H.M., Sun, L.Z., and Chen, J.S., 2006, “Magnet-elastic modeling of composites containing chain-structured magnetostrictive particles”, Journal of the Mechanics and Physics of Solids, vol. 54, 975-1003.