Viscoelastic effects on the overall responses of Terfenol-D/polymer composites

When polymers combine with Terfenol-D constituents, the resulting composites inherently exhibit time-dependent and magnetoelastic coupling behaviors. Herein, we present a mathematical framework to simulate the effective viscoelastic behaviors of Terfenol-D/polymer composites via an incremental micromechanics analysis that is based on the homogenization technique for periodic composites in conjunction with a time-integration technique that enables the use of a recursive algorithm for fast and easy solution of the convolution integral constitutive law for linear viscoelastic polymers. The representation of the monolithic Terfenol-D material is based on a recently developed nonlinear constitutive equation. The resulting composite constitutive relation that governs the time-dependent behaviors of composites are first verified by experimental data existing in literatures and then implemented to study the viscoelastic responses of a polymeric matrix with embedded Terfenol-D particles, continuous fibers and layers, respectively. The hysteresis loops in magnetostriction and magnetic flux density responses as well as in ΔE-effect of this composite due to cyclic magnetic loadings together with prestresses and environmental temperatures are shown. We find that even though the Terfenol-D does not show viscoelastic behaviors, an overall time-dependent magnetoelastic coupling responses of this composite still occurs, arising from viscoelastic effects in the polymer.