Instability-Induced Pattern Formations in Soft Magnetoactive Composites

Abstract

Elastic instabilities can trigger dramatic microstructure transformations giving rise to unusual behavior in soft matter.Motivated by this phenomenon, we study instability-induced pattern formations in soft magnetoactive elastomer (MAE) composites deforming in the presence of a magnetic field. We show that identical MAE composites with periodically distributed particles can switch to a variety of new patterns with different periodicity upon developments of instabilities. The newly formed patterns and post-buckling behavior of the MAEs are dictated by the magnitude of the applied magnetic field. We identify the particular levels of magnetic fields that give rise to strictly doubled, or multiplied periodicity upon onset of instabilities in the periodic particulate soft MAE. Thus, the predicted phenomenon can be potentially used for designing new reconfigurable soft materials with tunable material microstructures remotely controlled by magnetic field.

Wrinkling of soft magneto-active plates

“…Note that the magneto-elastic material models (67) and ( 68) take no account of particleparticle interactions and thus neglect magneto-mechanical coupling in terms of pure material magnetostriction. However, it is emphasized that the neo-Hookean magnetization saturation model ( 68) allows for a satisfactory quantitative and very good qualitative agreement with the experimental data presented in previous works (Psarra et al, 2017(Psarra et al, , 2019Goshkoderia et al, 2020), although it is anticipated to be less accurate in the post-bifurcation regime, especially when wrinkles develop substantially due to the large shear strains. As a result, more elaborate magneto-mechanical models such as the ones proposed recently by Mukherjee et al (2020) are required to explore the effects of the strain-stiffening and the constituent phase properties (such as particle volume fraction, particle-particle interactions, etc) on the wrinkling instability of SMA structures, but such models are out of the scope of this paper.…”

“…has been adopted to investigate instability-induced pattern evolutions of the heterogeneous materials and structures (Psarra et al, 2017(Psarra et al, , 2019Goshkoderia et al, 2020).…”

“…Hence Psarra et al (2017Psarra et al ( , 2019) made use of wrinkling and crinkling instabilities of a thin SMA film bonded on a soft non-magnetic substrate to achieve surface pattern control through a combined action of magnetic field and uni-axial pre-compression. Goshkoderia et al (2020) investigated experimentally instability-induced pattern evolutions in SMA elastomer composites driven by an applied magnetic field.…”

The Emergence of Sequential Buckling in Reconfigurable Hexagonal Networks Embedded into Soft Matrix

“…The elastic instabilities were used to adjust the stiffness or auxeticity of structured materials [25,32], open and close elastic bandgaps [33], and realize other unusual wave phenomena [34]. Adding a soft deformable matrix into the design facilitates extra coupling between stiff components, enabling more Materials 2021, 14, 2038 2 of 13 involved buckling behavior accompanied by the formation of various instability-driven patterns [35,36].…”

Ground state of magnetocrystals

“…Using an external field orienting the dipoles, the magnetic particles can be used for bending or stretching these elastic composites creating smart actuators [9,27]. The way particles are arranged in the matrix is relevant for creating different behaviors [28] and instabilities [9].…”