Magnetorheological behavior of isotropic silicone rubber-based magnetorheological elastomers under coupled static–dynamic compressive loads

Abstract

The primary goal of this work is to test and model the magnetorheological (MR) properties of the isotropic magnetorheological elastomers (MREs) under the coupled static–dynamic compressive loads. Isotropic MREs with different contents of magnetic particles were fabricated based on the silicone elastomer. In order to apply the controllable magnetic field to the MREs and directly measure the viscoelastic force of the deformed MREs during the dynamic tests, an electromagnet with a magnetic flux density of up to 0.9 T was developed and integrated into an electric dynamic test system. The stress–strain hysteresis loops of the produced MREs were experimentally characterized under the dynamic compressive loads coupled with different static pre-strains. Effects of particle content, strain amplitude, static pre-strain and load frequency on the MR properties of the MREs were examined in terms of the characteristics of the hysteresis loops, as well as the MR effects in the storage modulus, loss modulus and pre-stress. The results revealed that irrespective of the applied magnetic field, the deformation behavior of the produced MREs was in an approximate linear viscoelastic state when the strain amplitude was less than 7.5%. Both the absolute and relative MR effects increase with the increasing particle content, and decrease with the increasing strain amplitude. Only the absolute MR effect increases with the increasing pre-strain. While varying the load frequency has almost no effect on the MR effect of the MREs. Furthermore, two empirical models were proposed respectively for predicting the storage modulus and loss modulus of the MREs as functions of the magnetic flux density, particle content, strain amplitude, pre-strain and load frequency. The graphical comparison and quantitative evaluation show that the proposed models can give effective predictions of the storage and loss moduli of the produced MREs under the applied load conditions in this work.

Effect of Fumed Silica Nanoparticles on the Performance of Magnetically Active Inks and DIW Printing

“…Soft magnetic particles show low remanence after magnetization, while hard magnetic particles can maintain high remanence intensity after magnetization by a magnetic field. On the basis of their physical properties, polymer matrices can be classified as liquid (e.g., magnetorheological fluids), soft (e.g., hydrogels and silicone rubbers), , and rigid polymers (e.g., thermoplastics) . Therefore, the magnetically active polymers obtained by choosing different combinations of magnetic particles and polymer matrices can also exhibit different properties.…”

A unified understanding of magnetorheological elastomers for rapid and extreme stiffness tuning

“…3b shows the maximum measured MR enhancement factor as a function of E c,B=0 for the materials tested in this work as well as literature data. 17,24,42,56,57 Here, we focus only on the maximum achievable stiffness tuning effect to understand the factors governing the creation of extreme stiffness tuning MREs. We find that eqn (1) accurately predicts the stiffness tuning effect of not only the MREs in this work, but of those reported in previous research as well by fitting the data to a single value of E mag .…”

“…This HC MRE composite gripper is enabling for areas such as robotic 1)). 17,24,42,56,57 manipulation and manufacturing which may require diverse grasping capabilities.…”

“…[35][36][37][38][39] A key feature that has lead to substantial research of MREs is their magnetorheological effect, which leads to magnetic field-driven tunable stiffness, 17,18 variable energy dissipation and damping, 40,41 and shape-memory effects. 42 To improve the stiffness tuning effect (often called the MR effect or MR ratio) of these materials, MREs have been created with varied parameters such as elastomer matrix material, [43][44][45][46][47][48][49][50] magnetic particle size, 28,43,48,51 shape, [52][53][54] and volume fraction, 44,[55][56][57] and recently through the introduction of magnetic fluids as functional content. 29,42,58 Magnetorheological fluids, which are magnetic fluids that rapidly change viscosity and yield stress when subjected to a magnetic field, 59,60 have recently been used as inclusions for MREs.…”

4D printing of hard magnetic soft materials based on NdFeB particles

“…polydimethylsiloxane, hydrogels, silicone rubber, etc.) (Falahati et al, 2020; Zhang et al, 2022) by programing the magnetization of hard magnetic particles combined with the excellent elasticity of soft matrices to achieve heterogeneous magnetization distribution. HASM achieves reversible shape transformation and controlled motion by programing the magnetization of hard magnetic particles with large hysteresis, that is, high remanence and high coercivity (Abbott et al, 2020).…”