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. 2020 Jul 30;13(15):3378.
doi: 10.3390/ma13153378.

Tunable Young's Moduli of Soft Composites Fabricated from Magnetorheological Materials Containing Microsized Iron Particles

Ji-Young Yoon  1 , Seong-Woo Hong  1 , Yu-Jin Park  1 , Seong-Hwan Kim  1 , Gi-Woo Kim  1 , Seung-Bok Choi  1
Affiliations

Tunable Young's Moduli of Soft Composites Fabricated from Magnetorheological Materials Containing Microsized Iron Particles

Ji-Young Yoon et al. Materials (Basel). .

Abstract

This study experimentally investigates the field-dependent Young's moduli of soft composites, which are fabricated from two different magnetic-responsive materials; magnetorheological elastomer (MRE) and magnetorheological fluid (MRF). Four factors are selected as the main factors affecting Young's modulus of soft composites: the amount of MRF, the channel pattern, shore hardness and carbonyl iron particle (CIP) concentration of the MRE layer. Five specimens are manufactured to meet the investigation of four factors. Prior to testing, the scanning electron microscopy (SEM) image is taken to check the uniform dispersion of the carbonyl iron particle (CIP) concentration of the MRE layer, and a magnetic circuit is constructed to generate the effective magnetic field to the specimen fixed at the universal tensile test machine. The force-displacement curve is directly measured from the machine and converted to the stress-strain relationship. Thereafter, the Young's modulus is determined from this curve by performing linear regression analysis with respect to the considered factors. The tunability of the Young's moduli of the specimens is calculated based on the experimental results in terms of two performance indicators: the relative percentage difference of Young's modulus according to the magnetic field, and the normalized index independent of the zero-field modulus. In the case of the relative percentage difference, the specimens without MRF are the smallest, and the ones with the highest CIP concentration are the largest. As a result of comparing the normalized index of each factor, the change in shore hardness and channel pattern have little effect on the tunability of Young's moduli, and the amount of MRF injected and CIP concentration of MRE have a large effect. The results of this study are expected to provide basic guidelines for fabricating soft composites whose field-dependent Young's moduli can be tuned by several factors with different effects.

Keywords: equivalent Young’s modulus; magnetorheological elastomer; magnetorheological fluid; skin layer; soft composite; tensile test.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Various applications of soft composites fabricated from magnetic-responsive materials.
Figure 2
Figure 2
Schematic configuration of the soft composites fabricated from magnetorheological elastomer (MRE) layers and magnetorheological fluid (MRF).
Figure 3
Figure 3
Procedures for fabricating the upper and lower MRE layers: (a) photos of mold; (b) fabrication phases.
Figure 4
Figure 4
Scanning electron microscopy (SEM) images of the MRE layer: (a) with different magnifications and (b) uniform distribution of carbonyl iron particle (CIP).
Figure 5
Figure 5
Pictures of the manufactured soft composites: (a) rectangular pattern, (b) rhombus pattern, and (c) bent shape.
Figure 6
Figure 6
Magnetic-responsive microsized CIP steps of the soft composites: (a) SEM procedure and (b) magnetized sample and SEM image.
Figure 7
Figure 7
Tensile testing machine with the magnetic core structure.
Figure 8
Figure 8
Intra-specimen repeatability test results of five samples (rectangular) under the same conditions.
Figure 9
Figure 9
Effect of the shore hardness of the MRE layers on Young’s modulus.
Figure 10
Figure 10
Effect of the channel pattern of the lower MRE layer on Young’s modulus.
Figure 11
Figure 11
Effect of the CIP concentration of the MRE layers on Young’s modulus.
Figure 12
Figure 12
Effect of MRF contained in the channels of the lower MRE layer on Young’s modulus.
Figure 13
Figure 13
Radar chart of each parameter.
See this image and copyright information in PMC

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