Transversely isotropic magnetoactive elastomers: theory and experiments
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O R I G I NA L
Alireza Beheshti · Ramin Sedaghati
· Subhash Rakheja
Transversely isotropic magnetoactive elastomers: theory and experiments
Received: 28 May 2020 / Accepted: 4 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The current contribution is concerned with the development of novel constitutive equations for anisotropic magnetoactive elastomers (MAEs). A hyperelastic material model for an incompressible magnetoelastic medium representing transversely isotropic MAEs has been developed to investigate their response behavior in the presence of the applied magnetic field while undergoing finite deformation. Transversely isotropic MAE samples in circular cylindrical geometry with 15% iron particle volume fraction are then fabricated and experimentally tested to measure their permeability and torque–twist response. The experimental results have then been effectively utilized to identify the constant material parameters in the proposed material model. Finally, the accuracy and validity of the proposed constitutive equations are demonstrated through the comparison of the simulation and experimental results. Keywords Magnetoactive elastomer · Transversely isotropy · Constitutive equation · Finite torsion
1 Introduction Magnetoactive elastomers (MAEs) are generally categorized as isotropic and anisotropic MAEs. During the fabrication process, the mixture of the elastomeric medium such as silicon rubber and ferromagnetic iron particles can be cured in the presence or absence of the applied magnetic field which results in anisotropic (transversely isotropic if the applied magnetic field is unidirectional) or isotropic MAEs, respectively. In transversely isotropic MAEs, the iron particles form chain-like structures within the elastomeric medium in direction of the applied magnetic field while in isotropic MAEs iron particles randomly and uniformly dispersed [1–4]. In the direction of the applied magnetic field, anisotropic MAEs have generally shown considerable improvement in their mechanical behavior and MA effects compared with their isotropic counterparts [5]. The size and the volume fraction of iron particles significantly affect the elastic and magnetic properties of MAEs. Particle size with average diameter ranging from 0.1 to 6 µm and also volume fraction in the range of 10–50% are generally used in the fabrication of MAEs [6,7]. Moreover, soft particles made of materials such as iron, cobalt and their oxides [8–11] are used as ferromagnetic particles due to their high magnetic permeability and magnetic saturation, and also zero residual magnetization [9]. Due to the application of MAEs in design of adaptive systems and devices, there are many experimental research studies which address the dynamic behavior and characterization of MAE materials [2,9,11–14]. A. Beheshti · R. Sedaghati (B) · S. Rakheja Department of Mechanical, Industrial and Aerospace Engineering, Concordia University, Montreal, QC H3G 1M8, Canada E-mail: [email protected] A. Beheshti E-mail:
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