Dynamic Magneto-Mechanical Analysis of Isotropic and Anisotropic Magneto-Active Elastomers

The article investigates the dynamic magneto-mechanical properties of magneto-active elastomers (MAEs), which are soft materials containing magnetic inclusions. It focuses on the magneto-responsive mechanical properties, such as the magneto-rheological effect, which involves a magnetically-induced change in stiffness. The study highlights the superior magnetostrictive properties of anisotropic MAEs due to the close spacing of particles in chains. The research addresses the limitations in existing studies, such as the range of loading conditions and material configurations tested, and the frequency range of testing equipment. The authors designed a custom apparatus for dynamic magneto-mechanical analysis (DMMA) to overcome these limitations and measure the magnetically-induced change in complex moduli under various conditions. The study compares the magneto-mechanical response of isotropic and anisotropic MAEs, including the effects of particle content, frequency, and strain amplitude. The results show that anisotropic MAEs exhibit a larger magneto-rheological effect than isotropic MAEs, with the longitudinal modulus showing the largest absolute change. The study also examines the magnetically-induced change in the loss factor, which indicates the degree of energy dissipation. The findings suggest that both dissipative and non-dissipative mechanisms contribute to the magnetically-induced change in complex modulus. The article concludes by highlighting the potential applications of MAEs in tunable architected materials and the need for further research to develop a complete material model for analysis of such structures.