Chem. Engg. Seminar Series : Dr. Vivekanand Dabade

Modeling Magnetoelastic Solids Beyond Joule Magnetostriction

This talk presents ongoing work from the Mechanics of Materials Laboratory in the Department of Aerospace Engineering at the IISc, Bangalore. One of the themes of our research is the design of magneto-elastic materials and structures that can be actuated remotely, and that undergo large deformations under moderate external magnetic fields. We pursue this goal through two complementary strategies.

The first strategy concerns slender ferromagnetic structures. We begin with the Kirchhoff kinetic analogy, which relates the motion of a pendulum to the equilibrium of deformable rods. We use it to study how magnetization affects the deformation of a ferromagnetic rod. The analogy, however, does not address stability. We therefore turn to the corresponding equilibrium equations and perform a stability analysis within a Sturm–Liouville eigenvalue framework. We also present preliminary experimental results on magnetically actuated ferromagnetic rods, obtained with a custom loading device. These are followed by an application-motivated design study of a magnetic colonoscope based on the same concepts. Together, these results offer a systematic route to spatially deforming ferromagnetic rod configurations that can be realized experimentally for a range of applications.

The second strategy uses magneto-active polymers (MAPs), which are intrinsically multiscale materials. At the micro-scale, MAPs consist of a periodic distribution of ferromagnetic inclusions embedded in an elastomeric matrix, while at the macro-scale they behave as an effective ferromagnet capable of large, reversible deformations. We have developed a homogenized model for MAPs. It is built on the underlying physics of micromagnetics and elasticity and not on constitutive laws. The total energy is the sum of elastic and magnetostatic contributions. The magnetostatic part captures two effects: particle–particle interactions and the demagnetization energy associated with the overall specimen shape. Effective elastic moduli follow from appropriate combinations of the constituent moduli. For ellipsoidal specimens, the resulting magnetization and magnetostriction curves show that unit-cell geometry strongly influences the macroscopic response.

Together, these two lines of work provide a unified framework for the design of novel magneto-elastic systems. It also guides the systematic development of new magnetically responsive materials and architectures with controllable deformation.

Bio:

Vivek is an Assistant Professor in the Department of Aerospace Engineering at the Indian Institute of Science (IISc), Bangalore. Prior to joining IISc, he was a Postdoctoral Research Scholar at the Solid Mechanics Laboratory, École Polytechnique, France. He received his Ph.D. in Aerospace Engineering and Mechanics from the University of Minnesota and his Master’s degree in Engineering Mechanics from the Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bangalore. His research interests lie in solid mechanics and applied mathematics.