Magneto-Active Solids for Adaptive Structures: Can Magnetic Fields Control Elastic Waves?

Magneto-active solids couple their mechanical response to externally applied magnetic fields, providing a promising route toward remotely tunable materials and structures. Such functionality is particularly attractive for aerospace applications involving vibration isolation, adaptive structures, sensing, and elastic-wave control. However, exploiting this coupling requires understanding a fundamental question: when does a magnetic field actually modify elastic-wave propagation, and which wave modes are affected?

In this seminar, Prof. Galich will present recent theoretical and experimental work on elastic waves in magneto-active solids. Starting from the incremental theory of nonlinear magnetoelasticity, he will introduce the generalized acoustic tensor governing small-amplitude waves superimposed on a magnetically biased state. For compressible isotropic magneto-active polymers, magnetic tunability is shown to be strongly dependent on wave polarization. In an undeformed material subjected to a magnetic field transverse to the propagation direction, the shear wave polarized along the magnetic field is directly field-sensitive, whereas the pressure wave and the orthogonally polarized shear wave remain essentially unaffected. These theoretical predictions are supported by ultrasonic experiments on 3D-printed iron-filled polymers.

The discussion will then extend from bulk waves to Rayleigh surface waves, where the coupling between mechanics and magnetism introduces additional questions concerning constitutive modeling and stability. In particular, physically consistent selection of magnetoelastic material parameters is essential: models that reproduce the magnetic permeability but violate the corresponding Maxwell-stress condition can predict artificially strong wave-speed changes and even surface instabilities.

Finally, the seminar will cover periodic magneto-active solids, where magnetic fields, finite deformation, and material architecture can be combined to control elastic-wave dispersion and phononic bandgaps. These results illustrate both the opportunities and fundamental limitations of magnetic-field control of elastic waves and provide guidelines for the development of adaptive materials and structures for vibration manipulation.

Speaker :  Prof. Pavel I. Galich

Prof. Pavel I. Galich has been an Assistant Professor at The Stephen B. Klein Faculty of Aerospace Engineering, Technion, since 2020. He earned his Ph.D. in Aerospace Engineering from the Technion in 2018 and served as a Postdoctoral Research Associate in the Department of Materials Science & NanoEngineering (MSNE) at Rice University from 2018 to 2020.