Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99687

99687 - Local Resonance Bandgap Tunability in an Anisotropic Magnetorheological Metamaterial 

Recent advances in the design of active elastic metamaterials has opened up new opportunities in structural mechanics, material design, and energy flow in solids. Of interest is the notion of tuning subwavelength bandgaps, i.e., frequency regions of forbidden wave propagation, in metamaterials with locally resonant mechanisms. The location, strength, and bandwidth of such gaps can be generally altered by geometric reconfiguration of the metamaterial unit cell or via property response to external stimulus, such as an external electric, magnetic, or thermal field which can be effectively tuned in real time. In this work, we present a physical realization of an anisotropic magnetorheological metamaterial and a comprehensive experimental investigation of its performance characteristics under changing magnetic loads. Magneto-mechanical coupling in magnetorheological elastomers (MREs) provides a unique platform to tune the stiffness profile of a locally resonant structure which offers low cost, reversible response, and long lifetime expectancy. While the elastic modulus of a magnetorheological elastomer can be tuned as a function of the applied magnetic field, the vast majority of current literature utilizes isotropic MREs in metamaterial unit cell design. As such, the strength of the induced magneto-mechanical coupling, and hence the tunability of resonant core, is significantly limited due to the uniform distribution of ferromagnetic particles in the elastomeric medium. In the current study, we model, design, and synthesize a finite locally resonant metamaterial with an anisotropic magnetorheological stiffness, and emphasize the effect of such anisotropy on the magneto-mechanical coupling and the level of bandgap tunability. At the fabrication stage, the ferromagnetic particles are aligned with respect to a magnetic field which is applied during the curing process. As a result, particle chains with preferred orientation form along the magnetic field direction, thus notably boosting the mechanical response of the material to magnetic stimulation. To evaluate the effect of magnetic anisotropy and the directional dependence of the material’s magnetic properties on the magneto-mechanical coupling, scanning electron microscopy and energy dispersive X-ray spectroscopy mapping measurements are conducted to understand the anisotropic magnetic behavior in the aligned MRE samples. Following which, we exploit this strong coupling to achieve strong local resonance bandgap control in a magnetically activated metamaterial with a magnetorheological filler. The shift of locally resonant bandgap to higher frequencies as a result of applied magnetic field is demonstrated numerically and verified experimentally using scanning laser Doppler vibrometry, thus setting a roadmap for broader implementations of in situ tunable active metamaterials.

Presenting Author: Mohammadreza Moghaddaszadeh University at Buffalo (SUNY)

Presenting Author Biography: PhD Student<br/>University at Buffalo (SUNY)

Authors:

Mohammadreza Moghaddaszadeh University at Buffalo (SUNY)
Andrew Ragonese University at Buffalo (SUNY)
Yong Hu University at Buffalo (SUNY)
Zipeng Guo University at Buffalo (SUNY)
Amjad Aref University at Buffalo (SUNY)
Chi Zhou University at Buffalo (SUNY)
Shenqiang Ren University at Buffalo (SUNY)
Mostafa Nouh University at Buffalo