Design, Fabrication, and Characterization of Mechanical Metamaterials

Researchers: Joshua Morris, Weidi Wang, Darshil Shah, Eric Viscione, Alireza Amirkhizi, Christopher HansenĀ 

Sponsors/Collaborators: Army Research Laboratory (ARL)

Description: Frequency dependent mechanical metamaterials have a microstructure consisting of a rigid outer shell and a mass-spring resonant inclusion. The resonance is tuned to produce a wide frequency stop band within which energy transmission through the material is greatly attenuated. Cell arrays are designed using FEM, reduced order models, and algorithm assisted processes. The physics governing energy transfer through the material with realistic boundary conditions is studied, including: dispersion, interface losses, and effects from limited sample dimensions. Samples are fabricated using DLP or sintered 3D printers. Expansion of the design space is being explored using multiple printed materials or geometric variation though the sample thickness. Characterization of samples is performed with an in-house transmission fixture, consisting of: a transducer, semiconductor strain gauges, and frequency generation/measuring electronics. Metamaterials like these have applications for lenses, pressure/blast attenuation, passive vibration filtering, and sound proofing.