<p>Multi-stable lattices of elastomeric beams are a productive construct for the design of mechanical metamaterials.&nbsp; The reversibility of the elastomeric beam buckling has been leveraged in several previous studies to demonstrate novel energy trapping, multi-resonant vibration isolation, and multi-bandgap control of elastic waves. In this work, we extend the library of beam designs that can be utilized in this framework, by investigating the role of beam geometry and material property grading on the buckling and stability of elastomeric beams. Specifically, we use the stiffness programming capacity of liquid crystal elastomers (LCEs) as a model system for tuning mechanical stability of the beams. LCEs are a novel class of polymer networks with tunable, anisotropic mechanical properties that can be programmed through applied strain. Integrating LCEs into a network of elastomeric beams adds geometric nonlinearity into the stiffness programming hierarchy, further broadening the design space and tunability of the beam behavior. However, the confluence of nonlinearities between the mapping of geometry and local strain, and the mapping between local strain and stiffness programming, presents a large and complex design space to navigate. Using a Fourier series parameterization of the beam geometry, combined with 2D plane strain finite element analysis, we compare the evolution of the force displacement curve of beam buckling due to altered cross-sectional geometry.&nbsp; Then, using the strain field of a target post-buckling deformation state, modify the stiffness of the beam based on the local strain information.&nbsp; The study demonstrates an approach to realize the complex stiffness distribution using bending-based deformation modes and provides guidelines on how the strain-programmable stiffness can regulate the stability of the beam. &nbsp;</p>

Tunable Stability of Elastomeric Beams With Strain-Programmable Stiffness

Paper Proceedings: https://asmedigitalcollection.asme.org/IDETC-CIE/IDETC-CIE2021/volume/85369

ASME 2021 International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE2021)

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