Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering
Session: 2
Room: Exhibit Hall A
Brynne Skoropys - University of Arizona
Co-Author(s): Miya Coimbra, University of California, San Diego, La Jolla, CA Advisors: Nicholas Boechler, University of California, San Diego, La Jolla, CA; Florian Allein, University of California, San Diego, La Jolla, CA
Topologically protected waves are localized on the edge of a material, propagate only in one direction, and are immune to backscattering. We sought to achieve a system that allows topologically protected edge wave propagation through purely geometric means. In order to obtain this topologically protected state we have constrained our model?s shear, bending, and torsional stiffnesses such that the sum of the bending and torsional stiffnesses equals the bending stiffness; a constraint that has been theorized to enable such a state. To do this, we developed a model of a topological insulator based on a ball-and-stick model which oscillates in a 2D plane. The equations for our stiffness coefficients were derived from fixed-free beam bending principles in solid mechanics, and with these equations we obtained equations of motion for our system. The equations of motion we derived were analyzed in MATLAB to solve for corresponding eigenfrequencies. Finite element analysis using COMSOL simulation software verified the frequencies that resulted in shearing, bending, and torsional motions. We 3-D printed our model in ABS and tested it using a high-speed camera and a shaker, exciting the system at various frequencies. We tracked the displacements of the particles to see if our experimental and theoretical eigenfrequencies were in good agreement. The final system we hope to develop and test is a lattice of graphene-like structure. Future work may include studying the effects of nonlinear stiffnesses on the system. Ultimately, this work may lend to a broader understanding of topologically nontrivial acoustic systems.
Funder Acknowledgement(s): This work was supported by an REU supplement to NSF grant no. EFMA-1640860.
Faculty Advisor: Nicholas Boechler, nboechler@ucsd.edu
Role: Contributed equally to the design and testing of a topologically protected system.