Tunable Acoustic Valley–Hall Edge States in Reconfigurable Phononic Elastic Waveguides

Controlling the flow of mechanical energy in elastic structures has been a long-standing challenge in many areas of engineering, particularly those dealing with vibrations and structure-borne noise. In light of recent studies on the quantum valley Hall effect in electronic systems, the authors show that $a\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}c$ topological edge states can be achieved, at a boundary or interface between two elastic waveguides having broken space-inversion symmetry. The topological properties of such waveguides can be tuned by applying a controlled strain field, while the resulting edge states show a relatively high insensitivity to defects.