Tunable phononic crystals via instability-induced interfacial wrinkling

We present a method to control wave propagation in highly deformable layered media by utilizing elastic insta-bility-induced wrinkling of interfacial layers. The onset of a wrinkling instability in initially straight interfacial layersoccurs when a critical compressive strain or stress is achieved [1]. Further compression beyond the critical strainleads to an increase in the wrinkle amplitude of the interfacial layer. This, in turn, gives rise to the formationof a system of periodic scatterers, which refl ect and interfere with wave propagation. We demonstrate that thetopology of wrinkling interfacial layers can be controlled by deformation and used to produce band-gaps in wavepropagation and, hence, to selectively fi lter frequencies [2]. Remarkably, the mechanism of frequency fi ltering iseffective even for composites with similar or identical densities, such as polymer–polymer composites. Becausethe microstructure change is reversible, the mechanism can be used for tuning and controlling wave propagationby deformation. REFERENCES[1] Li, Y., Kaynia, N., Rudykh, S., Boyce, M.C. Wrinkling of interfacial layers in stratifi ed composites. Advanced EngineeringMaterials. 2013, 15(10), 921–926.[2] Rudykh, S., Boyce, M.C. Transforming wave propagation in layered media via instability-induced interfacial wrinkling.Physical Review Letters. 2014, 112, 034301.