Pulse Dynamics of Flexural Waves in Transformed Plates

Abstract

Coordinate‐transformation‐inspired optical devices have been mostly examined in the continuous‐wave regime: the performance of an invisibility cloak, which has been demonstrated for monochromatic excitation, is likely to deteriorate for short pulses. Here, pulse dynamics of flexural waves propagating in transformed plates is investigated. A practical realization of a waveshifter and a rotator for flexural waves based on the coordinate transformation method is proposed. Time‐resolved measurements reveal how the waveshifter deviates a short pulse from its initial trajectory, with no reflection at the bend and no spatial and temporal distortion of the pulse. Extending the strategy to cylindrical coordinates, a wave rotator is designed. It is demonstrated experimentally how a pulsed plane wave is twisted inside the rotator, while its wavefront is recovered behind the rotator and the pulse shape is preserved, with no extra time delay. The realization of the dynamical mirage effect is proposed, where an obstacle appears oriented in a deceptive direction.

Elastic metamaterials for guided waves: from fundamentals to applications

“…Moreover, Liu et al [348] experimentally demonstrated source illusion devices for flexural wave manipulation. Although not explicitly mentioned here, there is other notable research progress on the relevant topic [349][350][351][352][353][354][355][356][357][358].…”

Cloaking strategy for Love waves

“…Further experiments by Misseroni et al [12,13] showed the possibility of cloaking flexural vibrations in structured plates. However, control of flexural pulse dynamics remains a further challenge [14,15]. We remark that most of the above literature concerns passive cloaking designs, since it exploits the concept of geometric transformation, in the tracks of what earlier proposed for electromagnetic waves.…”