Elastic instability

The importance of fluidelastic forces in flow-excited vibrations is crucial, in view of their damaging potential. Flow-coupling coefficients are often experimentally obtained from vibration experiments, performed within a limited experimental frequency range. For any given flow velocity, these coefficients are typically frequency-dependent, as amply documented in the literature since the seminal work of Tanaka and Takahara.

We investigate the fluid-elastic instability of a square tube bundle subject to two-phase cross-flow. A dimensional analysis is carried out, leading to a new criterion of instability. This criterion establishes a direct link with the instability thresholds in single-phase flows. In parallel to the dimensional analysis, experimental work is carried out to i) determine the instability thresholds in single-phase flows (new relation between the Scruton, Stokes and Reynolds number), ii) to test the validity of the two-phase flow instability criterion, derived from the dimensional analysis.

A bistable curved beam with magnetic torque-driven actuation has the potential for fast and untethered reconfiguration of metamaterials. However, no modeling method of a bistable curved beam whose instability is coupled with an external magnetic field for the design of active metamaterials. A bistable curved beam's second mode (S-shape) generation is essential for a multimodal and multistep reconfiguration of metamaterials, which was not explored before.

Journal Club for May 2019: Using Instabilities to Control Soft Robots Philipp Rothemund University of Colorado Boulder

Please find our new publication in Physical Review Letters on Elastocapillar Crease. This paper has been highlighted by Editors Suggestion.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.122.098003

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