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In this paper, we investigate small amplitude oscillations of a thin shape-morphing plate submerged in a quiescent, Newtonian, incompressible, viscous fluid in the vicinity of a solid wall. The plate undergoes prescribed, time-varying shape-morphing deformation in phase with the transverse oscillation, consisting of periodic curvature to an arc of a circle. As the presence of the solid wall in close proximity of the oscillating plate is known to significantly increase hydrodynamic damping on the structure due to squeeze film effects, shape-morphing is considered as a potential strategy to modulate and control hydrodynamic forces, as well as power dissipation. Via a rigorous formulation based on unsteady Stokes equations and the boundary element method, we show that the shape-morphing strategy is effective in reducing hydrodynamic forces on the structure as well as hydrodynamic power dissipation due to viscous effects. Additionally, such a reduction is enhanced as the gap between the oscillating plate and the solid wall is reduced. We present a comprehensive parametric study which investigates the effect of oscillation frequency, gap size, and imposed curvature on the hydrodynamic performance of the system and support our findings with asymptotics from inviscid flow theory and lubrication theory. These findings are of direct interest and applicability in several cantilever-based sensing and actuation systems, such as atomic force microscopy and microelectromechanical systems in liquids. [ABSTRACT FROM AUTHOR]

A novel contact resonance atomic force microscopy (CR-AFM) method utilizing a two-dimensional Kirchhoff-Love plate framework is presented. Theoretical formulations are discussed, and the classic CR-AFM problem is re-cast into an easily implementable generalized eigenvalue problem. An analysis is performed to determine the optimal placement of the sensing tip for plates of different aspect ratios. Finally, an experiment is conducted using the finite element method to numerically verify the proposed technique. By using a plate geometry for CR-AFM and optimizing the sensor tip location, we achieve a higher measurement sensitivity and modal density when compared with standard AFM cantilever geometries. A higher modal density allows CR-AFM measurement to be conducted using more information extracting eigenmodes in a given frequency bandwidth. [ABSTRACT FROM AUTHOR]

In this paper, we study torsional oscillations of a cross section of a thin plate submerged in a quiescent, Newtonian, incompressible, and viscous fluid. The plate is subjected to a prescribed shape-morphing deformation in phase with the rigid oscillation. The problem is completely described by three nondimensional parameters indicating oscillation frequency and amplitude and intensity of the shape-morphing deformation. We conduct a parametric study to investigate the possibility of controlling hydrodynamic moments and power dissipation through an active time-varying shape-morphing strategy. The problem is studied in both the linear and nonlinear flow regimes, by employing the boundary element method and direct numerical simulations via computational fluid dynamics methods, respectively. Investigation of flow physics demonstrates that, similarly to what is observed for the case of flexural oscillations, the shape-morphing strategy is effective in modulating vortex shedding in torsional oscillations. The results show that hydrodynamic power dissipation can be minimized and hydrodynamic moments can be controlled through an optimal imposed shape-morphing deformation. Findings from this study are directly applicable to torsional oscillation-based underwater energy harvesting or sensing and actuation systems, where control of hydrodynamic moments and reduction of hydrodynamic power losses are necessary for optimal device operation. [ABSTRACT FROM AUTHOR]

In this paper, we present a comprehensive experimental study on harmonic oscillations of a submerged rigid plate in a quiescent, incompressible, Newtonian, viscous fluid. The fluid-structure interaction problem is analyzed from both qualitative and quantitative perspectives via a detailed particle image velocimetry (PIV) experimental campaign conducted over a broad range of oscillation frequency and amplitude parameters. Our primary goal is to identify the effect of the oscillation characteristics on the mechanisms of fluid-structure interaction and on the dynamics of vortex shedding and convection and to elucidate the behavior of hydrodynamic forces on the oscillating structure. Towards this goal, we study the flow in terms of qualitative aspects of its pathlines, vortex shedding, and symmetry breaking phenomena and identify distinct hydrodynamic regimes in the vicinity of the oscillating structure. Based on these experimental observations, we produce a novel phase diagram detailing the occurrence of distinct hydrodynamic regimes as a function of relevant governing nondimensional parameters. We further study the hydrodynamic forces associated with each regime using both PIV and direct force measurement via a load cell. Our quantitative results on experimental estimation of hydrodynamic forces show good agreement against predictions from the literature, where numerical and semi-analytical models are available. The findings and observations in this work shed light on the relationship between flow physics, vortex shedding, and convection mechanisms and the hydrodynamic forces acting on a rigid oscillating plate and, as such, have relevance to various engineering applications, including energy harvesting devices, biomimetic robotic system, and micro-mechanical sensors and actuators. [ABSTRACT FROM AUTHOR]