Critical and post-critical behaviour of two-degree-of-freedom flutter-based generators

Pigolotti, Luca; Mannini, Claudio; Bartoli, Gianni; Thiele, Klaus

doi:10.1016/j.jsv.2017.05.024

Cited by 43 publications

(11 citation statements)

References 56 publications

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“…Thus, the increase in the moment of inertia of the first link has a stabilizing effect. In the same time, increase in the moment of inertia of the second link, as was noted for (14), can result in destabilization of the equilibrium.…”

Section: Stability Of the Trivial Equilibriummentioning

confidence: 69%

“…Here = √ −1 is imaginary unit. From (14) it follows, obviously, that ℜ( 1,2 ) < 0. As for 3,4 , their real parts are negative, if̄is sufficiently large, and positive, if̄is small (that is, if the wing is located close enough to the joint 2 .…”

Section: Stability Of the Trivial Equilibriummentioning

confidence: 99%

“…A flag-flutter based piezoelectric power generator is investigated numerically and experimentally in paper [13]. The energy harvesting performance of a classical-flutter based system is investigated [14] (damping in heave is used to simulate the load in the generator circuit). In [15], a stall flutter of a wing connected with a piezoelectric beam is used to harvest the flow energy.…”

mentioning

confidence: 99%

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Piezoaeroelastic system on the basis of a double aerodynamic pendulum

2020

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During last decades, possibilities to use piezoelectric generators to harvest energy from the flow‐induced vibrations of different structures are intensively studied. In particular, various wind power harvesters based on fluttering oscillations of wing sections are proposed. In this work, an electromechanical system is considered that consists of a double aerodynamic pendulum connected with a piezoelectric element in such a way that rotation of the first link of the pendulum results in deformation of the piezoelement. The element is connected to a load resistance. Stability of the trivial equilibrium is analyzed, and conditions for stability loss are discussed. It is shown, in particular, that it is possible to choose parameters of the system in such a way that the trivial equilibrium (where both links of the pendulum are oriented along the incoming flow) is unstable when the wind speed belongs to a certain finite range of values, and asymptotically stable outside this range. Periodic solutions of the system are studied numerically depending on the wind speed and the moment of inertia of the second pendulum link. The effect of disappearance of limit cycles in the range of large wind speeds is demonstrated.

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Section: Stability Of the Trivial Equilibriummentioning

confidence: 69%

Section: Stability Of the Trivial Equilibriummentioning

confidence: 99%

mentioning

confidence: 99%

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Piezoaeroelastic system on the basis of a double aerodynamic pendulum

2020

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“…It is not our intent to participate in this debate; for the sake of this paper, we consider follower forces as useful abstractions for a variety of physical phenomena and engineering applications. Examples not just include structural mechanics, but cover rotordynamics and gyrodynamics (Samantaray et al, 2008), robotics and automatic control (Kooijman et al, 2011), aeroelasticity (Pigolotti et al, 2017), fluidstructure interactions (Mandre and Mahadevan, 2009), smart materials (Karami and Inman, 2011), biomechanics (Aoi et al, 2013), hydrodynamic peeling (Salussolia et al, 2020), (Rohlmann et al, 2009), cytoskeletal dynamics (Bayly and Dutcher, 2016) and molecular motors (De Canio et al, 2017) and even in astrophysics (Chandrasekhar, 1984) and geophysics (Kirillov, 2017). Follower forces fall under the more general umbrella of circulatory forces (Kirillov, 2013;Shukla, 2015, 2016).…”

Section: Introductionmentioning

confidence: 99%

Extreme deformations of the cantilever Euler Elastica under transverse aerodynamic load

Misseroni

Barbieri

Pugno

2021

Extreme Mechanics Letters

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“…This class of forces includes follower forcesthat is forces always aligned along the centerline of the deforming filament -that move with the filament as it deforms. The primary motivation for studying these came initially from problems in aeroelasticity [26] and flowinduced energy harvesting [27]. Recent focus has however been on problems involving follower forces in bio-inspired systems comprised of soft filaments immersed in a fluidic medium.…”

Section: Introductionmentioning

confidence: 99%

Flapping, swirling and flipping: Non-linear dynamics of pre-stressed active filaments

Fatehiboroujeni¹,

Gopinath

Goyal

2020

Preprint

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Initially straight slender elastic filaments and rods with geometrically constrained ends buckle and form stable two-dimensional shapes when compressed by bringing the ends together. It is known that beyond a critical value of this pre-stress, clamped rods transition to bent, twisted three-dimensional equilibrium shapes. Here, we analyze the three-dimensional instabilities and dynamics of such pre-stressed, initially twisted filaments subject to active follower forces and dissipative fluid drag. We find that degree of boundary constraint and the directionality of active forces determines if oscillatory instabilities can arise. When filaments are clamped at one end and pinned at the other with follower forces directed towards the clamped end, stable planar flapping oscillations result; reversing the directionality of the active forces quenches the instability. When both ends are clamped however, computations reveal a novel secondary instability wherein planar oscillations are destabilized by off-planar perturbations resulting in three-dimensional swirling patterns with periodic flips. These swirl-flip transitions are characterized by two distinct and time-scales. The first corresponds to unidirectional swirling rotation around the end-to-end axis. The second captures the time between flipping events when the direction of swirling reverses. We find that this spatiotemporal dance resembles relaxation oscillations with each cycle initiated by a sudden jump in torsional deformation and then followed by a period of gradual decrease in net torsion until the next cycle of variations. Our work reveals the rich tapestry of spatiotemporal patterns when weakly inertial strongly damped rods are deformed by non-conservative active forces. Practically, our results suggest avenues by which pre-stress, elasticity and activity may be used to design synthetic fluidic elements to pump or mix fluid at macroscopic length scales.

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Critical and post-critical behaviour of two-degree-of-freedom flutter-based generators

Cited by 43 publications

References 56 publications

Piezoaeroelastic system on the basis of a double aerodynamic pendulum

Piezoaeroelastic system on the basis of a double aerodynamic pendulum

Extreme deformations of the cantilever Euler Elastica under transverse aerodynamic load

Flapping, swirling and flipping: Non-linear dynamics of pre-stressed active filaments

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