Single member actuation of kagome lattice structures

Leung, Anthony; Guest, Simon D.

doi:10.2140/jomms.2007.2.303

Cited by 10 publications

(5 citation statements)

References 11 publications

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“…As we have E = 0 for rigid motions, there is no need for supplementary computations for the energy. We get the same uninteresting result for many structures (like, for instance, the Kagome (trihexagonal) lattice studied in [Leung and Guest 2007]). From now on, we will focus only on structures which have more degrees of mobility.…”

Section: Membranessupporting

confidence: 71%

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2018

Math. Mech. Compl. Sys.

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Section: Membranessupporting

confidence: 71%

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2018

Math. Mech. Compl. Sys.

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“…This approach is not suitable for generating travelling waves efficiently and instead the same effects were achieved in a novel way using a compliant structure based on the kagome lattice geometry. The kagome lattice has long been identified as a structure with unique structural properties which lends itself to this application – the production of in-plane travelling waves [ 26 , 27 ]. When a single member of the lattice is extended, indicated as a dashed line in Fig.…”

Section: Experimental Methodsmentioning

confidence: 99%

Experimental Control of Turbulent Boundary Layers with In-plane Travelling Waves

Bird

Santer

Morrison

2018

Flow Turbulence Combust

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The experimental control of turbulent boundary layers using streamwise travelling waves of spanwise wall velocity, produced using a novel active surface, is outlined in this paper. The innovative surface comprises a pneumatically actuated compliant structure based on the kagome lattice geometry, supporting a pre-tensioned membrane skin. Careful design of the structure enables waves of variable length and speed to be produced in the flat surface in a robust and repeatable way, at frequencies and amplitudes known to have a favourable influence on the boundary layer. Two surfaces were developed, a preliminary module extending 152 mm in the streamwise direction, and a longer one with a fetch of 2.9 m so that the boundary layer can adjust to the new surface condition imposed by the forcing. With a shorter, 1.5 m portion of the surface actuated, generating an upstream-travelling wave, a drag reduction of 21.5% was recorded in the boundary layer with Reτ = 1125. At the same flow conditions, a downstream-travelling produced a much smaller drag reduction of 2.6%, agreeing with the observed trends in current simulations. The drag reduction was determined with constant temperature hot-wire measurements of the mean velocity gradient in the viscous sublayer, while simultaneous laser Doppler vibrometer measurements of the surface recorded the wall motion. Despite the mechanics of the dynamic surface resulting in some out-of-plane motion (which is small in comparison to the in-plane streamwise movement), the positive drag reduction results are encouraging for future investigations at higher Reynolds numbers.

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“…4 Shape-morphing and inelastic networks of slender beams and ribbons Numerous shape-changing mechanisms have been exploited in recent years for the design of active and reconfigurable structures, including single-member actuation [36,37], selective or cooperative buckling [38,39,40,41,12] and activation of natural curvature or axial eigenstrains [42,43,44,4,12]. In practice, such mechanisms can be actuated by purely mechanical devices [39,40,41] as well as by multiphysics coupling such as, e.g., thermo-mechanical effects, photo-elasticity, and electro-mechanical coupling [42,43,44,4,12].…”

Section: Validation Examplesmentioning

confidence: 99%

Modeling of Flexible Beam Networks and Morphing Structures by Geometrically Exact Discrete Beams

Lestringant

Kochmann

2020

Journal of Applied Mechanics

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We demonstrate how a geometrically exact formulation of discrete slender beams can be generalized for the efficient simulation of complex networks of flexible beams by introducing rigid connections through special junction elements. The numerical framework, which is based on discrete differential geometry of framed curves in a time-discrete setting for time- and history-dependent constitutive models, is applicable to elastic and inelastic beams undergoing large rotations with and without natural curvature and actuation. Especially, the latter two aspects make our approach a versatile and efficient alternative to higher-dimensional finite element techniques frequently used, e.g., for the simulation of active, shape-morphing, and reconfigurable structures, as demonstrated by a suite of examples.

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Single member actuation of kagome lattice structures

Cited by 10 publications

References 11 publications

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Experimental Control of Turbulent Boundary Layers with In-plane Travelling Waves

Modeling of Flexible Beam Networks and Morphing Structures by Geometrically Exact Discrete Beams

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