A novel centresymmetric honeycomb composite structure

Bezazi, Abderrezak; Scarpa, Fabrizio; Remillat, Chrystel D L

doi:10.1016/j.compstruct.2005.09.035

Cited by 126 publications

(86 citation statements)

References 6 publications

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“…In classic centresymmetric honeycomb configurations, the auxetic behaviour is due to the global re-entrant shape -i.e., the internal cell angle is negative, giving the cell the butterfly shape typical of auxetic classical configurations 38 . The presence of kinks close to the intersection of the ribs can however produce a negative Poisson's ratio behavior, even though the unit cell of the foam has a global convex behavior with internal positive angles 39 . Figure 7c shows a multi-reentrant 40 honeycomb configuration, where the geometry is defined by the global cell wall aspect ratio (α = h/l), relative thickness (β = t/l), and the kink aspect ratio (γ = a/l).…”

Section: (A) (B) (C) (D) (E)mentioning

confidence: 99%

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

Boba

Bianchi

McCombe

et al. 2016

ACS Appl. Mater. Interfaces

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We describe a new class of negative Poisson's ratio (NPR) open cell PU-PE foams produced by blocking the shape memory effect in the polymer. Contrary to classical NPR open cell thermoset and thermoplastic foams that return to their auxetic phase after reheating (and therefore limit their use in technological applications), this new class of cellular solids has a permanent negative Poisson's ratio behavior, generated through multiple shape memory (mSM) treatments that lead to a fixity of the topology of the cell foam. The mSM-NPR foams have Poisson's ratio values similar to the auxetic foams prior their return to the conventional phase, but compressive stress-strain curves similar to the ones of conventional foams. The results show that by manipulating the shape memory effect in polymer microstructures it is possible to obtain new classes of materials with unusual deformation mechanisms.2

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Section: (A) (B) (C) (D) (E)mentioning

confidence: 99%

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

Boba

Bianchi

McCombe

et al. 2016

ACS Appl. Mater. Interfaces

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“…Cellular structures are lightweight materials that provide out of plane stiffness through transverse shear, which are widely used in aerospace applications [15,16]. Honeycombs with near zero in plane Poisson's ratio (ZPR) and negative Poisson's ratio (auxetic) are more suitable for complex cylindrical applications than the conventional cores that attain positive internal cell angles [17]. Such conventional honeycombs generate anticlastic curvature (saddle shape) when subject to out of plane bending [18,19].…”

Section: Introductionmentioning

confidence: 99%

Morphing nacelle inlet lip with pneumatic actuators and a flexible nano composite sandwich panel

Özdemir

Scarpa

Craciun

et al. 2015

Smart Mater. Struct.

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We present a hybrid pneumatic/flexible sandwich structure with thermoplastic (TP) nanocomposite skins to enable the morphing of a nacelle inlet lip. The design consists of pneumatic inflatables as actuators and a flexible sandwich panel that morphs under variable pressure combinations to adapt different flight conditions and save fuel. The sandwich panel forms the outer layer of the nacelle inlet lip. It is lightweight, compliant and impact resistant with no discontinuities, and consists of graphene-doped thermoplastic polyurethane (G/TPU) skins that are supported by an aluminium Flex-core honeycomb in the middle, with near zero in-plane Poisson's ratio behaviour. A test rig for a reduced-scale demonstrator was designed and built to test the prototype of morphing nacelle with custom-made pneumatic actuators. The output force and the deflections of the experimental demonstrator are verified with the internal pressures of the actuators varying from 0 to 0.41 MPa. The results show the feasibility and promise of the hybrid inflatable/nanocomposite sandwich panel for morphing nacelle airframes.

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“…Different honeycomb configurations result in different values of the in-plane Poisson's ratio. A variety of honeycomb configurations achieving positive/negative/zero Poisson's ratio have been proposed and investigated with special focus on the in-plane mechanics, flatwise compressive strength and the transverse shear modulus [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. Honeycombs with negative Poisson's ratio (NPR) can likewise be described as auxetic [26][27][28].…”

Section: Introductionmentioning

confidence: 99%

In-plane elasticity of a novel auxetic honeycomb design

Huang

Zhang

Scarpa

et al. 2017

Composites Part B: Engineering

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Abstract: This work presents a novel negative Poisson's ratio honeycomb design composed by two parts (a re-entrant hexagonal component and a thin plate part) that provide separate contributions to the in-plane and out-of-plane mechanical properties. The re-entrant hexagons provide the in-plane negative Poisson's ratio, the in-plane compliance and the out-of-plane compressive strength, while the thin plate part connecting the re-entrant hexagonal section bears the large out-of-plane flexibility. This paper focuses on the in-plane mechanical properties of the auxetic cellular structure. Theoretical models related to the in-plane uniaxial tensile modulus, the shear modulus, and the Poisson's ratios have been built and validated using the finite element techniques. The in-plane behavior of the honeycomb has also been investigated against the geometrical parameters of the unit cell using a parametrical analysis. The theoretical and numerical models illustrate good agreement and show the potential of its application in morphing structures. We also provide a benchmark of the auxetic configuration proposed in this work against negative Poisson's ratio topologies from open literature.

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A novel centresymmetric honeycomb composite structure

Cited by 126 publications

References 6 publications

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials

Morphing nacelle inlet lip with pneumatic actuators and a flexible nano composite sandwich panel

In-plane elasticity of a novel auxetic honeycomb design

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