Smart hexagonal truss systems exhibiting negative compressibility through constrained angle stretching

Grima, Joseph N.; Caruana‐Gauci, Roberto; Wojciechowski, Krzysztof W.; Evans, K.

doi:10.1088/0964-1726/22/8/084015

Cited by 54 publications

(50 citation statements)

References 22 publications

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“…1 it is observed that m ! À1/3, which is consistent with equations given by Grima et al [21] for regular hexagonal lattices with the angles between bars constrained. In this second case the structure's compliance is dominated by the axial springs.…”

Section: Results: 2d Latticessupporting

confidence: 91%

“…In the limit as k s ! 1 the structure will become like the one discussed in reference [21]. The axial deformation dominated structures are stiffened by repulsive nearest neighbor interactions and softened by attractive nearest neighbor interactions, due to the equivalent linearized axial stiffness of magnetic interactions being positive for repulsion and negative for attraction.…”

Section: Results: 2d Latticesmentioning

confidence: 79%

See 1 more Smart Citation

Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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-This paper investigates the equivalent in-plane mechanical properties of one dimensional (1D) and two dimensional (2D), periodic magneto-elastic lattices. A lumped parameter model describes the lattices using magnetic dipole moments in combination with axial and torsional springs. The homogenization procedure is applied to systems linearized about stable configurations, which are identified by minimizing potential energy. Simple algebraic expressions are derived for the properties of 1D structures. Results for 1D lattices show that a variety of stiffness changes are possible through reconfiguration, and that magnetization can either stiffen or soften a structure. Results for 2D hexagonal and re-entrant lattices show that both reconfigurations and magnetization have drastic effects on the mechanical properties of lattice structures. Lattices can be stiffened or softened and the Poisson's ratio can be tuned. Furthermore for certain hexagonal lattices the sign of Poisson's ratio can change by varying the lattice magnetization. In some cases presented, analytical and numerically estimated equivalent properties are validated through numerical simulations that also illustrate the unique characteristics of the investigated configurations.

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Section: Results: 2d Latticessupporting

confidence: 91%

Section: Results: 2d Latticesmentioning

confidence: 79%

Homogenization of 1D and 2D magnetoelastic lattices

Schaeffer

Ruzzene

2015

EPJ Applied Metamaterials

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“…Auxetic foams have some interesting mechanical properties including, synclastic curvature and improved resilience , indentation resistance , shear resistance , fracture toughness , energy dissipation and vibration damping . In certain density regions, auxetic foams and isotropic auxetic continua can also display negative bulk modulus and negative compliance .…”

Section: Introductionmentioning

confidence: 99%

Low‐kinetic energy impact response of auxetic and conventional open‐cell polyurethane foams

Allen

Shepherd

Hewage

et al. 2015

Physica Status Solidi (b)

102

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This paper reports quasi‐static and low‐kinetic energy impact testing of auxetic and conventional open‐cell polyurethane foams. The auxetic foams were fabricated using the established thermo‐mechanical process originally developed by Lakes. Converted foams were subject to compression along each dimension to 85% and 70% of the unconverted dimension during the conversion process, corresponding to linear compression ratios of 0.85 and 0.7, respectively. The 0.7 linear compression ratio foams were confirmed to have a re‐entrant foam cell structure and to be auxetic. Impact tests were performed for kinetic energies up to 4 J using an instrumented drop rig and high speed video. A flat dropper was employed on isolated foams, and a hemispherical‐shaped dropper on foams covered with a rigid polypropylene outer shell layer. The flat dropper tests provide data on the rate dependency of the Poisson's ratio in these foam test specimens. The foam Poisson's ratios were found to be unaffected by the strain rate for the impact energies considered here. Acceleration‐time data are reported along with deformation images from the video footage. The auxetic samples displayed a six times reduction in peak acceleration, showing potential in impact protector devices such as shin or thigh protectors in sports equipment applications.

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“…Due to their counter-intuitive properties, auxetic materials have been investigated as smart materials for potential applications including cushion materials [9], stents [10,11], pressure vessels [12], sensors [13], morphing airfoils [14,15], smart folding structures [16], smart metamaterials [17], aeroengine fan blades [18], and vibration dampers [19], to name a few. Arising from their unique properties, the mechanical performance of auxetic solids has been investigated [20][21][22][23][24][25][26][27][28][29][30][31][32][33], including their elastic stabilities [34][35][36]. Additionally, investigations in the dynamic behavior of auxetic solids and structures have also been performed [37][38][39][40][41][42][43][44][45].…”

Section: Introductionmentioning

confidence: 99%

Buckling and Vibration of Circular Auxetic Plates

Lim

2014

Journal of Engineering Materials and Technology

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This paper evaluates the elastic stability and vibration characteristics of circuiar piates made from auxetic materials. By solving the general solutions for buckling and vibration of circular piates under various boundary conditions, the critical buckling ioad factors and fundamental frequencies of circular plates, within the scope of the first axisymmetric modes, were obtained for the entire range of Poisson's ratio for isotropic solids, i.e., from -1 to 0.5. Results for elastic stability reveal that as the Poisson's ratio of the plate becomes more negative, the criticai bucking ioad gradually reduces. In the case of vibration, the decrease in Poisson's ratio not only decreases the fundamental frequency, but the decrease becomes very rapid as the Poisson's ratio approaches its lower limit. For both buckling and vibration, the plate's Poisson's ratio has no effect if the edge is fully clamped. The results obtained herein suggest that auxetic materials can be employed for attaining static and dynamic properties which are not common in plates made from conventional materials. Based on the exact results, empiricai models were generated for design purposes so that both the critical buckling load factors and the frequency parameters can be conveniently obtained without calculating the Bessel functions.

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Smart hexagonal truss systems exhibiting negative compressibility through constrained angle stretching

Cited by 54 publications

References 22 publications

Homogenization of 1D and 2D magnetoelastic lattices

Homogenization of 1D and 2D magnetoelastic lattices

Low‐kinetic energy impact response of auxetic and conventional open‐cell polyurethane foams

Buckling and Vibration of Circular Auxetic Plates

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