Hexachiral truss-core with twisted hemp yarns: Out-of-plane shear properties

HCI meets Material Science

“…Auxetic materials have been synthesised as foams [29,30,204,207], ceramics [126], composites [36,60], crystals [12,79,264] and polymers [3,22,181,192], with re-entrant honeycomb cellular structures being the most extensively researched to date [149,206,208,261]. The hexagonal lattice shown in Figure 1 is perhaps the simplest form of an auxetic cellular arrangement, however, other tessellating geometries, such as chiral [2] and rotating unit [78,90], are also capable of creating an auxetic shape-changing mechanism.…”

“…Typically, auxetic structures are anisotropic (i.e. different properties in different directions), undergoing different expansion rates depending on the axis stretched, however, this deformation is Stretchable Structures [6], [27], [32], [44], [46], [98], [111], [112], [141], [142], [151], [174], [175], [174], [176], [197], [212], [213], [216], [221], [223], [242], [246] iSkin [247], Stretchis [248], [128] [2], [3], [12], [22], [29], [30], [36], [57], [58], [59], [60], [78], [118], [149], [153], [181], [192], [201], [203], [204], [205], [206], [207], …”

Composite chiral shear vibration damper

“…Chiral structures with six, four or three-ligaments tessellations are produced by using cylindrical units connected by tangential segments, and the rotation of these units under uniaxial loading leads to the bending and unwinding of the ligaments, with a consequent global volumetric increase of the solid when the loading is tensile. 1 Chiral structures configurations have shown a significant potential for morphing wing and deployable applications [26][27][28], platforms for phononics, wave propagation and smart sensing [29][30][31] and truss-core with increased shear stiffness and strength [32]. The peculiar shear deformation characteristics of the chiral configuration is exploited here to increase the equivalent loss factor associated to modes dominated by shear deformation, like edgewise modal shapes of wind turbine blades with high tensile/compressive stresses at the trailing edge.…”

Fatigue behavior of wood-fiber-based tri-axial engineered sandwich composite panels (ESCP)

“…Gan et al (2004) found that iso-grid structures have good damage tolerance where most of the energy absorption occurs beyond the initial failure. Cicala et al (2012) investigated a truss-core structure made of hemp/epoxy biocomposite by tensile and flexural tests and found that this core exhibits better specific shear modulus and strength than a model made of polymeric core. Zuhri et al (2014) focused on structural materials with either interlocked grid-core made of co-mingled flax-fiber reinforced polypropylene or polylactide polymers.…”