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Shear Stiffness and Energy Absorption of Auxetic Open Cell Foams as Sandwich Cores
Author(s) -
Cheng Hong Chun,
Scarpa Fabrizio,
Panzera Tulio Hallak,
Farrow Ian,
Peng HuaXin
Publication year - 2019
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201800411
Subject(s) - auxetics , materials science , composite material , shear (geology) , shear modulus , stiffness , sandwich structured composite , indentation , bending stiffness , core (optical fiber)
This work describes the identification of the shear modulus of open cell polyurethane thermoformed auxetic foams from 3‐ and 4‐point bending tests. The foams are incorporated in sandwich beams with carbon fibre/epoxy face skins, and benchmarked against similar sandwich structures made with the conventional counterpart open cell foam. Three types of beams are tested: one with auxetic foams, another type related to a conventional foam core with the same thickness of the auxetic porous materials, and a third type of beam consisting in conventional foam with a thickness corresponding to an iso‐weight configuration to the auxetic specimen. The auxetic foam has a shear modulus 7% lower than the one of the bulk conventional specimens, but higher shear stresses at large deformations and a smoother strain stiffening response compared to the beams with the conventional thinner core. The paper also highlights the low shear wave speed of these auxetic foams compared to other porous polymers used in helmet and head protection applications, as well as potential uses of the quasi‐zero‐stiffness behavior here observed for the auxetic foam sandwich beam.