Shear stiffness and energy absorption of auxetic open cell foams as sandwich cores

Hong Chun Cheng, Fabrizio Scarpa, Tulio Panzera, Ian Farrow, Hua-xin Peng

Research output: Contribution to journalArticle (Academic Journal)peer-review

30 Citations (Scopus)
213 Downloads (Pure)


This work describes the identification of the shear modulus of open cell polyurethane thermoformed auxetic foams from 3-point 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 behaviour here observed for the auxetic foam sandwich beam.
Original languageEnglish
Article number1800411
Number of pages9
Journalphysica status solidi (b)
Issue number1
Early online date17 Dec 2018
Publication statusPublished - Jan 2019


  • auxetic
  • foam
  • shear
  • bending
  • experiments
  • energy absorption


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