Evidence of negative Poisson's ratio in wood from finite element analysis and off-axis compression experiments

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.The microstructure of wood is highly anisotropic, which suggests that this material could exhibit unusual elastic properties. A few studies have suggested the possibility of auxeticity, or negative Poisson's ratio (NPR) in some wood samples. In order to conclusively confirm that wood does show NPR, we have used a combination of geometric modelling, finite element analysis (FEA) and off-axis compression testing. The geometric model indicates that idealised thin-walled wood cell structures should generate NPR of −1, FEA suggests that more realistic cell arrays can attain NPR, to −0.27, and compression tests show that some NPR – to −0.74 – remains in real wood samples. These results could help design “engineered-wood” laminates products with tailored elastic properties