A novel constitutive model for the porosity related super-large deformation and anisotropic behavior of wood under perpendicular to grain compression

The perpendicular to grain compression behavior of wood is critical in designing timber structures. The finite element method has been widely utilized to investigate the behavior of wood. However, until now there is no suitable constitutive model of wood that can reasonably describe the behavior of the super-large deformation, volumetric compaction and the anisotropy of wood under perpendicular to grain compression. In this study, perpendicular to grain compression test on Masson pine wood was performed to investigate the structural behavior in three different stress states, namely uniaxial, lateral restrained, and circumferentially restrained. Further, a constitutive model considering the anisotropy of wood was developed where the governing functions are separately defined in longitudinal and transverse directions. The porosity of wood in the transverse plane was simulated by considering the volumetric compaction, whereupon the corresponding failure criteria, flow rules, and hardening rules were proposed and the equations were derived. The developed model was verified by comparing the predicted data with the test results. The developed model can simulate the super-large perpendicular to grain deformation and the anisotropy of wood simultaneously which is useful for the numerical analysis of wood members, connections, and structures.