Numerical Simulations of Transverse Compression and Densification in Wood

Numerical modeling, such as finite element analysis (FEA), of complex structures and complex materials is a useful tool for stress analysis and for failure modeling. Although FEA of wood as an anisotropic continuum is used, numerical modeling of realistic wood structures, including details of wood anatomy and variations in structure within specimens, has been beyond the capabilities of FEA and other methods. In contrast, the recently-derive material point method (MPM) has features that make it amenable to analysis of realistic wood structures. To demonstrate the capabilities of MPM, simulations were done for wood in transverse compression. Some advantages of MPM are that it is easy to discretize micrographs of wood specimens into a numerical model, it can handle large deformations, it can model elastic-plastic cell-wall properties, and it automatically accounts for contact between cell walls. MPM simulations were run for softwood and hardwood loaded in either radial or tangential compression. The simulations reproduced many features of wood compression, gave insight into effects of wood anatomy on compression, and may be the first numerical calculations of realistic wood structures extended through to full densification without numerical difficulties.