A multiscale mechanics model for elastic properties of densified wood

We introduce a multiscale mechanics model for analyzing the elastic properties of super-strong densified wood (DW). Our model incorporates microstructural features such as microfibril angle and densification ratio, along with chemical parameters including degree of polymerization, crystallinity, and density of hydrogen bonds. At the nanoscale and microscale, the elastic properties of cellulose nanofibril and cell wall layers are derived analytically using the mechanics of composite materials. Finite element simulations based on representative volume elements are conducted at the mesoscale to obtain homogenized effective elastic properties at the macroscale. Our quantitative investigations validate that microstructural changes and alterations in chemical components significantly enhance DW's mechanical performance. Densification and chemical changes, especially increased cellulose content and reduced lignin, emerge as vital mechanisms for strengthening DW. The model's insights offer valuable guidance for optimizing the two-step preparation process of DW to achieve superior mechanical performance. Additionally, the versatility of the model allows for exploring the influence of cell dimensions and potential applications in designing bioinspired materials.