Numerical investigation of climate change impacts on European wood species vulnerability

摘要

Moisture levels are considered as a critical environmental impacting factor for wood and its components, as the moisture content (MC) influences virtually all the physical and mechanical properties. Adsorbed moisture is known to cause significant dimensional changes, as well as changes in mechanical properties such as the modulus of elasticity, stress factors and brittleness. In green wood, water droplets moved away from the cell lumens around the crack tip. Drying of wood induces micro-cracking and crack bridging as toughening mechanisms. To quantify the effect of humidity, fracture patterns and properties at various moisture levels are numerically investigated. Finite element simulations were performed on a modified Douglas Mixed-Mode Crack Growth specimen (MMCG). The crack growth process as well as the opening crack under temperature and moisture variations were calculated under various mixed mode ratios, and mixed modes energy release rates were evaluated. The distributed damage patterns in the most stressed regions between the area where concentrated force is applied and the notch plane where the fracture initiates is also taken into account here.