Using crack propagation fracture toughness to characterize the durability of wood and wood composites

We measured fracture resistance curves (or R curves) for laminated veneer lumber (LVL) made with Douglas-fir veneer and polyvinyl acetate resin and for solid wood Douglas-fir. The LVL and solid wood R curves were the same for initiation of fracture, but the LVL toughness rose much higher than solid wood. Because a rising R curve is caused by fiber bridging effects, these differences show that the LVL resin has a large effect on the fiber...