Crack Propagation Fracture Toughness of Several Wood Species

In materials with process zones, such as fiber-bridging zones in wood, it is crucial to characterize fracture toughness as a function of crack growth, known as the material's R curve. Here, a new fracture testing protocol developed to measure continuous R curves was used on six different species of solid wood—Douglas fir, Ponderosa pine, cedar, hemlock, balsa, and oak. Importantly, the new method uses monotonic loading, because unloading phases,...