Fracture Toughness of Wood and Wood Composites during Crack Propagation

Mode I fracture toughness as a function of crack length of medium-density fiberboard (MDF), particleboard (PB), and Douglas-fir (DF) was measured using a new energy-based method. PB and MDF are examples of composites that develop fiber bridging during crack propagation, which causes their toughness to increase with crack length. Longitudinal cracks in DF also displayed fiber-bridging behavior, but only when the crack plane was normal to the...