Criterion for Mixed Mode Fracture in Wood

Abstract

The mixed mode fracture failure of eastern red spruce (Picea rubens) was investigated by means of single edge notch and center crack specimens with various crack inclinations in the tangential‐longitudinal plane with propagation in the longitudinal direction (i.e., TL system of crack propagation). These results demonstrate there is a definite interaction between failure stress intensity factors KI and KII during the mixed mode fracture of wood. These mixed mode data were supplemented by the fracture toughness (KIC) and pure mode II critical stress intensity factor (KIIC). Several mixed mode fracture failure criteria were compared. The criterion that could not be rejected is KI/KIC+(KII2/KIIC)=1.