Fast Fracture Resistance and Crack Arrest in Structural Steels.

摘要

Measurements and calculations of unstable fracture and fracture arrest in 12.7mm-and 25.4mm-thick,high-strength SAE4340steel and A517F steel plates are described. A fully dynamic analysis of unstable crack propagation and arrest in the DCB (double cantilever beam)-test piece is derived. The technique is based on the beam-on-elastic-foundation model of the DCB specimen used previously but with the simple beam and foundation representations replaced by a Timoshenko beam and a generalized elastic foundation. Crack speeds,energy levels,and the crack length at arrest are calculated with this model using finite-difference method and are compared with the measurements. The kinetic energy imparted to the test piece is recovered and contributes to the crack driving force. It follows from this that fracture arrest is controlled by the history of energy dissipation throughout the entire propagation event,rather than on Ka, a single static toughness value calculated at the arrest point. (Modified author abstract)