Evaluation on Dependence of Ductile Crack Propagation Resistance on Crack Velocity

Plastic strains were measured near a propagating ductile crack in drop-weight tear tests (DWTT). Plastic work evaluated from the plastic strains agreed with crack propagation energy evaluated from dynamic load versus displacement curve. Furthermore, plastic strains were measured near a propagating ductile crack in a full-scale burst tested pipes. Plastic work of the burst pipe was found to be much larger than that of the DWTT. Values of the plastic work of the DWTT and the burst pipe were plotted against crack velocity to construct crack resistance curve. Reason to the increased crack resistance with crack velocity was understood as a dependence of plastic strain distribution on crack velocity by elasto-plastic dymanic finite element analysis.