Dynamic J Integral and Dynamic Stress Intensity Factor Distributions along Naturally and Dynamically Propagating Three-Dimensional Fracture Fronts

To the best of the authors' knowledge, any fracture parameter such as the dynamic J integral for a naturally and dynamically propagating crack front has not been evaluated. In our previous experimental study, high-speed photographs of dynamically propagating crack fronts in DCB specimens were firstly recorded. In this paper, first, to overcome difficulties in three-dimensional dynamic fracture simulation, a three-dimensional moving finite element method together with an automatic element control method is developed using a mapping technique. Next, to make it possible to evaluate the dynamic J integral along the dynamically propagating curved crack front, an equivalent domain integral method of the dynamic J integral is developed. Furthermore, to accurately evaluate dynamic stress intensity factors along the curved crack front, the component separation method of the dynamic J integral is also developed. Based on these simulation technologies, the generation-phase simulations are carried out, using the experimentally recorded histories of three-dimensional dynamic fracture events in 20mm thick DCB specimens. The distributions of the dynamic J integral and stress intensity factor along the actual dynamic fracture fronts are firstly elucidated. Based on these results, pertinent mechanism of three-dimensional fracture is also discussed.