Studies of the Explosion Expanding-Fracture Process of a Thin Cylindrical Shell

A damage-level function for describing the dynamic failure growth process is proposed in this paper. Starting from this function and using the hardening-viscoplastic constitutive equation as the material characteristic equation, analytical expressions of complete-fracture criterion of a thin cylindrical shell subjected to explosion expanding have been obtained under two approximate conditions (constant expanding velocity or constant strain rate). The analytical reslts demonstrate that there exists a maximum complete-fracture strain at an appropriate strain rate, which is called plastic peak. As an example, the results for mild steel indicate that the complete-fracture criterion derived in this article could be better to explain the experimental results given by Иванов and Chen et al. The complete-fracture plastic peak is nearly located at the point of strain rate e'*=4104 s-1 and strain *=60%~80%.