Study On The Dynamic Fracture Behavior And Failure Assessment Of Stainless Steel Cylindrical Shell Subjected To Explosion Pressure

Explosion Containment Vessels (ECVs) are devices used for fully containing the effects of explosion and its products. They can restrict the damage range of explosion shock waves and effectively protect personnel or equipment near from the explosion, so they’re widely used in scientific research, explosive metalworking, national defense and other fields. The explosion pressure, which changes dramatically in a small time-scale, is a kind of a very high rate loading essentially. As a result, the explosively loaded ECVs may undergo a fracture mode transition from brittle to ductile with the increased loading rate. Therefore, in order to further improve the design ability of ECVs, it is of great practical meaning to investigate the damage mechanisms and failure assessment method of vessels subjected to internal blast loading.Supported by National Science Foundation project " Research on adiabatic shear evolution and fracture profile prediction of explosion containment vessels"(Project NO.51005201) and "Research on damage mechanism and life prediction of cylindrical composite explosion containment vessels"(Project NO.50875236), the dynamic fracture behavior and failure assessment method of the explosively loaded stainless steel cylindrical shells were studied in this thesis. The main research work and conclusions are summarized as follows:(1) Experimental investigation on the dynamic fracture behavior of explosive-loaded stainless steel cylindrical shells. Explosion experiment has been carried out on a group of pre-cracked304stainless steel cylindrical shells. Scanning electron Microscope (SEM) observations and metallographic examination were conducted on the fracture surfaces. Features of shear localization dominated ductile fracture pattern was founded, such as elongated shear dimples on the fractured surface and highly localized slip bands in the microstructures.(2) Numerical study on dynamic failure assessment method of the pre-flawed cylindrical shells by using failure assessment diagram (FAD). The dynamic responses of cylindrical shells subjected to internal blast loading were analyzed; a numeric method for computing dynamic stress intensity factor (SIF) of structure defects based on3dimensional virtual crack closure technique (3D VCCT) was developed; a dynamic assessment method of ECVs using FAD was presented and verified by experimental results, which shows the result of the assessment method is in good agreement with the experimental result.(3) Research on crack propagation of the impulsive-loaded structures. A rate-dependent failure criteria for impulsive-loaded structures was established; comparison between the results of the rate-dependent failure criteria and LANL’s ductile failure criteria was conducted, which indicates the rate-dependent failure criteria is efficient in the estimation of crack growth under high rate loading.