Fracture behavior of explosively loaded spherical molded steel shells

Experimental and numerical works are made to study the fracture of explosiv ely loaded spherical molded steel shells. The first series of experiments i ncluded three sawdust recovery shots to save fragments for examination. In this series, detonation was initiated from the center of the sphere. Result s of the experiments show that two types of fractures are observed in spher ical shells: radial and shear as in cylindrical shells. Spall fracture is a lso observed in spherical shells. To assist understanding of the experiment al results, a computer simulation of expanding shells is performed to provi de information on the stress, strain, strain rate and position of each elem ent of the shell wall as a function of time after detonation. For t = 7.5 m us after detonation, triaxial non-uniform strain prevails in the middle of the thickness of the wall. The peak of the stress equals to 6.5 GPa and exc eeds the spall strength of carbon steel. In the second series of experiment s., spall fracture is suppressed by displacing the point of detonation init iation from the center to periphery of HE charge. (C) 2001 Elsevier Science Ltd. All rights reserved.