Dynamic tensile deformation and fracture of metal cylinders at high strain rate

摘要

An experimental study is presented on the radial expansion of metal cylinders of internal diameter 52mm and wall thickness l-6mm, internally loaded with high explosives. A rotating mirror streak camera monitors the distance time (x-t) history of the cylinder wall, expanding under strain rate of 10~4-10~5s~(-1), till it is ruptured. Aluminium cylinder is found to rupture at strain (ε)of 75-150 %. For a fixed wall thickness, the rupture strain is found to increase with the strain rate. However, when the wall thickness is changed, a maxima is observed in the graph showing the rupture strain and strain rate relationship. Probably, aluminium follows the Ivanov rupture criteria. In deformation of copper cylinder the cracks initiation at strain of ε=30-50 % is followed by rupture at very high strain up to 300 %. Recovered fragments show wall thinning by 50-60% and also exhibit that the shear fracture dominates the radial fractures.