Damage and fracture mechanism of aluminium alloy thick-walled cylinder under external explosive loading

The damage and failure mechanism of aluminium alloy were investigated by means of the radial collapse of a thick-walled cylinder under high-strain-rate deformation. Adiabatic shear bands (ASBs) initiated at the inner surface of the aluminium alloy cylinder, and most of them were in spiral form along the cross-section of the cylinder towards counterclockwise direction. Tip of a shear band propagated along the direction of the maximum shear stress. The propagating trajectory of small shear band rather than developed shear band could be affected by grain boundary. The morphologies of ASBs such as bifurcation, crossing and annihilation were observed, and the evolution of ASBs was affected to a great extent by stress state. The nucleation of microcrack was mostly observed at the weak microstructure in ASBs. The coalescence of microcracks formed the crack within ASBs, and when the critical crack length is reached catastrophic fracture occurs.