Study On Failure Characteristics And Influence Factor Of Explosion Metal Cylinders

The fracture process of explosion cylinder shell brings a complicated physical phenomenon which includes fracture of material and structure caused by high strain plastic deformation under impulsive load(~10sGPa).The research of fragments and mechanisms of explosion cylinder shell is significant to armament design and analysis which becomes the focus of millitary exploration.In this paper,the deformation and fracture behavior of exploded TA2 titanium alloy cylinders driven by varied charge conditions are studied experimentally by micro characteristic analysis of recycled fragments.A Numerical methods which analyze the law of shock wave's propagation along the wall thickness,the evolution of strain and the stress state is also designed to explore the effects of loading performance on fracture and mechanism.The results are as follows.(1)The shearing fracture of TA2 titanium alloy cylinders subject to a higher explosion pressure is initialed at the middle of specimen wall thickness where a region of damage and micro voids formed,and then propagates to the inner or outer surface.With decreasing the detonation wavelength,the damage and micro voids formed in the middle of wall thickness become more serious.When under lower detonation pressure,the cracks start from the inner surface,and extend indirection of 45° or 135° to the radial.Obvious expansion fracture of cylinder occurs and the fracture mode of several fragments become tensile-shear under much lower detonation pressure.(2)The finite element numerical analysis shows that: under higher pressure,the secondary plastic zone caused by wave propagation and reflection between the walls surface increase the equipment plastic strain in the middle zone of thickness.The cracks first found in the secondary plastic zone during the driven period propagate to the inner and outer surfaces along direction 45°or 135°to the radial.For lower blast loading,the shearing cracks originated in the inner surface,propagate to the outer surface along direction 45°or 135°to the radial during the free expanding period.(3)The morphology on the inner region of wall thickness is not the same under different explosion pressure.Crossed shearing slip bands or beams consist of deformed elongated grains and fine grains distributed along shear direction are found subject to a higher explosion pressure.When under lower detonation pressure,adiabatic shear band appeared at crack tip present fine grains which has the preferred growth direction,formed by dynamic recrystallization.The grain size in the region near the outer surface of cylinder is not much changed except a large number of twins appeared.