S. A. Atroshenko

Impact failure of metallic rings by a magnetic pulse technique

Metallic rings made of D16 aluminum alloy are studied upon the application of a distributed radial load by a magnetic pulse technique. Two approaches making it possible to decrease the period of the sin-wave load by seven and fifty times are developed. In addition, they allow one to determine the instant of rupture of the ring from a flash arising at rupture with the help of a photodetector. Simultaneously, the load pulse and a signal from the photodetector are displayed with a digital oscilloscope. It is shown that, when the load pulse shortens, the ductile component of fracture declines and the samples fail in a more brittle manner.

Crack propagation upon dynamic failure of polymethylmethacrylate

Crack propagation in polymethylmethacrylate shock-stressed by a pulsed magnetic field is experimentally investigated. The failure type as a function of the distance from the crack tip is analyzed, and the failure diagram is constructed. The surface failure energy is estimated. The tilt angles of mesocracks are correlated to the failure type.

Fracture of metallic rings during magnetic-pulse shock loading

Metallic rings made of aluminum and copper foils are studied after the action of a distributed radial magnetic-pulse load. Two loading approach modifications allowed us to substantially decrease the period of an applied sinusoidal load and to determine the time from load application to sample failure. A method is proposed to estimate the radial force on a metallic ring from coil turns. The profiles of radial pressure on the inner ring surface are measured, and the circumferential tensile stresses in ring fracture are determined. Microstructural studies of failed ring samples show that they underwent dynamic recrystallization. It is found that, as the operating load period shortens, the fraction of the ductile component in a fracture surface decreases and the samples undergo more brittle fracture.

Dynamic fracture of the surface of an aluminum alloy under conditions of high-speed erosion

The kinetics of fracture and deformation of the standard aluminum alloy AD1 and a similar alloy subjected to severe plastic deformation by high-pressure torsion under conditions of high-speed erosion has been investigated. It has been shown that, with an increase in the loading rate, the fraction of the brittle component on the fracture surface of the standard material, as well as the thickness of the damaged layer, increases more significantly than that for the material after the severe plastic deformation by high-pressure torsion. A relationship of the surface roughness of the material after the erosion with the loading rate and the thickness of the erosion-damaged layer has been established.

Influence of the reversible α–ε phase transition and preliminary shock compression on the spall strength of armco iron

Full wave profiles are used to determine the Hugoniot elastic limit and the spall strength of armco iron samples with an as-received structure and the samples recovered after preliminary loading by plane shock waves with an amplitude of 8, 17, and 35 GPa. The measurements are performed at a shock compression pressure below and above the polymorphic a–e transition pressure. Metallographic analysis of the structure of armco iron shows that a developed twinned structure forms inside grains in the samples subjected to preliminary compression and recovered and that the twin concentration and size increase with the shock compression pressure. The spall strength of armco iron under shock loading below the phase transition pressure increases by approximately 10% due to its preliminary deformation twinning at the maximum shock compression pressure. The spallation of samples with various structures at a shock compression pressure above the phase transition proceeds at almost the same tensile stresses. The polymorphic transition in armco iron weakly affects its strength characteristics.