Experimental and numerical study of peculiarities at high-velocity interaction between a projectile and discrete bumpers

A high-velocity impact interaction of a polyethylene projectile (15 mm diameter) and aluminium projectile (6.35 mm diameter) with string and mesh bumpers (made of steel strings of 0.5–1.0 mm in diameter) was investigated experimentally and numerically. The study was aimed on detecting the projectile fragmentation peculiarities during projectile interaction with discrete bumpers. Since polyethylene has lower penetration resistance than aluminium, the effects inherent to discrete bumper penetration into the projectile must be more obvious for polyethylene. The string bumper is a set of parallel strings lying in a plane. The geometry of the string bumper which is simpler than the geometry of the mesh one also allowed one to get more understandable distribution of fragments on a thick aluminium witness-plate which was imposed behind the studied bumper to register the results of impact interaction for further analysis. The projectile velocity varied in the range of 1.7–3.8 km/s. The geometrical properties of such bumper-projectile system were characterized by two geometrical parameters: the parameter κ characterizing the bumper discreteness and equal to cell aperture-string diameter ratio, and the parameter ɛ defining the average number of cells falling within the projectile diameter.