Holes Formed in Thin Aluminum Sheets by Spheres with Impact Velocities Ranging from 2 to 10 Km/S

The dimensions of 96 holes produced by the impact of 2017-T4 aluminum spheres with various thicknesses of 6061-T6 aluminum sheets are presented and analyzed. The sphere diameters ranged from 1.40 mm to 19.05 mm and the sheet-thickness-to-projectile-diameter ratio, t/D, ranged from 0.008 to 0.618 with the majority of the tests having t/D ratios of less than 0.234. Impact velocities ranged from 1.98 km/s to 9.89 km/s. The measured hole diameters were normalized by dividing them by the diameter of the sphere that produced the hole. The normalized diameters of the holes are shown to scale when compared on the basis of t/D ratio. When the impact velocity was held constant, a relationship between the t/D ratio and the morphology of the lip structure surrounding the hole was noted. As the t/D ratio increased, the holes tended to be less circular and the lip morphology became more complex. The results of the analysis of all hole data was used to develop a description of the hole-formation sequence.