An Example of Hole Diameter in Thin Plates Due to Hypervelocity Impact

An equation was derived to calculate or predict the diameter of a hole which forms in a thin plate as a result of the normal impact from a high-velocity steel particle. The calculated diameter for aluminum and stainless steel plates in the thickness range 0.010 to 0.063-in. (0.25 to 1.6 mm) was observed to be larger than the experimental value since material properties were neglected in the derivation of the mathematical expression. Excellent agreement between the calculated and experimental values was obtained when a 10% relaxation effect was applied to the calculated hole diameter. Concordance was observed over the impact velocity range of approximately 9000 to 16 100 ft/sec (2743 to 4907 m/sec). The holes observed in aluminum plates 0.090 to 0.187 in. (2.3 to 4.7 mm) in thickness were larger than those observed in plates 0.063 in. (1.6 mm) and thinner. Moreover, the mathematical expression was not applicable to these thicker plates. This nonconformity was attributed to a difference in impact mechanism.