THE RELATION BETWEEN THE PENETRATION CAPABILITY OF LONG RODS AND THEIR LENGTH TO DIAMETER RATIO

Recent experimental studies, on the penetration of long rods into semi -infinite steel targets, reveal some features which cannot be predicte d by the conventional 1-D penetration model of Alekseevskii and Tate. This paper presents experimental results together with 2-D simulations which were performed in order to investigate this discrepancy. Specif ically we are interested in the question of whether the normalized pen etration curve-P/L (P is penetration depth, L is penetrator length)-is dependent on penetrator's length to diameter ratio in the range of L/ D = 10-40. Both experimental and simulation results show a decrease of about 15% between P/L values for L/D = 10 and 20 rods as well as for L/D = 20 and 30. These, rather large, differences are discussed in ter ms of material parameters which are resonsible for the discrepancy bet ween the 1-D model and both experiment and simulation. Moreover, we ha ve simulated the penetration of long rods having zero yield strength. Our results show that for large aspect ratios (L/D > 30) these weaker rods penetrate more than those with their full yield strength. This cr ossover phenomenon is both counterintuitive as well as opposed to the predictions of the 1-D model for this combination of rod-target materi als.