NUMERICAL MODELLING OF ADDITIVE MANUFACTURED HIGH-STRENGTH MARAGING STEEL TARGETS UNDER BALLISTIC IMPACT BEFORE AND AFTER HEAT-TREATMENT

The combination of ultra high-strength and the flexibility of additive manufacturing (AM) makes maraging steel produced by laser powder-bed fusion an exciting prospect for optimised armour systems. Good ballistic performance has been found in experimental studies, despite a tendency for fragmentation of the high-strength heat-treated maraging steel, exacerbated by AM defects. Fragmentation is a long-standing challenge in the numerical modelling of ballistic impact. This study evaluates the ability of two different failure modelling approaches to capture fragmentation in finite element simulations using the IMPETUS Solver: node-splitting and element erosion. The predicted ballistic limit velocity was conservatively within 10% of the experimentally determined value using both failure models for the non-heat-treated AM targets, despite only simple measures taken to account for the AM-induced anisotropy. The element erosion technique was found to under-predict the ballistic limit velocity of high-strength, heat-treated targets, with significant fragmentation, by 13%, compared to only 2% for node-splitting.