Optimizing penetration resistance of Ni-Ti shape memory alloy fiber reinforced concrete under high impact velocity: a comprehensive study

This paper investigates the penetration resistance of shape memory alloy fiber reinforced concrete (SMAFRC) in protection engineering. Tensile and temperature residual stress tests on SMA wires with different pre-strains revealed that increasing pre-strain enhanced the wire elastic modulus, yield strength, and recovery stress, while reducing its elongation at break. Through pull-out tests, a peak bond strength of 3.2 MPa was observed on SMA wires at a 5 % pre-strain, a 33.3 % increase compared to SMA wires without pre-strain. Furthermore, the compressive strength of SMAFRC incorporated with high fiber content even exceeded 300 MPa. Subsequently, penetration tests on SMAFRC with varying SMA fiber volume ratios (0 %–7 %) and pre-strains (0 %, 2.5 %, 5 %) revealed that a 3 % fiber volume ratio optimally enhanced penetration resistance. At this ratio, the crater area, volume, equivalent diameter, and residual velocity of the projectile were significantly reduced. Finally, a validated 3D mesoscale model showed that SMA fibers significantly improve the penetration resistance of concrete, making SMAFRC a promising high-performance material.