Topology-guided design of recoverable NiTi TPMS lattices for low-speed impact penetration resistance

The integration of functional architected lattices into composite constructs offers a transformative pathway for impact-resilient structures capable of damage recovery. This study investigates the low-speed penetration response and thermally induced shape recovery of laser powder bed fused nickel-titanium (NiTi) shape memory alloy lattices based on triply periodic minimal surface (TPMS) architectures. Diamond, Gyroid, I-WP, and SplitP topologies with relative densities of 15–25% are subjected to impact energies of 50–350 J. Force-time, force-penetration, and velocity-penetration responses are analyzed to link topology and relative density to penetration resistance, energy dissipation, and residual damage. Recovery is quantified from the depth, volume, and equivalent radius of the residual imprint before and after thermal activation. Among the tested configurations, the Diamond topology at 25% relative density and 200 J shows the best balance between impact resistance and recoverability, achieving approximately 60% imprint volume recovery after heating. This response is potentially attributed to a broader stress-induced martensitic transformation zone that promotes recoverable deformation while limiting localized plastic damage. A physics-constrained regression framework is further used to reconstruct velocity-penetration histories and estimate critical penetration limits. The findings provide design guidelines for recoverable NiTi architected materials combining penetration resistance, energy dissipation, and thermally activated recovery.