Geometry-Induced Instability in Twisted TPMS Gyroid Structures Manufactured from High-Strength Al7050

Abstract

Triply periodic minimal surface (TPMS) architectures enable tailored mechanical response in additively manufactured cellular materials; however, the role of global geometric reorientation in high-strength, low-ductility alloys remains unclear. In this study, the compressive behavior of twisted TPMS–gyroid structures fabricated from laser powder bed fusion (LPBF) processed Al7050 is investigated. Gyroid-based specimens with identical relative density and unit cell parameters were designed with increasing levels of continuous twist to isolate the effect of load-path reorientation. Quasi-static compression tests were performed to evaluate peak compressive stress, instability onset, deformation localization, Volumetric Energy Absorption (E_v), and Specific Energy Absorption (SEA). The influence of build orientation and post-processing heat treatment was also examined. The results show that elastic stiffness is largely insensitive to twist, whereas peak stress and collapse behavior are strongly governed by geometric reorientation. Moderate twist promotes distributed instability and improves energy-related performance despite limited deformation capacity, while excessive twist accelerates shear-dominated localization and premature collapse. These findings demonstrate that twist acts as a constraint-sensitive design parameter in Al7050 TPMS structures, with optimal performance confined to a limited geometric window defined by strength utilization and instability tolerance.