Impact of porosity-graded strategies on the mechanical response and energy absorption of additively manufactured Sheet-type Gyroid-based graded porous structures

• Impact of porosity-graded strategies on mechanical performance of Gyroid was studied. • The highest strength was achieved by QuaC strategy due to central layered reinforcement. • Superior energy absorption up to 24.60 kJ/g and structural stability were obtained. • Mechanism of enhanced mechanical performance in graded Gyroid structures was elucidated. This study elucidates the impact of porosity-graded strategies on the printability, mechanical response, deformation behavior, and energy absorption of Sheet-type Gyroid-based graded porous structures (SGGPSs) fabricated via laser powder bed fusion (LPBF). A MATLAB-based parametric modeling framework was established to generate SGGPSs with continuous porosity transitions using six gradient functions: linear (Lin), exponential (Exp), logarithmic (Ln), quadratic-concave (QuaC), quadratic-convex (QuaV) and uniform (Uni). Results demonstrated that mass and porosity deviations between the fabricated and designed SGGPSs ranged 13.5 %–25.1 % and 13.5 %–15.7 %, respectively, due to powder adhesion and surface irregularities. Among all variants, the QuaC variant exhibited the highest yield strength of 205.2 MPa, which was 1.55 times greater than the Ln variant, owing to its central layered reinforcement design rather than overall mass. The structural stability of LPBF-fabricated SGGPSs was enhanced through layer-by-layer collapse and slip deformation, facilitating smooth stress transfer and mitigating localized failure. Stress concentrations within high-porosity regions led to the formation of rigid support layers, thereby prolonging the stress plateau phase. The LPBF-fabricated SGGPSs achieved superior energy absorption capacities ranging 12.75–24.60 kJ/g, attributed to sustained plateau stress and delayed densification. These findings offer valuable insights for design and application of graded TPMS structures for lightweight engineering components.