An integrated computational modeling framework for predicting fatigue crack growth in additive manufactured TPMS structures

Additive manufacturing (AM) based on Laser Powder Bed Fusion (LPBF) enables the fabrication of complex architected materials such as Triply Periodic Minimum Surface (TPMS) lattices, but introduces significant residual stresses and microstructural heterogeneity that strongly influence fatigue performance. This study investigates fatigue crack growth (FCG) in TPMS structures fabricated with LPBF technology by integrating multiscale modeling and fracture mechanics. Residual stresses are quantified through coupled thermo-mechanical finite element simulations, employing both layer-by-layer and path-dependent modeling approaches, while experimental fatigue crack-growth parameters are obtained from compact-tension (CT) specimens in as-built (AB) and T5 heat-treated, stress-relieved (SR) specimens conditions. The influence of printing direction, heat treatment, relative density, and scanning strategy is systematically evaluated through non-planar crack-growth simulations applied to IWP-TPMS lattices. Results show that vertically built structures accumulate higher tensile residual stresses, leading to increased effective stress intensity and shorter fatigue lives. Heat treatment reduces these stresses by ∼ 25%–35%, consistently extending fatigue life. Higher relative density (50%) architectures exhibit stronger sensitivity to printing orientation and T5 treatment due to increased stiffness and constrained ligament networks. AM scanning strategy shows minimal influence, except for 0°/90° and 45°/–45° patterns, which yield slightly lower tensile stress magnitudes, which in turn increases fatigue life. The proposed computational framework accurately captures fatigue crack-growth paths and life predictions, agreeing markedly well with experimental findings, offering new insight into how printing direction, heat treatment, and relative density collectively govern fatigue performance in TPMS architectures. • Thermo -mechanical models predict TPMS fatigue crack growth accurately. • Printing direction affects residual stress and fatigue life in TPMS lattices. • Heat treatment reduces residual stresses and improves TPMS fatigue resistance. • Fatigue crack growth simulations accurately capture 3D crack paths.