ISO 19901-4 Fatigue Life S-N Curve Database (CSV)

ISO 19901-4:2021 ('Petroleum and natural gas industries — Offshore structures — Part 4: Design of steel structures for fatigue') defines standardized S-N curves for welded joints and base metals, categorized by detail type (e.g., T-joints, butt welds), fabrication quality, and environmental conditions (e.g., as-welded, cathodically protected). The CSV database implements this standard by encoding each curve as rows containing metadata (e.g., detail code, environment, design life category) and parametric coefficients required to compute fatigue damage per the linear Miner’s rule or spectral methods. For utility-scale solar trackers, these curves are applied to critical welds in torque tubes, foundation interfaces, and drive mechanisms subjected to millions of low-amplitude wind gust cycles and fewer high-amplitude stow/unstow events. Structural dynamics simulations—using time-domain or frequency-domain load histories derived from IEC 61215-2, IEC 61427-2, or site-specific CFD/wind tunnel data—are post-processed with rainflow cycle counting and S-N-based damage summation. The CSV format ensures interoperability with fatigue analysis tools (e.g., nCode DesignLife, ANSYS nCode, Python-based PyFatigue), enabling traceable, auditable, and standardized fatigue assessment across design iterations and certification bodies.