Tether analysis and stability investigation of space rocket launch offshore compliant platform in regular seas

This study investigates the stability of a multi-utility offshore platform designed for rocket launches, focusing on tether dynamics and platform behavior under operational and failure scenarios. The platform, modeled in ANSYS AQWA, features buoyant legs and a topside connected by ball-and-socket joints, allowing translational motion while maintaining independent rotations. The extended topside introduces pitch moments requiring stability checks. Free-decay tests reveal rigid heave and pitch motions (~3 s) and flexible surge motions (~150 s). Dynamic tether analysis under various sea states highlights that simultaneous tether failures critically affect platform stability, causing significant shifts in heave and pitch. Highlights Demonstrated topside stability in heave and pitch under multiple tether failure scenarios, highlighting the platform's robustness. Applied Mathieu's stability analysis and charts to assess tether stability under dynamic conditions, offering a novel approach to offshore rocket platform stability. Analyzed the impact of tether failure on tension distribution, revealing critical tension spikes affecting buoyant legs and platform stability. Utilized phase plot analysis to reveal the recentering ability of the platform and confirm its stability through elliptical shapes, offering a new method for visualizing the dynamic response of offshore launch platforms.