Fatigue Life Assessment of Underwater Vehicle Pressure Hull due to Corrosion

The operation of underwater vehicles exposes the pressure hull structure to continuous contact with seawater, making corrosion an unavoidable phenomenon. Over time, corrosion degrades the structural integrity of the hull, reducing its fatigue resistance and overall safety. This study investigates the impact of corrosion-induced material thinning, particularly around the penetration areas of the pressure hull, on its structural performance. Using Finite Element Method (FEM) simulation, both corroded and non-corroded hull models are analyzed at an operational depth of 250 meters. The results show that encircling corrosion of penetration hull leads to a 9.93% increase in equivalent stress, a 92.35% reduction in fatigue life, and a 9.04% decrease in Safety Factor (SF). These findings demonstrate a direct relationship between material degradation and structural vulnerability, where reduced wall thickness due to corrosion increases stress concentration, thereby accelerating fatigue damage and reducing the safety margin. This emphasizes the importance of accounting for corrosion effects on the operational aspect of underwater pressure hulls to ensure long-term reliability and safety.