Mechanistic insight and design optimization for rotary combined seal under high-temperature stress relaxation

The long-term reliability of rotary seals in high-temperature environments is compromised by material stress relaxation, which induces progressive leakage and eventual failure. This study investigates the underlying degradation mechanism through a coupled thermo-elasto-hydrodynamic lubrication model. The results reveal that stress relaxation causes a 30–40% decay in contact pressure and a ∼15% reduction in lubricant film thickness, precipitating interfacial failure. To counteract this degradation, a data-driven optimization framework integrating a neural network surrogate model and NSGA-II is developed. The optimized seal geometry recovers approximately 20% of the lost contact pressure and reduces film thickness thermal variability by ∼45%, demonstrating a potent design strategy to significantly enhance sealing durability under extreme thermal conditions.