Leakage–friction optimisation of a composite dynamic seal for continuous-rotation electro-hydraulic servo motors using a hybrid PSO–GA algorithm

Abstract

Dynamic seals play a critical role in the efficiency and reliability of continuous-rotation electro-hydraulic servo motors operating under high-pressure, low-speed conditions. To mitigate stress concentration while maintaining stable contact, a multi-protrusion composite seal combining nitrile rubber and polytetrafluoroethylene is proposed. An axisymmetric finite-element contact model is integrated with inverse-Reynolds film reconstruction and a local Couette–Poiseuille evaluation to quantify leakage and viscous friction. Seal geometry is then optimised as a bi-objective problem using a two-stage particle swarm optimisation–genetic algorithm (PSO–GA) strategy, where PSO pre-optimises and seeds a multi-objective GA to generate a dense Pareto front. At the selected operating point, the optimised design reduces leakage from 1.483 × 10⁻⁸ to 7.653 × 10⁻¹⁰ kg/s and viscous friction from 0.0587 to 0.0240 N, while improving contact-stress distribution and reducing internal stress concentration. The proposed FEA–lubrication–optimisation workflow enables an efficient trade-off design between leakage and viscous friction for rotary sealing applications.