Investigation into the macro-micro characteristics of grooved PLUS seals for landing gear actuator

Purpose This study aims to address critical leakage and wear challenges of high-pressure reciprocating seals in aircraft landing gear actuators. It investigates the macro-micro sealing performance of grooved PLUS seals under extreme conditions (35 MPa) and multi-variable parameters (compression size, temperature, reciprocating speed, roughness), filling the research gap in PLUS seals’ high-pressure multi-scenario characteristics. Design/methodology/approach A thermo-fluid-structure coupled model based on mixed lubrication theory was developed. Multivariate operational parameters (compression ratio, −55°C–135 °C temperature, 0.1–0.5 m/s speed, 0.4–6.3 µm roughness) and geometric features (oil-trapping grooves) were systematically analyzed to evaluate micro-contact pressure, oil film thickness, friction and leakage. Findings Increasing compression ratio reduces leakage but elevates friction; temperature impacts rubber modulus non-linearly, altering wear and leakage; higher speed increases dynamic pressure-induced leakage/friction; roughness enhances oil film thickness but worsens both friction and leakage. Oil-trapping grooves balance sealing-lubrication-pressure resistance via localized lubrication and micro-pressure regulation. Originality/value To the best of the authors’ knowledge, this is the first study to systematically characterize grooved PLUS seals under 35 MPa high pressure, revealing multi-parameter influence laws. The hybrid lubrication model and structural design insights overcome the leakage-friction control bottleneck in high-pressure applications, providing a novel theoretical foundation for elasto-hydrodynamic lubrication and critical guidance for aircraft hydraulic seal optimization. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2025-0233/