Microleakage at circumferential gasketed joints of low-to-vacuum tubes: An experimental and computational study

The long-term sealing performance of circumferential gasketed joints is critical for maintaining low-vacuum environments in maglev transit tubes. This study investigates time-dependent microleakage resulting from gasket stress relaxation. We develop a novel multi-scale model that integrates macroscopic Hertzian contact mechanics with microscopic porous media flow theory. The formulation uniquely incorporates both the Klinkenberg gas slip effect, essential for low-vacuum conditions, and time-dependent contact pressure decay due to stress relaxation. Experimental validation using a specially designed apparatus simulating coupled “pre-compression and low-to-vacuum” service conditions of ethylene propylene diene monomer gaskets demonstrates the model's ability to capture increasing microleakage rates over time. While the theoretical model shows systematic overprediction, application of an empirical calibration factor (ζ = 0.859–0.934) effectively compensates for idealized elastic contact assumptions. Parameter analysis reveals microleakage rate increases with vacuum pressure, surface roughness, and gasket hardness, but decreases with initial contact pressure. This coupled multi-physics approach provides a predictive framework for assessing long-term airtightness in gasketed joints, with significant implications for the design and maintenance of low-vacuum transportation systems.