Abstract: The test result of the film gas permeability test device basing on differential pressure is affected by the seal performance of test device, the environmental temperature and the performance of pressure and temperature detector. When the performance of pressure and temperature detector is given and the test temperature is relatively stable, the test result is decided by seal performance of test device, when currently available seal material and seal technology are used, the seal performance is decided by seal structure and corresponding structure ratio. Based on this, the solving expression of double seal structure system critical time is proposed. The features of pressure change and time flow resistance capacity constant about double seal structure are analyzed. Under the condition of limited total seal volume, the optimized structure ratio of double seal structure is obtained. The corresponding simulation is done, and experimental results are given. The results show that the optimization of double seal structure is correct and reasonable. It provides a theoretical basis for practical application about double seal structure optimization of the gas permeability test device.

Key words: Double seal structure, Optimization, Structure ratio, System critical time, Time flow resistance capacity constant, Gray-gradient co-occurrence matrix, High-order spectrum, PSO-SVM, Rail vibration responses, Wheel flats