Abstract

Under the combined action of structure-process -load, the stiffness and stress distribution at the sealing interface of the ultra-high pressure diaphragm compressor cylinder head exhibit significant nonlinear and uncertain characteristics, resulting in damage to the sealing interface, diaphragm and sealing ring. This paper first establishes a finite element numerical model considering assembly process parameters based on sudden impact load conditions, and analyzes the dynamic characteristics under different assembly process parameters. It is found that some modal frequencies transition with bolt loosening. Then, the mechanical characteristics of the assembly interface of the compressor sealing system under sudden impact load were studied. The maximum equivalent stress at the assembly interface was 298.9 MPa, and the maximum deformation at the top of the air chamber was 0.167mm. Finally, the nonlinear effects of sealing ring compression rate, sealing ring diameter, and sealing groove structure on contact stress and sealing performance were obtained. The results show that as the compression ratio increases by 20% and 25%, the contact pressure at the sealing interface increases by 42.0% and 77.5%, respectively; When the compression rate is 25%, the width of the sealing groove increases by 0.5mm, and the maximum contact pressure decreases by 8.1%. The research on the dynamic characteristics and sealing performance of diaphragm compressors provides technical support for the structural optimization design of diaphragm compressors cylinder head.

Abstract

Diaphragm fatigue fracture stands as one of the primary failure modes in hydrogen refueling station diaphragm compressors, urgently requiring systematic investigation into the mechanical properties and fatigue reliability of diaphragms under actual service conditions. However, due to the complex contact state between the diaphragm and the gas cavity cover plate (gas passage, gas hole)/oil cavity support plate and oil distribution plate (oil passage, oil hole), it is difficult to accurately obtain the stress distribution state of the diaphragm. In this study, we conducted material property experiments on the diaphragm to characterize its constitutive parameters. A refined numerical simulation model of the cover platediaphragm-support plate was established to analyze the mechanical properties of the diaphragm group under different conditions. The influence of diaphragm thickness on stress distribution and fatigue life was also explored. The results indicated that high stress distribution areas were mainly concentrated in the cavity transition zone and in the overlapping area of the diaphragm and gas passage/oil passage. The temperature inside the diaphragm compressor cavity had a significant impact on the stress level of the diaphragm. When the cavity temperature reached 300°C, the maximum von Mises stress reached 1286 MPa. The optimization results of diaphragm thickness indicated that when the diaphragm thickness was within the range of [0.3, 0.5 mm], the diaphragm was at a low stress service level; considering both the fatigue life and deflection performance of the diaphragm, the diaphragm thickness should be selected as thick as possible within the range of [0.3, 0.5 mm]. The numerical simulation model of the diaphragm compressor and the structural optimization design method of the diaphragm proposed in this article have significant engineering implications for improving the fatigue life of diaphragm compressor diaphragms.OPEN ACCESS Received: 02/03/2025 Accepted: 13/05/2025 Published: 14/07/2025