Study on the effects of three surface imperfections on the performance of O-ring seals based on the finite element method

The performance of O-rings is crucial to the large variety of core equipment or components that employ O-ring seals. O-ring surface imperfections that meet quality standards are allowed to be put into service. However, the presence of surface imperfections will inevitably affect the performance of the O-ring seal. To this end, in this study, nonlinear finite element models of O-ring structures with an ideal circular cross section and three surface imperfections of parting line projection, backrind, and excessive trimming in accordance with ISO standards are developed. On this basis, their contact conditions and stress distributions are calculated, analyzed, discussed, and compared. The results show that the maximum contact pressure in the area where the imperfection is located increases and that the presence of the imperfection does not reduce the sealing performance. Backrind under low pressure conditions and excessive trimming do not affect the maximum Von-Mises stress. While backrind under high pressure conditions and parting line projection can make the maximum Von-Mises stress increase significantly. In particular, at a fluid pressure of 10 MPa, backrind causes a 21% increase in the maximum Von-Mises stress, while parting line projection causes a 198% increase. Such a large increase in stress will increase the likelihood of fatigue failure and breakage.