Coupled mass diffusion and structural deformation of elastomer seals exposed to rapid gas decompression

摘要

A sequentially coupled structural-mass diffusion model has been proposed to evaluate the behaviour of elastomer O-rings exposed to rapid gas decompression in the presence of CO2. The coupling between mass diffusion and the structural deformation of the O-ring was achieved by employing the Peng-Robinson equation of state and two user-subroutines to evaluate the pressure exerted by the rapidly expanding gas. The finite element analysis (FEA) model has been used to evaluate stress and strain distribution inside the O-ring during rapid gas decompression. It was shown that the nominal stresses go through a stress-state change from compression to tension during the decompression cycle, and the strain rate during the stress-state change is dependent upon the decompression rate. The FEA model revealed that the elements in the centre region of the O-ring's cross-section experience high tensile strains and stresses during each decompression cycle.