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

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.