Numerical and experimental study on the friction of O ring for hydraulic seals

O-ring is one of the most widely used sealing components in hydraulic seals to prevent oil leakage. In triaxial test equipment, however, due to the existence of O-ring between the transmission rod and the sealing components, the accuracy of the measurement can be affected because the seal friction is also recorded by the external force sensor. In order to study the influencing degree of the seal friction, a friction model is established with phi 30 rod diameter. The axial friction, maximum friction stress and maximum contact stress of the O-ring are analysed using finite element method as the confining pressure varying from 50 to 300 kPa. Then the friction is measured experimentally. A good agreement has been obtained through the comparison between the numerical and experimental results, which indicates that the numerical simulation can be fully applied in a medium/huge triaxial apparatus with higher confining pressure. In the end, a transmission rod with phi 120 diameter is further investigated. The discrepancy is observed as the movement direction of transmission rod reverses. This study provides a theoretical basis for the estimation of the friction error, which would be beneficial for engineers to improve the measuring accuracy.