Large Strain Viscoelastic Material Model for Deformation, Stress and Strain Analysis of O-rings

Abstract

Primary aim of this paper is to investigate the mechanical behavior of an O-ring seal made of NBR rubber material using finite element method. Further aim is to identify the O-ring’s critical locations where it can fail under normal operating conditions. For these a large-strain viscoelastic material model was set up. The recommended strain range where the material model should be sufficient is 0-100 % for normal conditions, but when the effect of overload or the temperature is the question, the strain range should be 0-150 %. From designer point of view, a large-strain viscoelastic material model with a 5 parameter Mooney-Rivlin term is appropriate. To make sure the material model′s accurate response, uniaxial tension, pure shear and equibiaxial measurements are needed, completed with dynamic measurements with a DMTA machine. The results show two critical locations where the failure of the O-ring is expected. One is on the edge of the O-ring near the gap, when friction is present, the other one is under the edge near the gap.