Proposal of an Orthotropic Hyperelastic Model and Application to Fiber-Reinforced Rubber Seals in Electric Generator

In this paper, we propose an orthotropic hyperelastic model for the fiber-reinforced rubber material used as rubber seals in electric generators. The fiber-reinforced rubber is composed of rubber matrix material that is reinforced by two families of fibers. The mechanical properties is anisotropic on directions of two fiber families. We improve an anisotropic model by adding terms to the strain energy function to consider its mechanical properties in small deformation region. The energy functions of the fiber families was represented by power series of invariants of stretch and shear deformation in fiber families. Moreover, the proposed strain energy function was polyconvex in totality. In order to identify material parameter of the proposed model, biaxial tensile test result of the rubber matrix and uniaxial tensile test result of the fiber-reinforced rubber were approximated by the nonlinear least squares method. Finally, applicability to the fiber-reinforced rubber of proposed model by FEM simulation of tensile, shear and compression was demonstrated to evaluate the applicability of the proposed model to the rubber seal.