A Finite Element Analysis on Isotropic Damage Propagation in Axisymmetric Structures

摘要

In this paper, a finite element analysis on isotropic damage propagation of the axisymmetric structures is performed based on the continuum damage mechanics. An isotropic damage model is proposed based on the generalized effective stress concept, the stiffness degradation is taken as a measure of damage. To describe the large deformation effectively, the kinematics based on the RU decomposition are used. For the contact boundary condition, the extended interior penalty method and the modified Coulomb's friction law are used. The finite element approximation of the nonlinear equation from the concept of the incremental total Lagrangian is carried out. To perform the integration of the rate-type constitutive equations, the extended Euler method with second order accuracy is used. As numerical examples, axisymmetric nose cones of rockets with various radii are analyzed under the external pressure loadings, and metal forming processes with axisymmetric shape are examined. In the case of nose cones, effects of damage implementation on the stress distribution are observed, and effects of friction on the distributions of residual stress and damage are investigated in the metal forming process.