r5.03.15 Viscoplastic behavior with damage to CHABOCHE

Summary:

The visco-plastic model coupled with isotropic Chaboche damage (originally developed to successfully predict the lifespan and cracking of modern turbojet blades) is used for calculations to predict the failure time of structures at high temperatures.

This model is implemented in Code_Aster under the name of VENDOCHAB; the speed equations are integrated numerically by an explicit Runge-Kutta diagram of order 2 with automatic division into local sub-steps according to an estimate of the integration error (nested Runge-Kutta method, confer [R5.03.14]), or by an implicit integration method [R5.03.01].

Tests SSNV126 and SSNV183 validate the integration of this model. The validation document [V6.04.126] provides the analytical solution for an isothermal uniaxial creep test.

Table of Contents

• 1. Introduction
• 2. Formulation of the model
  • 2.1. Theoretical framework
  • 2.2. Model equations
• 3. Calculation of material parameters
• 4. Implementation in Code_Aster
  • 4.1. Resolution algorithm
  • 4.2. Implicit integration of the behavioral relationship
  • 4.3. Optimized implicit integration
• 5. Meaning of internal variables
• 6. Bibliography
• 7. Description of document versions