u2.04.02 Tips for implementing non-linear calculations

Summary

The objective of this document is to give advice to a user who wants to perform non-linear calculations with*Code_Aster*. The user of linear calculations will also find useful information and advice.

The following aspects will be addressed:

• meshing and modeling,

• loads and boundary conditions,

• materials and laws of behavior,

• non-linear resolution,

• memory/time management and optimization,

• error control and quality.

This document does not treat issues specific to dynamics.

• 1. Meshing and modeling
  • 1.1. General information on the choice of the degree of mesh and the choice of finite elements
  • 1.2. Choosing a formulation to treat almost incompressible problems
• 2. Loads, boundary conditions, initial conditions
  • 2.1. Core of the problem
  • 2.2. Precautions for applying loads
  • 2.3. The different types of boundary conditions
  • 2.4. The initial conditions
• 3. Materials and behaviors
  • 3.1. Choice of the law of behavior
  • 3.2. Tags of COMPORTEMENT
• 4. Nonlinear resolution
  • 4.1. Non-linearity and temporal discretization
  • 4.2. Numerical parameters for the nonlinear resolution algorithm
• 5. Memory/time management and optimization
  • 5.1. Executing a calculation for the first time
  • 5.2. Optimizing a calculation
• 6. Quality control
  • 6.1. Uncertainties about the data
  • 6.2. Modeling choice and data verification
  • 6.3. Controlling errors due to spatial discretization
  • 6.4. Time discretization errors
• 7. References