Understand the
physics of the problem:
- It is vital to understand the physics behind any problem. For example:
·
How does the actual structure behave for the
applied loading
·
How is the structure constrained at different
locations
·
How are the different components connected to
each other
·
What is the nature of the loads acting on the
structure
- We make many assumptions and approximations in any analysis, which have to be reasonable and justifiable. For example:
·
Is the chosen material model appropriate?
·
Are the element types properly chosen
·
Is the mesh size appropriate
·
Is contact properly defined (choice sliding
algorithm, friction coefficient, surface behavior etc.)
Build up the model
slowly:
- The most important way to help Abaqus find a converged solution is to build up the model piece by piece
·
Do not put every complexity and detail directly
in the first attempt-it probably will not work
- Start with the simplest model possible-perhaps one with contact but no plasticity, friction, or nonlinear geometry-this would give valuable insight into how the model behaves
- Add complexities (friction or plasticity) one at a time. Doing this will limit the number of questions to consider if a convergence problem arises.
- Although it might seem as if this process will increase the time needed to perform the analysis, in fact it often reduces the time because debugging a large model with convergence problems can take days or weeks.
Provide reasonable
values:
- Make sure that the units of the material properties (especially density) are consistent with the geometry and loads in the model.
- Make sure that the material properties provide sufficient stiffness to resist the applied loads, or plan accordingly and use the appropriate analysis techniques.
- Give reasonable values for the minimum increment size and the maximum increment size (or use the defaults).
- Use the message file or job diagnostics to identify the proper cause(s) for nonconvergence
