The following changes in Abaqus 6.9-EF may impact the analysis of input files from previous releases of Abaqus:
The domain decomposition iterative solver has been replaced by a new iterative solver. As a result, the SOLVER=DDM setting is no longer available for the *STEP option; use SOLVER=ITERATIVE instead. For more information, see “Iterative equation solver,” Section 6.1.
For general procedures using the iterative solver, the default tolerance for convergence of the relative residual of the linear system has changed from 10–6 to 10–3; the default tolerance is still 10–6 for linear perturbation procedures. You can adjust the default tolerance using the *SOLVER CONTROLS option. In addition, you can no longer specify the number of domains used by the iterative solver with the *SOLVER CONTROLS option. For more information, see “Iterative equation solver,” Section 6.1.
For implicit dynamic analyses that involve contact, Abaqus/Standard by default now uses a time integration scheme with more damping than in previous releases. To restore the previous time integration scheme, use the APPLICATION=TRANSIENT FIDELITY setting with the *DYNAMIC option. For more information, see “Dynamics enhancements,” Section 6.2.
Abaqus/Standard no longer uses the contact patch algorithm to track the association between slave nodes and master surface nodes. Therefore, the SLIDE DISTANCE parameter on the *CONTACT CONTROLS option has no effect on an analysis.