The following change in Abaqus 6.11 may impact the analysis of input files from previous releases of Abaqus:

• The enhanced general contact tracking algorithm for edge-to-edge contact in Abaqus/Explicit is now used by default (*CONTACT CONTROLS ASSIGNMENT, TYPE=ENHANCED EDGE TRACKING). This algorithm utilizes more local information than the alternative tracking algorithm (TYPE=EDGE TRACKING) in tracking contact between edges and typically reduces the extent of global tracking required.

• The combination of second-order triangular slave faces, a node-to-surface contact formulation, and strictly enforced hard contact conditions is likely to cause poor convergence behavior and/or noisy contact pressure predictions. This combination, which may be present unintentionally in your existing models, is now identified with an error message during batch preprocessing so that you can modify the model to resolve potential problems (“Disallowed combination of features at contact interfaces,” Section 11.7).

For a complete list of changes to the Abaqus input file interface, refer to Chapter 16, “Summary of changes.”