Description: The contact iterations solution technique has been removed due to limited applicability and benefit of this technique. This solution technique was intended for analyses with small nonlinear effects other than contact, and it attempted to improve performance by avoiding global stiffness matrix assemblage and factorization while performing iterations to determine the correct contact status distribution. In practice, this solution technique often resulted in longer analysis times even if seemingly small nonlinear effects existed. Other contact enhancements in recent versions of Abaqus, such as contact stabilization and convergence tolerances associated with the resolution of open/close and stick/slip contact status, have tended to further limit circumstances in which the contact iterations capability would improve performance over the default approach of treating contact status changes with Newton iterations.

The current default contact settings are typically effective for analyses that previously relied on the contact iterations technique. An error message will be issued if the contact iterations technique is specified in an analysis. If removing this technique from an existing analysis results in performance or robustness degradation, removing other nondefault contact control settings is likely to improve the analysis behavior. In addition, the following contact options, which are not always active by default, may overcome convergence issues and improve performance:

• penalty enforcement of contact,

• the surface-to-surface contact formulation, and

• contact stabilization in the normal direction.