Description: Improvements to the small-sliding, surface-to-surface contact formulation have been made so that this formulation acts as a limit case of the finite-sliding, surface-to-surface formulation. Results obtained with these two formulations will be consistent for cases in which the relative motion between the interacting contact surfaces is very small compared to nearby surface facet sizes and curvatures.

A key advantage of the new formulation is improved contact behavior when elements underlying the slave surface have 6-node triangular faces or 8- or 9-node quadrilateral faces.

All small-sliding contact formulations are based on simplifying assumptions that sometimes reduce analysis cost; however, nonphysical results will occur if these assumptions do not hold. Refer to “Using the small-sliding tracking approach” in “Contact formulations in Abaqus/Standard,” Section 33.1.1 in the Abaqus Analysis User's Manual, for a discussion of these assumptions. It is the user's responsibility to judge whether the simplifying assumptions are appropriate; if you are uncertain, it is advisable to use a finite-sliding contact formulation.

One characteristic of the new small-sliding, surface-to-surface contact formulation is that multiple slave nodes participate in individual contact constraints; whereas preexisting small-sliding contact formulations use a single slave node per contact constraint. Tied contact defined using contact pairs is affected by the formulation changes, but surface-based tie constraints continue to use a single slave node per constraint; therefore, these two tie methods no longer use a consistent constraint formulation.