Product: Abaqus/Explicit
Benefits: You may notice more accurate contact response for some Abaqus/Explicit models involving beams or shells.
Description: General contact in Abaqus/Explicit has the following enhancements related to thickness offsets:
Slip increment calculations for friction account for incremental rotation of shell and beam thickness offsets. Previously, slip increment calculations were based on tangential components of surface node translations alone.
The effect on the results due to consideration of incremental rotation of thickness offsets for friction is very small in most cases but is significant in some applications. Figure 10–1 shows an example in which surface thickness significantly affects slip increment calculations (and, therefore, proper enforcement of sticking conditions). This example involves a shell surface in frictional contact with a roller guide, with no relative sliding in the contact region. The reference surface of the shell (which contains the shell nodes) is offset from the reference surface of the roller in the contact region by the half-shell thickness. As shown in the figure, some difference in tangential motion between the two reference surfaces should exist due to rotation of the thickness offset. Assuming that the axis of the roller has no translational motion, incremental displacements of points on reference surfaces in the sticking contact region should be (and now are) proportional to the radial distance from the roller axis for this type of simulation (even for very small increment sizes).
Each frictional and normal contact constraint should generate zero net force and zero net moment among all nodes associated with the constraint; however, in previous releases frictional constraints in Abaqus/Explicit would generate a net moment when reference nodes were offset from the contact interface. Now, frictional constraints apply a moment to reference nodes offset from the contact interface due to shell or beam thicknesses, to oppose the net moment associated with the frictional force couple. Figure 10–2 shows an example of this in the context of the same shell-on-roller example as Figure 10–1. The applied nodal moment shown in Figure 10–2 cancels the moment of the associated frictional force couple, such that the net force and moment associated with the frictional constraint are zero.
