I came to a problem with Abaqus which considering two Sections that share nodes with the same material generate different results with a model that uses one Section. I was wondering how Abaqus want to solve this issue.

• The test case I created to study this problem is very simple.
  • I created two cubes with the same dimension.
  • I partitioned one cube into half. Therefore, nodes are shared along the common surface.
  • I assigned Section-1 and Section-2 to cube-1 and section-1 to cube-2 with the same material.
  • I constrained the bottom area and applied displacement control on the top area.
  • I considered a simple static analysis.
  • To me, the two cubes should behave the same under any compression since they use the same material, same element size, and they shared nodes.

• The problem
  • Abaqus appears to consider an interface between Section-1 and Section-2 and produce artificial stiffness.
  • I plotted the stress along two paths
    • The common line
    • A vertical line
  • Stress graphs clearly show of existing an interface which is not actually there.
  • Same would happen with strain plots along those paths.

• This is a problem and using multiple section in a material should not effect the results.

• Note
  • If I replace section-2 with section-1 in the input file and run it using command line, the results of the two cubes will be similar.