Learning Forum

[peteroznewman]

It is best to avoid using Bonded Contact with non-linear materials anywhere near locations of high stress or high stress gradient.

Instead use Shared Topology by clicking on the Share button on the Workbench tab in SpaceClaim.

Even after doing that, it is still possible for stress in an element to exceed the ultimate stress of 770 MPa.

What did you use for the Tangent Modulus for the Bilinear Hardening slope? That slope continues along the strain axis to infinity so 770 MPa is just one point along that slope. If the load continues to increase, the stress continues to increase.  What you can do, after you removed the bonded contact, is to note the simulation time when the 770 MPa is reached and note the load when that occurs as the Ultimate Load.

One other problem is extrapolation of stress from the internal Gauss points out to the corner nodes. When the elements are large, that can cause a significant increase in the reported stress. Make sure to use smaller elements in the region of high stress to reduce this problem, and/or insert the Command ERESX,NO into the model to copy instead of extrapolate stress to the corner nodes.