Much Better than a Fixed Support!
I don't know why I didn't think of it before, but the best set of constraints for this problem are these three:
That way, there is no artificial stress caused by a Fixed Support.
To answer your question, when you create a new Stress result, the default is all bodies, but you just pick the body you want. Notice how the extremes on the color legend adjust for just that one body.
Auto Time Stepping
You turn that on when the solver doesn't converge on its own. Otherwise, you can leave it Program Controlled.
Elasto-Plastic Material Model
Plasticity is one of the Material Models in Engineering Data. There are many types. The simplest is Bilinear Kinematic Plasticity. That only requires a Yield Strength and a Tangent Modulus. Perfectly plastic means the Tangent Modulus = 0.
Look at these graphs.
Mohr-Coulomb Material Model
After I deleted the Fixed Support and used the three single axis displacement constraints, the material failure error in the solve.out file did not occur. I suspect that this error occurs when a material model is written assuming that the material will never see tensile stress, because the model becomes undefined in tension, and during the solve, a tensile stress is calculated, the solver has to stop with an error.