Since you're using elastic material in this test, try FORM=0 in *CONTROL_SPH.  Set ITHK=1 in *CONTROL_SPH as well so that the radius of the particles are considered in the contact treatment.  Include *DATABASE_RCFORC will write histories of contact forces to rcforc; plot these forces to see if contact forces are being produced.  Set SOFT=1 in the *CONTACT input.
You are navigating away from the AIS Discovery experience