Bulk Data Entry Automatically constrain degrees-of-freedom with no stiffness.

Parameter Values Description
YES (Default)
The global stiffness matrix is checked for degrees-of-freedom (DOF) with no stiffness. If found, these DOF are automatically constrained.
The DOF with no stiffness are not automatically constrained.


  1. PARAM, AUTOSPC is generally applicable only to grid points (with unconstrained DOF) attached to structural elements.
  2. Rotational DOFs of grid points connected only to solid elements are constrained by AUTOSPC by default. If you turn AUTOSPC off, OptiStruct will still remove rotational DOFs. Therefore, in either case, OptiStruct automatically handles the rotational DOFs of solid elements.
  3. Free grid points are also automatically constrained in the pre-processor and are not affected by PARAM, AUTOSPC.
  4. The list of grids with degrees of freedom that were constrained by the second round of AUTOSPC is output to the .HM.comp.tcl file.
  5. The SPCOFF and SPCOFF1 Bulk Data Entries can be used to exclude degrees-of-freedom from AUTOSPC.