PARAM, UNSYMSLV

Bulk Data Entry Controls the inclusion or exclusion of non-symmetric terms in the tangent stiffness matrix due to friction in frictional contact problems.

Parameter Values Description
UNSYMSLV <YES, NO>
YES (Default)
The non-symmetric terms in the tangent stiffness matrix due to friction are included in the frictional contact solution.
NO
The non-symmetric terms in the tangent stiffness matrix due to friction are excluded from the frictional contact solution.

Comment

  1. The non-symmetric terms represent the non-self-adjoint nature of friction, that is, if the corresponding normal pressure is increased, then the friction also increases, however vice-versa is not true.
  2. This parameter should be used with caution, as excluding the non-symmetric terms may lead to poor convergence of contact problems with friction.
  3. The unsymmetric solver is automatically turned on when effective follower loads are applied. If PARAM,UNSYMSLV,YES/NO is specified, the corresponding setting is respected even if follower loads are applied in the input deck (unless other features request the unsymmetric solver).