Fixed Displacement Condition¶

The fixed-displacement (or clamped) boundary condition pins the displacement to zero on the boundary \(\Gamma\):

This is a homogeneous Dirichlet condition on all three displacement components. It removes the rigid-body modes of the model. You must apply it on at least one boundary so the static problem is well-posed.

When to use this¶

• Clamped supports of cantilever beams, brackets, and lugs welded or bolted to a stiff structure.
• Foundation contacts modelled as rigid (slab anchors, pier bases).
• Symmetry planes where symmetry sets the in-plane displacement — although a partial / direction-specific Dirichlet is generally more appropriate (not currently exposed; use a small marker patch if you need it).
• Gauge fix for an otherwise pure-traction problem (the static equations have a six-dimensional rigid-body null space that you must pin somewhere).

Usage¶

from mufem.structural import FixedDisplacementBoundaryCondition

clamped_bc = FixedDisplacementBoundaryCondition(
    name="Clamped",
    marker="Beam::Clamped" @ Bnd,
)

structural_model.add_condition(clamped_bc)