Remote Displacement

The remote displacement condition is used to guide the displacement of a face or edge of a structure from a remote point. There are several advantages compared to a classical displacement boundary condition. When the deformation behavior is set to deformable, the application of the remote displacement boundary condition doesn’t add any stiffness to the associated entity. Also with the remote displacement a rotation can be applied to an edge or a face of a structure.

There are also some limitations, mainly the fact that this is a linear boundary condition and valid only if small displacements and rotations occur in the area of the applied entity and the remote point itself.

Translation

The user defines for each of the translational directions if the displacement should either be unconstrained or predescribed. Each predescribed value can either be defined by a scalar value, a function or a table. For function or table data the value may depend on time (or frequency in case of a harmonic analysis) and the spatial coordinates.

Rotation

For each rotational direction the rotation can either be prescribed or unconstrained. In case of a predescribed rotation the value is given in radians. The input methods and possible dependencies are the same as for the translational directions.

Remote Point

Here the user defines the coordinates of the external point on which the displacement is applied. The coordinates are given in the global coordinate system of the mesh.

Deformation behavior

This property defines if the applied associated entities (edges or faces) may deform or if they are assumed to be rigid.

If the setting deformable is selected, no additional stiffness is generated on the applied entities. The remote point is connected to the entities by a RBE3-constraint.

If the setting undeformable is selected the entity behaves like a rigid part. The connection of the point and the entities is a multi-point constraint which blocks all relative displacements between the affected nodes.

Hint

If the deformable option is used and the number of nodes of the assigned entities is large (>1000), it is advised to use either the MUMPS or PETSC solver instead of Multfront since the performance of Multfront is not optimal for this kind of equations.

Example

Comparison of fixed value and remote displacement boundary conditions on a beam bending test (beam dimensions 1 m * 0.1 m * 0.01 m):

Von Mises stress (top) and total displacement (bottom) contour plot on the deformed shape with a fixed value displacement boundary condition of 0.05m applied to a square of 0.1m width

Von Mises stress (top) and total displacement (bottom) contour plot on the deformed shape with a remote displacement of 0.05 m at the center of the beam applied to a square of 0.1m width