# Boundary Condition: Constraint

## Function:

Applies a clamped conditions or forced displacement.

## Application:

Point, Line, Surface.

## Description:

Each component of the displacement (along the global X, Y, and Z axes) can be clamped or forced (clamping is identical to forcing to zero).
For each component, select among the following options: None, Clamped, or Forced.
- None: No condition is applied along this component direction.
- Clamped: The displacement is blocked along this direction
- Forced: Enter values to define the Amplitude (A) and Phase (P) of the forcing function.

## Remarks:

- The amplitude (A) of the displacement is in meters. The phase (P) is in degrees.
- Only sinusoidal [A × sin (ω × t + P)] forcing functions (or clamping) are allowed. Transient and user-defined forcing functions are not yet implemented.

## Illustration:

## ATILA Equivalent:

- For a Clamped condition, the ATILA equivalent is a boundary condition (after the END command) in the format -N D 0, where N is the node number where the constraint is applied, and D is 1, 2, or 3 for the X, Y, and Z components of the constraint.
- For a Forced condition, the ATILA equivalent is an EXCITATION in the form N ELECPOT RE IM, where N is the node where number the constraint is applied, and RE = P × cos (P) and IM = P × sin (P) are the real and imaginary parts of the forcing function.

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