Displacements

Displacements are constraints that can be applied to a model to limit deflections in desired locations and directions. Use the Displacements toolon the Structure ribbon to apply displacement constraints.

A design space can have any shape or topology as long as it is a single solid volume. A part that is used as a design space should not be very detailed. To ensure the most freedom to generate a shape, you should use the simplest design space possible. The more fine details you have in the design space, the longer it will take to run the optimization.

Unlike shape controls, displacement constraints should only be applied to non–design spaces. While they can be used as the sole constraint for an optimization, we recommend using them alongside a stress constraint. They are represented as pyramids that appear orange when selected or blue otherwise.

A displacement constraint is applied at a particular point on the model. You can choose to limit displacement in one direction or in all directions, as shown in the images below. A displacement constraint in one direction can have an upper bound, lower bound, or both.

Enforced Displacements

Enforced displacements are used when you don't know the magnitude of a force applied to a part, but you do know how much the part displaces as a result of that force. The Apply Enforced Displacements tool is located on the Disps icon on the Structure ribbon.

Click to see a demonstration of Enforced Displacements.

Launch Enforced Displacement Demonstration


Editing Displacement Constraints

Double-click on a displacement constraint to enter editing mode. This opens a microdialog that allows you to:

Left-click on an empty space in the modeling window to exit editing mode. Right-click or press Esc to exit the tool entirely.

Why Are My Results Disconnected?

When you use displacement constraints, it is important to either apply them near all of the major loads or to use both stress constraints and displacement constraints together. As shown in the first two images below, if you apply a single displacement constraint of 2 mm at the tip of the foot peg, the results are biased to only account for that displacement constraint. The third image shows how the optimized result changes if a stress constraint with a factor of safety of 1.2 is added to the displacement constraint. The resulting shape can resist the stress applied while maintaining a total displacement of 2 mm at the foot peg.

apply a displacement constraint in all directions
  1. Click the Displacements tool on the Structure ribbon.
  2. Move your mouse over a non–design space in the modeling window and click on a point.  A displacement constraint in all directions, represented as a sphere, is created where you click.
  3. Click-and-drag the orange pyramid, or enter a value in the text field of the microdialog to change the magnitude of the displacement constraint.
  4. Right-click on an empty space or press the Esc key to exit the tool.
apply a displacement constraint in a single direction
  1. Click the Displacements tool on the Structure ribbon.
  2. Move your mouse over a non–design space in the modeling window and click on a point.  A displacement constraint in all directions, represented as a sphere, is created where you click.
  3. Click on the sphere in the microdialog to modify the type of displacement constraint.
  4. Click on the Constrain in One Direction icon in the drop-down list to apply the displacement constraint in a single direction.
  5. Two orange pyramids appear, each with a separate microdialog, to represent the upper and lower bounds for the displacement constraint.
  6. Click-and-drag an orange pyramid, or click the chevron button and enter a value in the text fields of the microdialog to change the magnitude of the upper or lower bound for the displacement constraint.
  7. If you only want an upper or lower bound, but not both, turn off the checkbox in the microdialog for the bound you want to remove.
  8. To change the direction of the displacement constraint:
    • Click the X, Y, or Z on the microdialog.
    • Click the rotate icon movetool for md on the microdialog, then click-and-drag the blue arrows on the rotate tool or enter a precise value in the text box.
    • Click the chevron button and manually enter the x, y, and z components of the direction vector.
    • Press the perpendicular button button to revert to the default direction.
  9. Right-click on an empty space or press the Esc key to exit the tool.
include a displacement constraint in a load case
  1. Right-click on a displacement constraint in the modeling window or in the Model Browser. The context menu appears.
  2. Choose the Include/Exclude from menu item. A checklist of all the available load cases appears.
  3. Select which load cases should include the displacement constraint. Check marks appear by all of the selected load cases.