Forces

Use the Forces tool to create forces and to edit the orientation and properties of forces.

Create Forces using the Forces Tool

A force entity, as the name suggests, is used to apply a force and/or a torque on a body or between two bodies.

  1. From the Model Browser, select the system to which the Force entity is to be added.
  2. Right-click on a system in the Model Browser and select Add > Force Entity > Force from the context menu.
    OR
    Right-click on a force folder in the Model Browser and select Add Force from the context menu.
    OR
    From the Model ribbon, click the Forces icon .
    The Forces guide bar is displayed.
  3. Select whether to create a single force or a force pair, by selecting the Create Pair check box.
    A force entity, like most of the entities that are created in MotionView, can be a single entity or a pair entity. Pair entities help in creating models which have symmetric properties.
  4. Select whether to create an Action Only or an Action Reaction Force, through the Action Only Force check box.
    An action only force acts on a single body on which force is applied. An action reaction force acts on two bodies; one is called the action body and the other the reaction body. The force on the reaction body is equal and opposite to that on the action body.
  5. Select the Type of force from the drop-down menu.
    The following choices are available for Action Only and Action Reaction Force:
    Table 1. Force Reference Table
    Type Subtype Define Force Description
    Action Only Translational On bodies/Use markers Force on a body along three directions.
    Rotational On bodies/Use markers Torque on a body about three directions.
    TransRotational On bodies/Use markers Force and Torque on a body along/about three directions.
    Scalar Force along Z axis of Ref frame On Bodies Force on a body along Z axis of a reference frame. (Marker)
    Scalar Force about Z axis of Ref frame On Bodies Torque on a body about Z axis of a reference frame.
    Action Reaction Translational On bodies/Use markers Force between two bodies along three directions.
    Rotational On bodies/Use markers Torque between two bodies about three directions.
    TransRotational On bodies/Use markers Force and Torque between two bodies along/about three directions.
    Line of Action Translation On Bodies Translation force along the line formed by two points of application between action and reaction bodies.
    Single Component Rotation On Bodies Torque about direction on action and reaction bodies.
  6. Specify how to define force (On Bodies or Use Markers). Force between Markers is only available for Translational, Rotational, and TransRotational Forces.
  7. Select the first body reference (Body 1 or Marker I).
    • Select a body (or a marker) in the modeling window.

      OR

    • On the guide bar, click the Advanced Selector and make your selection in the Model Tree.
  8. Select the second body reference (Body 2 or Marker J). *Only in the case of Action-Reaction Force.
    • Select a body (or a marker) in the modeling window.

      OR

    • On the guide bar, click the Advanced Selector and make your selection in the Model Tree.
  9. Select an Origin (On Bodies only). In the case of Line of Action force, select the first point (Point 1) where the action force is applied on Body 1.
    • Select a point in the modeling window.

      OR

    • On the guide bar, click the Advanced Selector and make your selection in the Model Tree.
    • For Line of Action Reaction force, select a second point (Point 2) where the reaction force is applied on Body 2.
  10. Select a Reference Marker. *Not applicable for Line of Action and Single Component Rotational.
    • Select a marker in the modeling window.

      OR

    • On the guide bar, click the Advanced Selector and make your selection in the Model Tree.
  11. Optional: Click to reset the entity selections and select new entities.
  12. Once the reference selections are made, create the Force using one of the following methods:
    1. Click on the guide bar.

      OR

    2. Click the button that appears at the mouse location in the modeling window.

      OR

    3. Click to create the entity and start adding another entity.
    Once the Force has been added to the model, the corresponding Force will automatically be displayed in the browser area.

Edit Forces

  1. Edit the connectivity using the Forces tool:
    The bodies, origin, and reference marker of a force can be edited using the Forces tool.
    1. Select the Force to be edited either through the modeling window or the Model Browser.
    2. Click on the Forces tool icon in the Model ribbon.
      A guide bar for the force appears.
    3. Activate the Body, Point or Marker collectors in the guide bar that need editing.
    4. Pick a different body, point or marker either from the modeling window or the Advanced Selector .
  2. Using the Entity Editor:
    All properties of the Force can be edited from the Entity Editor.
    1. Select the Force to be edited either through the modeling window or the Model Browser.
      The Force Entity Editor is automatically displayed.
    The Entity Editor displays the following properties that can be edited.
    Table 2. Force Properties
    Property Description
    General
    Label Descriptive label for the entity.
    Varname Variable name of the entity.
    ID Integer identifier.
    Active Active state of the entity (True or False). Entity is deactivated if False.
    Type Select the type of Force – Action only or Action reaction.
    Subtype Based on the type of force, select a subtype. Refer to the Force Reference table.
    Define Force Select the method for defining force, either through bodies or markers.
    Action force on Select the body or marker on which the force is applied as action.
    Reaction force on Select the body or marker on which the force is reacting. *Available only when force type is Action Reaction.
    Properties
    Trans/Rot Properties For each direction, select a type of input and corresponding set of references and values.
    Linear Indicates a constant value of force.
    Value A real value (or a reference data member of type real value).
    Curve Indicates force input using a curve.
    Curve Select a 2D cartesian or parametric curve.
    Interpolation Interpolation scheme to be used for the curve – AKIMA, CUBIC, LINEAR or QUINTIC.
    Independent variable Solver expression to consider as the independent variable for the curve.
    Spline 3D Indicates force input using a 3D spline.
    Spline3D (value) Select a Spline3D entity.
    Interpolation Interpolation scheme to be used for the curve – AKIMA, CUBIC, LINEAR or QUINTIC.
    Independent variable X Solver expression to consider as the first independent variable (X) for the Spline3D.
    Independent variable Z Solver expression to consider as the second independent variable (Z) for the Spline3D.
    Expression Indicates force input using a solver expression.
    Expression Solver expression that describes the motion.
    User defined This is an alternate to the Type choices. Force can be defined using a user subroutine.
    User expr
    Use local file and function name (Optional) Provide a local file and function for the sub-routine.
    Local file Select a file for the subroutine based on Function type.
    Function type Select the type of file: DLL, Python, MATLAB or Compose.
    Function name Name of the function within the subroutine file that needs to be called.
    Note: If local file and filename is not used, the solver will use the subroutine based on its default search criteria. Refer to the solver reference guide to learn more.
    Appearance
    Visible Control the visibility of the entity icon.
    Note & Tags
    Note Optional descriptive note.
    Attachment Candidates Add tags for the entity as possible candidate for attachments to Systems/Assemblies/Analyses.