Add Spring FB

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Add Spring FB

Why add a Spring FB?

See also: Spring FB dialog

Use a Spring FB to add a force between two Points*. The Points* are usually in different Parts.

* Point, start-Point, end-Point, center-Point.

The Spring FB can superimpose these forces:

Spring Force - a force proportional to the dimensional difference between the Spring's Anchor-Point and its Free-Length.

Constant Force - a constant force that pulls or pushes the Spring's Anchor-Points, throughout the machine-cycle.

Coulomb Constant-Force - a constant force that acts in the opposite direction to the relative velocity between the Spring's Anchor-Point.

Drag-Force - a force that is proportional to the relative velocity between the Spring's Anchor-Points.

Drag Force-Squared - a force that is proportional to the square of the relative velocity between the Spring's Anchor-Points.

Force-Function - a force-function that you add to the input-connector

The Forces values are superimposed (added) to together to give the Total-Force at the output-connector.


Anchor-Points :

The two(2) Points that define the axis through which the Spring FB applies its Force.

You select the Points when you add a Spring FB.

Force element :

A Spring FB is a Force-Element.

Linear Motive Force :

The Spring FB can become a Power-Source. It indicates the Application Force that you must supply to drive the Kinematic-Chain.

A Linear Motor would provide the Linear-Force.

Add Spring FB

Spring FB in the graphic-area

Spring FB in the graphic-area

STEP 1:Start the Add Spring FB command


1.Click Add menu > Forces sub-menu  > Add Spring FB


1.Click Forces toolbar > Add Spring FB

STEP 2:Select the Anchor-Points

1.Click two different Points - the Anchor-Points - in two different Parts.

The distance between the two Points shows next to your mouse-pointer.

2.Click the graphic-area to place the dimension and the Spring FB.

The Spring FB is now in the graphic-area.

STEP 3:Open the Spring FB dialog

Spring FB in the graphic-area:

Symbol Red-14-1b

FB - see Spring FB connectors

Symbol Red-14-2

Spring between the anchor-points


Dimension between the anchor-points

Note: Positive (Negative) force values Pull (Push) the Anchor-Points together (apart).

Spring FB States:

The Spring FB can be in three different states.

STATE 1: The Spring FB is enabled.

The default state. The Spring FB exerts a Force that is defined by the parameters in the Spring FB dialog.

Spring FB - Enabled

Spring FB - Enabled

STATE 2: The Spring FB is not enabled.

To enable/disable the Spring FB

1.Edit the Spring FB to open the Spring FB dialog

In the Spring FB dialog

2.Select / deselect the Enable Check-box.

3.Click OK-tiny-11-15 to close the dialog.

Spring FB > Not enabled

Spring FB > Not enabled

STATE 3: The Spring FB is a Linear Motor

To change the Spring to a Linear-Motor

1.Open the Configure Power Source dialog of the kinematic-chain for which the Spring FB will be Linear-Motor.

In the Configure Power Source dialog:

2.Click the Motion-Dimension FB that applies the motion to the kinematic-chain

3.Click the Spring FB as the Power Source,

The Spring FB is now a Linear Motor.

4.Close the Configure Power Source dialog.

See - Configure Power Source

Spring FB > Linear Motor

Spring FB > Linear Motor