Force acting between two frames, defined by 3 input signals and resolved in frame world, frame_a, frame_b or frame_resolve



This information is part of the Modelica Standard Library maintained by the Modelica Association.

The 3 signals of the force connector are interpreted as the x-, y- and z-coordinates of a force acting at the frame connector to which frame_b of this component is attached. Via parameter resolveInFrame it is defined, in which frame these coordinates shall be resolved:

world Resolve input force in world frame
frame_a Resolve input force in frame_a
frame_b Resolve input force in frame_b (= default)
frame_resolve Resolve input force in frame_resolve (frame_resolve must be connected)

If resolveInFrame = ResolveInFrameAB.frame_resolve, the force coordinates are with respect to the frame, that is connected to frame_resolve.

If force={100,0,0}, and for all parameters the default setting is used, then the interpretation is that a force of 100 N is acting along the positive x-axis of frame_b.

Note, the cut-torque in frame_b (frame_b.t) is always set to zero. Additionally, a force and torque acts on frame_a in such a way that the force and torque balance between frame_a and frame_b is fulfilled.

An example how to use this model is given in the following figure:

This leads to the following animation (the yellow cylinder characterizes the line between frame_a and frame_b of the Force component, i.e., the force acts with negative sign also on the opposite side of this cylinder, but for clarity this is not shown in the animation):

Parameters (3)


Value: true

Type: Boolean

Description: = true, if animation shall be enabled


Value: Modelica.Mechanics.MultiBody.Types.ResolveInFrameAB.frame_b

Type: ResolveInFrameAB

Description: Frame in which input force is resolved (1: world, 2: frame_a, 3: frame_b, 4: frame_resolve)


Value: world.defaultN_to_m

Type: Real (N/m)

Description: Force arrow scaling (length = force/N_to_m)

Inputs (5)


Default Value: world.defaultArrowDiameter

Type: Diameter (m)

Description: Diameter of force arrow


Default Value: forceDiameter

Type: Diameter (m)

Description: Diameter of line connecting frame_a and frame_b


Default Value: Modelica.Mechanics.MultiBody.Types.Defaults.ForceColor

Type: Color

Description: Color of force arrow


Default Value: Modelica.Mechanics.MultiBody.Types.Defaults.SensorColor

Type: Color

Description: Color of line connecting frame_a and frame_b


Default Value: world.defaultSpecularCoefficient

Type: SpecularCoefficient

Description: Reflection of ambient light (= 0: light is completely absorbed)

Connectors (4)


Type: Frame_a

Description: Coordinate system a fixed to the component with one cut-force and cut-torque


Type: Frame_b

Description: Coordinate system b fixed to the component with one cut-force and cut-torque


Type: Frame_resolve

Description: The input signals are optionally resolved in this frame


Type: RealInput[3]

Description: x-, y-, z-coordinates of force resolved in frame defined by resolveInFrame

Components (5)


Type: World


Type: Arrow


Type: Shape


Type: BasicForce


Type: ZeroPosition