WOLFRAM SYSTEMMODELER

LineForceWithTwoMasses

General line force component with two optional point masses on the connection line

Wolfram Language

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Click for copyable input
SystemModel["Modelica.Mechanics.MultiBody.Forces.LineForceWithTwoMasses"]
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Information

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

This component is used to exert a line force between the origin of frame_a and the origin of frame_b by attaching components of the 1-dimensional translational mechanical library of Modelica (Modelica.Mechanics.Translational) between the two flange connectors flange_a and flange_b. Optionally, there are two point masses on the line connecting the origin of frame_a and the origin of frame_b. These point masses approximate the masses of the force element. The locations of the two point masses are defined by their (fixed) distances of L_a relative to frame_a and of L_b relative to frame_b, respectively.

In example MultiBody.Examples.Elementary.LineForceWithTwoMasses the usage of this line force element is shown and is compared with an alternative implementation using a MultiBody.Joints.Assemblies.JointUPS component. The composition diagram of this example is displayed in the figure below.

The animation view at time = 0 is shown in the next figure. The system on the left side in the front is the animation with the LineForceWithTwoMasses component whereas the system on the right side in the back is the animation with the JointUPS component. Both implementations yield the same result. However, the implementation with the LineForceWithTwoMasses component is simpler.

In the translational library there is the implicit assumption that forces of components that have only one flange connector act with opposite sign on the bearings of the component. This assumption is also used in the LineForceWithTwoMasses component: If a connection is present to only one of the flange connectors, then the force in this flange connector acts implicitly with opposite sign also in the other flange connector.

Connectors (4)

frame_a

Type: Frame_a

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

frame_b

Type: Frame_b

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

flange_b

Type: Flange_a

Description: 1-dim. translational flange (connect force of Translational library between flange_a and flange_b)

flange_a

Type: Flange_b

Description: 1-dim. translational flange (connect force of Translational library between flange_a and flange_b)

Parameters (12)

animate

Value: true

Type: Boolean

Description: = true, if animation shall be enabled

animateMasses

Value: true

Type: Boolean

Description: = true, if point masses shall be visualized provided animate=true and m_a, m_b > 0

m_a

Value: 0

Type: Mass (kg)

Description: Mass of point mass a on the connection line between the origin of frame_a and the origin of frame_b

m_b

Value: 0

Type: Mass (kg)

Description: Mass of point mass b on the connection line between the origin of frame_a and the origin of frame_b

L_a

Value: 0

Type: Position (m)

Description: Distance between point mass a and frame_a (positive, if in direction of frame_b)

L_b

Value: L_a

Type: Position (m)

Description: Distance between point mass b and frame_b (positive, if in direction of frame_a)

cylinderLength_a

Value: 2 * L_a

Type: Length (m)

Description: Length of cylinder at frame_a

cylinderLength_b

Value: 2 * L_b

Type: Length (m)

Description: Length of cylinder at frame_b

s_small

Value: 1.E-10

Type: Position (m)

Description: Prevent zero-division if distance between frame_a and frame_b is zero

fixedRotationAtFrame_a

Value: false

Type: Boolean

Description: =true, if rotation frame_a.R is fixed (to directly connect line forces)

fixedRotationAtFrame_b

Value: false

Type: Boolean

Description: =true, if rotation frame_b.R is fixed (to directly connect line forces)

animateMasses2

Value: world.enableAnimation and animate and animateMasses and m_a > 0 and m_b > 0

Type: Boolean

Description:

Components (5)

world

Type: World

Description:

cylinder_a

Type: Shape

Description:

cylinder_b

Type: Shape

Description:

sphere_a

Type: Shape

Description:

sphere_b

Type: Shape

Description:

Used in Examples (1)

LineForceWithTwoMasses

Demonstrate line force with two point masses using a JointUPS and alternatively a LineForceWithTwoMasses component