Rope
Massless Rope component
The Rope component models a massless element that always remain straight between the points of connection. The Rope component has options for compliance and for connecting to a Pulley or Winch component.
Usage
Parameters
Connections
The Rope component can be used separately as a rigid or flexible two-force element or together with a Pulley component or Winch component. The Rope component can be used in series to transfer force along a given path.
Material Flow Sign Convention
If the Boolean parameters Fixed end a and/or Fixed end b are set to false (unchecked), 1D translational flanges are added to enable material flow.
Basic
The initial length of a rope component is determined from the position of the multibody frames to which it is connected. Make sure the rope's multibody frames are connected to other elements with defined positions. See the example below.
Ropes in Series
If the Boolean parameters Fixed end a and/or Fixed end b are set to false (unchecked), 1-D translational flanges are added to enable material flow.
Ropes and a Pulley
Before connecting a Rope to a Pulley or Winch on end a (frame_a) and/or on end b (frame_b), the boolean parameters Pulley on end a and/or Pulley on end b must be set to true (checked), respectively. When set to true (checked) the selections are indicated on the Rope icon with an orange circle and the corresponding multibody frame is turned to a 2-vector port.
Formulation
Name
Condition
Default
Description
Modelica ID
Extensible
Pulley on end a=false∧Pulley on end b=false
true
When checked (true) the rope becomes extensible. The axial rigidity is a function of the unstretched length. Note: The rope is extensible when used with or a Pulley or Winch.
extensible
No force in compression
Extensible = true
false
When checked (true) the rope applies no force in compression. This option may be avoided if the rope always remains in tension.
noCompression
Properties
Units
EA
cond
1000000
N
Axial rigidity: Modulus of elasticity (E) times area (A)
Use damping ratio
When checked (true), damping is defined as a fraction of stiffness
useDampingRatio
dr
cond∧Use damping ratio=true
0.01
Damping ratio: c=dr⁢EA
c
1
N⁢sm
Linear damping coefficient
Unstretched length
When checked (true) the unstretched length is given by a parameter independent of the initial length of the rope
useLength
L0
cond∧Unstretched Length=true∧Pretension=false
m
Pretension
cond∧Unstretched length=false
When checked (true) the unstretched length is given by the initial length of the rope minus the pretension length.
usePretension
δL
cond∧Pretension=true∧Unstretched length=false
0.1
Pretension length
dL
cond=Extensible=true∨Pulley on end a=true∨Pulley on end b=true
Pulley on end a
When checked (true) the rope is to be connected to a pulley at frame_a
toPulley_a
Pulley on end b
When checked (true) the rope is to be connected to a pulley at frame_b
toPulley_b
Fixed end a
Pulley on end a=false
When checked (true) the rope is fixed to frame_a. When unchecked (false) a 1D mechanical flange is enabled for material flow.
fixed_a
Fixed end b
Pulley on end b=false
When checked (true) the rope is fixed to frame_b. When unchecked (false) a 1D mechanical flange is enabled for material flow.
fixed_b
Visualization
Show visualization
showVisualization
Transparent
Show visualization=true
transparent
radius
0.02
Rope radius. This radius is only used for the cylindrical visualization of the rope
Color mode
Single color
Choose color option: (1) Single color, (2) Two colors: Tension and No tension, (3) Multi-color: Color based on tension value
colorMode
Rope color
Show visualization=true∧Color mode=2
gray
Rope color 1
color
2nd rope color
Show visualization=true∧Color mode∈2,3
red
Rope color 2
color2
τmin
Show visualization=true∧Color mode=3
0
Minimum Tension: color 1
minTension
τmax
1000
Maximum Tension: color 2
maxTension
Force arrows
When checked (true), arrows are added at end points to visualize tension.
show Tension
Scale
Tension visualization=true
Force scale (N to m)
tensionscale
Color
blue
Force arrow color
tensioncolor
Force arrow transparency
tensiontransparent
Flow rate arrow
Fixed end a=false∨Fixed end b=false∨Pulley on end a=true∨Pulley on end b=true
When checked (true), an arrow is added to visualize material flow speed and direction
showFlow
Fixed end a=false∨Fixed end b=false∨Pulley on end a=true∨Pulley on end b=true∧Flow visualization=true
Speed scale (m/s to m)
speedscale
magenta
Flow arrow color
flowcolor
Flow arrow transparency
flowtransparent
Summary Variables
Force unit
Unit in which the summary variable summary_Tension is expressed
forceUnitSummary
framea
End a multibody frame
frame_a
frameb
End b multibody frame
frame_b
frameap
Pulley on end a=true
End a a 2-Vector multibody frame For use with a Pulley or Winch component.
frame_ap
framebp
Pulley on end b=true
End b a 2-Vector multibody frame For use with a Pulley or Winch component.
frame_bp
flangea
Fixed end a=false∨Pulley on end a=true
End a 1D translational flange for rope flow.
flange_a
flangeb
Fixed end b=false∨Pulley on end b=true
End b 1D translational flange for rope flow.
flange_b
See Also
Pulley
Winch
Winch3D
Cable
Chain
Ropes and Pulleys Library Overview
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