Cylinder
Cylindrical rigid body
Description
Connections
Parameters
Equations
Examples
The Cylinder component models a homogeneous cylindrical rigid body along a given axis with a predefined density. Based on the properties, i.e., axial unit vector, length, radius, and density, the center of mass, total mass, and moments of inertia are calculated for this rigid body.
Name
Modelica ID
frame__a
Coordinate on one end of the cylinder axis
frame_a
frame__b
Coordinate on the other end of the cylinder axis
frame_b
frame__cn
An array of additional frames on the cylinder axis
frame_c[n]
Default
Units
e__axis
1,0,0
Axial unit vector
e_axis
L
1
m
Cylinder length
R
0.1
Cylinder radius
R__i
0
Cylinder inner radius
R_i
Select density
User defined
Select a predefined material density
selectDensity
ρ
1000
kgm3
Cylinder user-defined material density
customDensity
Use additional frames
false
True means additional frames can be added
addFrames
L__add
L2
Each value in this array defines a frame on the cylinder axis w.r.t. frame_a
L_add[:]
Use initial conditions
True means parameters for specifying initial conditions for frame_a are enabled. Refer to: Rigid Body
useICs
Show visualization
true
True means the cylinder geometry is visible in the 3-D playback
visualization
Transparent
True means the geometry is transparent in the 3-D playback
transparent
Color
Cylinder color in the 3-D playback
color
The two end frames of the cylinder have the same orientation. The translation vectors L e__axis and L2 e__axis w.r.t. frame_a define the frame_b and the center of mass frame, respectively. Cylinder mass is calculated as
m=ρ π⋅R2−R__i2 L
where the cylinder material density, ρ, can be defined using the "Select density" parameter. This parameter lets the user either enter a value or select among predefined material densities.
Figure 1: Different options for the "Select density" property
Assuming the default direction of 1,0,0 for the cylinder axis, the moments of inertia expressed from the center of mass frame are
I__xx=12 m⋅R2+R__i2
I__yy=112 m⋅3R2+R__i2+L2
I__zz=I__yy
The right-hand side of these equations will interchange if another axial unit vector is specified.
Swinging T-Shaped Object
Figure 2 shows the layout of a MapleSim model that uses two Cylinder components to simulate a freely swinging T-shaped object. Note how the frame_b of the vertical cylinder (axis = [0,1,0]) is connected to the frame_c of the horizontal cylinder (axis=[1,0,0]) to form the T-shaped object. For the horizontal cylinder, frame_c is located halfway L__add=L2 between frame_a and frame_b. A snapshot of the 3-D playback is shown in Figure 3.
Figure 2: Model layout
Figure 3: 3-D playback snapshot
Slider-Crank Mechanism
In the following example, four Cylinder components are connected with revolute and prismatic joints, as shown in Figure 5, to model a slider-crank mechanism. Using Cylinder components facilitates the modeling by automatically calculating mass and moments of inertia and also results in realistic visualization in the 3-D playback window, as shown in Figure 6.
Figure 5: Model layout
Figure 6: 3-D playback snapshot
See Also
Machine Elements
Multibody
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