Rod - MapleSim Help

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Rod

Massless flexible rod

Description

Connections

Parameters

Equations

Examples

Description

The Rod component models a massless flexible rod. Rod can be seen as a spring/damper connection between two end frames with a given unstretched length and spring/damping constants.

Connections

Name

Description

Modelica ID

frame__a

Frame on one end of the rod

frame_a

frame__b

Frame on the other end of the rod

frame_b

Parameters

Name

Default

Units

Description

Modelica ID

L__0

1

m

Unstretched length of the rod

L0

K__s

1e 6

Nm

Spring constant

Kspring

K__d

1e 4

N⋅sm

Damping constant

Kdamper

Show visualization

true

-

True means the disk geometry is visible in the 3-D playback

visualization

r

0.01

m

Rod radius used for visualization only

r

Color

-

Rod color in the 3-D playback

color

Transparent

false

-

True means the geometry is transparent in the 3-D playback

transparent

See Also

Machine Elements

Multibody

 

 

Equations

Examples

Equations

Assuming that the translation vector, r, is directed from frame_a, X1,Y1,Z1, to frame_b, X2,Y2,Z2, the resultant forces of the rod are

f1=fr⋅r⋅eX1⋅eX1+r⋅eY1⋅eY1+r⋅eZ1⋅eZ1

f2=−fr⋅r⋅eX2⋅eX2+r⋅eY2⋅eY2+r⋅eZ2⋅eZ2

where e denotes unit vectors and f__1 and f__2 are the reaction forces applied to frame_a and frame_b, respectively, and

f={K__d ⅆⅆt⁢L +K__sL−L0    L≠00L=0

where L=r is the instantaneous rod length. Note that in these equations, bold non-italic symbols denote vectors. Figure 1 shows the rod and the end frames.

Figure 1: Rod and end frames

 

Examples

Pendulum

You can use the Rod component, as shown in Figure 2, to model a pendulum with flexible connecting rod, swinging in 3-D space. You may want to define a specific initial condition for the end mass as well as the spring and damping constants of the Rod. Two visualization components are used to enhance the 3-D playback.

Figure 2: Model layout

 

Figure 3: 3-D playback snapshot

 

Slider-Crank Mechanism

In this example, a Rod, a Disk, and two Cylinders components are connected to revolute and prismatic joints, as shown in Figure 4, to model a slider-crank mechanism. This model is similar to the one discussed in the Linkage and Box help pages with the difference of using a Rod component to connect the crank to the slider.

Figure 4: Model layout

Figure 5: 3-D playback snapshot