Piston Exercise

1
Piston Exercise

• Objectives
• The purpose of this exercise it to make the user
  familiar with the process for manually defining
  constraints on assemblies.
• This exercise will cover revolute, translational,
  inline, and driving motions.
• Load the Piston assembly file

2
Piston Exercise
Piston.sldasm
3
Piston Model Exercise
Make ENGINEBLOCK ground
Make all other parts moving
PARTS SHOULD BE DEFINED AS FOLLOWS
4
Piston Model Exercise
Define Revolute Joint for Crankshaft to Ground
5
Piston Model Exercise
Define Revolute Joint for Crankshaft to Conrod
2
1
3
6
Piston Model Exercise
Define Inline JPrim Joint for Piston to Conrod
2
1
3
4
7
Piston Model Exercise
Define Translational Joint for Piston to Engine
Block
2
1
3
8
Piston Model Exercise
Define 360 Deg/sec Rotary Motion on Crankshaft
Revolute
9
Piston Model Exercise
Run the Simulation (using defaults)
10
Joint Definition - Motion
Depending on the joint type, you can control
different freedoms Can control the
displacement, velocity, or acceleration of a
joint You can select from Input
Functions Constant Step Harmonic Spline Expr
ession
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Joint Definition - Motion with Step Function
112.50
90.00
67.50
Displacement (deg)
45.00
22.50
0.00
-22.50
-1.00
-0.70
-0.40
-0.10
0.20
0.50
0.80
1.10
1.40
1.70
2.00
Time (s)
12
Joint Definition - Motion with Harmonic Function
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Joint Definition - Motion with Harmonic Function
With a 0.25-sec time offset only or with a 90
degree phase offset (same result)
Harmonic function with 22.5º average offset
(same amount as amplitude)
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Joint Definition - Motion with Data Points
As you cannot have any instantaneous sharp
transitions on motion generators, two
spline-fitting options are available to smooth
out the data. This will have little effect on
smooth transitioning functions but will change
behavior on functions like that shown below.
The Data ID allows the user to store several data
point functions and select the one they wish to
edit or use for a specific motion generator.
15
Plotting Results in SolidWorks
Inter Plot Options are available by right
clicking on a motion entity. The pop-up menu is
entity sensitive so will only show relevant plot
options.
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Plotting Results in SolidWorks
Motion Entities can also be dragged directly onto
the plot branch. Then the user can select the
result and component they wish to
display. Note that Results with a CM at the
front are for the Center of Mass location and all
other results on parts are measured at the Part
Reference Frame origin. Joint Results for Force
are in the global coordinate system. All joint
displacement, velocity, and accelerations are in
the joint coordinate system.