piston exercise objectives: the purpose of this exercise it to make the user familiar with the...
Post on 19-Dec-2015
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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
Piston Exercise
Piston.sldasm
Piston Model Exercise*Make ENGINEBLOCK ground* *Make all other parts moving*
PARTS SHOULD BE DEFINED AS FOLLOWS:
Piston Model ExerciseDefine Revolute Joint for Crankshaft to Ground
Piston Model ExerciseDefine Revolute Joint for Crankshaft to Conrod
1 2
3
Piston Model ExerciseDefine Inline JPrim Joint for Piston to Conrod
1 2
3 4
Piston Model ExerciseDefine Translational Joint for Piston to Engine Block
1 2
3
Piston Model ExerciseDefine 360 Deg/sec Rotary Motion on Crankshaft Revolute
Piston Model ExerciseRun the Simulation (using defaults)
Joint Definition - MotionDepending 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:ConstantStepHarmonicSplineExpression
Joint Definition - Motion with Step Function
-1.00 -0.70 -0.40 -0.10 0.20 0.50 0.80 1.10 1.40 1.70 2.00
Time (s)
-22.50
0.00
22.50
45.00
67.50
90.00
112.50
Dis
plac
emen
t (d
eg)
Joint Definition - Motion with Harmonic Function
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
Time (s)
-67.50
-45.00
-22.50
0.00
22.50
45.00
67.50
Dis
pla
cem
en
t (d
eg
)
Joint Definition - Motion with Harmonic Function
With a 0.25-sec time offset only or with a 90 degree phase offset (same result)
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
Time (s)
-33.75
-22.50
-11.25
0.00
11.25
22.50
33.75
Dis
plac
emen
t (d
eg)
Harmonic function with 22.5º average offset (same amount as amplitude)
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
Time (s)
-11.25
0.00
11.25
22.50
33.75
45.00
56.25
Dis
pla
cem
en
t (d
eg
)
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.
-20
0
20
40
60
80
100
0 1 2 3 4
Overshoot
0
20
40
60
80
100
0 1 2 3 4
Data Points
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.
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.
Plotting Results in SolidWorks
Plotting Results in SolidWorksMotion 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.