Motion Study Troubleshooting
The following are frequently asked simulation questions and answers.
General Questions:
Q: Calculations
and animations run slowly on my PC. Is there a way to get fast, shaded
animation?
A: Yes. Try the following:
For new simulations, work in small steps.
Try to get the general model working without using some of the more advanced
features.
If you encounter problems, determine some
of the basic causes. Focus on the portion of the model that has the problem
by suppressing other motion entities.
Strike a balance between the number of frames
captured and the time to calculate the animation. The more
frames you have, the better, but the calculation time increases. Using
100-200 frames has insignificant overhead on most systems.
Motion Analysis- Specific Questions:
Q: The reaction forces in the joints that
are calculated are incorrect. What might I be doing wrong?
A: Check that you set the units and values
for your motion study properly. Also check that you set the density of
each of your components correctly. You can also check that you do not
have redundant
mates.
To check the density of a component:
Right-click the
component and select click Open
Part 
.
Click Tools,
Mass Properties while viewing the component (not
the assembly).
Incorrect settings of units or density can
significantly affect the reaction forces.
Q: How do I plot my results?
A: Use Motion Analysis
to produce
a plot. To export your data for use in an external program,
right-click the background of a plot and select Export
CSV.
If working with linkages, remove redundancies
to improve the accuracy of the force results.
Have a rough idea of the expected animation
and magnitude results. This helps validate simulation results for the
design.
When you have small time events, such as
collisions, run multiple simulations with variations in settings to verify
the solution. Use sufficiently small time steps to capture the motion.
Save a history of your designs. Create different
study tabs and use a nomenclature that is intuitive. You can always go
back to an earlier design if you encounter a problem.
You can use higher frame capture rates when
you clear Animate
during simulation in the Motion
Study Properties PropertyManager.
For motion studies that do include 3D
Contact, try modifying elastic properties if your simulation
does not perform as expected.