Author Topic: stretch rod with point mass  (Read 4805 times)

unimetal

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stretch rod with point mass
« on: April 01, 2021, 01:30:55 PM »
Hi,

I created a stretch rod with the truss function and would like to assign a point mass to the first and the last node.
What is the best/easiest way to do this?

Thanks in advance for your help!

Prof. R.L. Taylor

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Re: stretch rod with point mass
« Reply #1 on: April 01, 2021, 02:08:56 PM »
Check manual, Chapter 8 in current user manual.  There is section on nodal mass, dampers, stiffness.

unimetal

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Re: stretch rod with point mass
« Reply #2 on: April 02, 2021, 06:22:13 AM »
Dear Professor Taylor,

thank you very much. I used an old manual where this chapter was missing.
Is there any way to plot the masses to see if I have used the command correctly?

There should be a Mass of 80 units (for Example kg) at node-Nr. 1 and a Mass of 90 units at node-Nr. 1001
 
MASS               
  1    0  80

MASS               
  1001  0  90
« Last Edit: April 02, 2021, 06:28:09 AM by unimetal »

Prof. R.L. Taylor

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Re: stretch rod with point mass
« Reply #3 on: April 02, 2021, 07:26:42 AM »
No plot, look in output file to see.  Note mass is by dof, so you only have mass on dof 1

unimetal

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Re: stretch rod with point mass
« Reply #4 on: April 02, 2021, 07:56:06 AM »
Dear Professor Taylor,

[...]Note mass is by dof, so you only have mass on dof 1

if I only assign the mass to the 1st degree of freedom, then, for example, does the inertia only work in the 1st degree of freedom and not in the 2nd degree of freedom?
In my case the mass doesn't move in the direction of the 2nd degree of freedom. So the 2nd dof should not be considered, right?
Otherwise it should look like this:

MASS               
  1    0  80 80

MASS               
  1001  0  90 90

note: I'm an absolute beginner in FEAP. Thank you for your note with the output file.
« Last Edit: April 02, 2021, 07:57:45 AM by unimetal »

Prof. S. Govindjee

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Re: stretch rod with point mass
« Reply #5 on: April 02, 2021, 10:02:46 AM »
If at the top of the file you one have one dof, then you will only need to define mass in that direction.  If your definition at the top of the file shows d dofs then you should define a mass in all d direction.