COMSOL Forums: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/
Most recent forum messagesThu, 15 Nov 2012 15:08:56 +0000COMSOL Forums: Total Mass of a Structurehttp://www.comsol.com/shared/images/logos/comsol_logo.gif
http://www.comsol.com/community/forums/general/thread/32991/
Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90512
Thank you all very much.<br />
<br />
I am able to proceed. <br />
<br />
JMThu, 15 Nov 2012 15:08:56 +000032991.1352992136.90512Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90439
Hi<br />
<br />
You are right that a point mass is not part of the integration, as you integrate over a specific "Entity" domain or boundary times distance, or edge times area, so you need to add by yourself the extra masses you have attached on points, edges ...<br />
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Take care also for the eigenfrequency and the body laod cases, these do neither not include the extra mass. If you have a point mass attached to a domain and you apply a domain load (gravity load), you need also to add the point force corresponding to the added point mass.<br />
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This can seem cumbersome, but it is applying the strict way of one physics per domain, or another per boundary, or per edge ... and these are separate and must all be updated.<br />
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Just the same way if you add 2 or more physics, you must ensure that the BC are given for EACH physics and completely, symmetry boundaries for "solid" might NOT be also symmetry boundaries for Temperature etc<br />
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--<br />
Good luck<br />
IvarThu, 15 Nov 2012 06:03:54 +000032991.1352959434.90439Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90426
For beams you can do a line integral to get the area and multiply that manually by density and cross-sectional area or include these quantities in the integral. The area is typically called beam.area and the density is beam.rho.<br />
<br />
Nagi Elabbasi<br />
Veryst EngineeringWed, 14 Nov 2012 21:30:00 +000032991.1352928600.90426Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90420
Thanks again,<br />
<br />
Also if I add a point mass or a boundary mass I don't think integrating over the volume with rho will give me the mass of the entire system. That's is alright because I can add the added mass to the result of the integral to have the entire mass of the system. The question still remains if I only have edge elements how do I find the mass of the system?<br />
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Thanks,<br />
<br />
JMWed, 14 Nov 2012 20:03:28 +000032991.1352923408.90420Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90418
Thanks,<br />
<br />
My next question is how to accomplish this in the Beam module where every component is defined using edge elements. There aren't any domains, how can I find the mass in this situation?<br />
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Thanks,<br />
<br />
JMWed, 14 Nov 2012 19:40:23 +000032991.1352922023.90418Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90411
Hi <br />
<br />
if you compute the volume you are assuming the density is a constant, this might be correct, <br />
<br />
but its easier to integrate, over all (or the relevant) Domains, the density "material.rho" this gives you the true total mass, even with several differet materials, as COMSOL will map the different densities of the different domains correctly<br />
<br />
--<br />
Good luck<br />
IvarWed, 14 Nov 2012 18:44:37 +000032991.1352918677.90411Re: Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90397
uh, can't you just compute the volume of the structure and multiply it times its density?Wed, 14 Nov 2012 17:15:28 +000032991.1352913328.90397Total Mass of a Structure
http://www.comsol.com/community/forums/general/thread/32991/#p90395
Hello,<br />
<br />
I was wondering how to extract the total mass of system. I have solids model of a beam and a beam model of a beam. I wanted to compare their total masses to each other.<br />
<br />
Any help would be greatly appreciated.<br />
<br />
Thanks,<br />
<br />
Joshua MendozaWed, 14 Nov 2012 16:37:56 +000032991.1352911076.90395