Material units in Modal Simulation
Hello,
I have a problem when running a modal simulation. There is not error, but the number of eingenvalues found is zero. May be the problem is realed to the units. The mesh is in mm, and young modulus is MPa (N,mm), poisson is adimensional. My question is the next, which units shoud have rho, Tons/mm3 or Kg/mm^3?
Thanks, Jesus Sanz
Hi,
Zero eigenvalues usually correspond to rigid body motion. Do you apply any boundary conditions?
Regards Vladimir
On 27. 04. 23 13:29, J. Sanz wrote:
Hello,
I have a problem when running a modal simulation. There is not error, but the number of eingenvalues found is zero. May be the problem is realed to the units. The mesh is in mm, and young modulus is MPa (N,mm), poisson is adimensional. My question is the next, which units shoud have rho, Tons/mm3 or Kg/mm^3?
Thanks, Jesus Sanz
SfePy mailing list -- sfepy@python.org To unsubscribe send an email to sfepy-leave@python.org https://mail.python.org/mailman3/lists/sfepy.python.org/ Member address: vlukes@kme.zcu.cz
Hello, Yes, I apply fixation in a specific area. I tested a basic case, and It works fine, but the mesh was in meters. My case is in mm, so I think the issue is related to the units. Which unit would you use for the density if you are working with MPa (young modulus), and mm for the mesh? Thanks, Jesus
El jue, 27 abr 2023 a las 17:07, Vladimir Lukes (<vlukes@kme.zcu.cz>) escribió:
Hi,
Zero eigenvalues usually correspond to rigid body motion. Do you apply any boundary conditions?
Regards Vladimir
On 27. 04. 23 13:29, J. Sanz wrote:
Hello,
I have a problem when running a modal simulation. There is not error, but the number of eingenvalues found is zero. May be the problem is realed to the units. The mesh is in mm, and young modulus is MPa (N,mm), poisson is adimensional. My question is the next, which units shoud have rho, Tons/mm3 or Kg/mm^3?
Thanks, Jesus Sanz
SfePy mailing list -- sfepy@python.org To unsubscribe send an email to sfepy-leave@python.org https://mail.python.org/mailman3/lists/sfepy.python.org/ Member address: vlukes@kme.zcu.cz
SfePy mailing list -- sfepy@python.org To unsubscribe send an email to sfepy-leave@python.org https://mail.python.org/mailman3/lists/sfepy.python.org/ Member address: jsanz451@gmail.com
Hi Jesus,
the density should be tonne/mm3. Have a look at the attached table.
Regards Vladimir
On 27. 04. 23 18:36, J. Sanz wrote:
Hello, Yes, I apply fixation in a specific area. I tested a basic case, and It works fine, but the mesh was in meters. My case is in mm, so I think the issue is related to the units. Which unit would you use for the density if you are working with MPa (young modulus), and mm for the mesh? Thanks, Jesus
El jue, 27 abr 2023 a las 17:07, Vladimir Lukes (<vlukes@kme.zcu.cz <mailto:vlukes@kme.zcu.cz>>) escribió:
Hi, Zero eigenvalues usually correspond to rigid body motion. Do you apply any boundary conditions? Regards Vladimir On 27. 04. 23 13:29, J. Sanz wrote: > Hello, > > I have a problem when running a modal simulation. There is not error, but the number of eingenvalues found is zero. > May be the problem is realed to the units. The mesh is in mm, and young modulus is MPa (N,mm), poisson is adimensional. > My question is the next, which units shoud have rho, Tons/mm3 or Kg/mm^3? > > Thanks, > Jesus Sanz > _______________________________________________ > SfePy mailing list -- sfepy@python.org <mailto:sfepy@python.org> > To unsubscribe send an email to sfepy-leave@python.org <mailto:sfepy-leave@python.org> > https://mail.python.org/mailman3/lists/sfepy.python.org/ <https://mail.python.org/mailman3/lists/sfepy.python.org/> > Member address: vlukes@kme.zcu.cz <mailto:vlukes@kme.zcu.cz> _______________________________________________ SfePy mailing list -- sfepy@python.org <mailto:sfepy@python.org> To unsubscribe send an email to sfepy-leave@python.org <mailto:sfepy-leave@python.org> https://mail.python.org/mailman3/lists/sfepy.python.org/ <https://mail.python.org/mailman3/lists/sfepy.python.org/> Member address: jsanz451@gmail.com <mailto:jsanz451@gmail.com>
SfePy mailing list -- sfepy@python.org To unsubscribe send an email to sfepy-leave@python.org https://mail.python.org/mailman3/lists/sfepy.python.org/ Member address: vlukes@kme.zcu.cz
participants (2)
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J. Sanz -
Vladimir Lukes