Can convection element be used in the thermo-mechanical modeling

[ws18]

Dear all,

According to FEAP Manual, "the convection element is used with thermal elements" to consider convection and radiation boundary conditions. When I use convection elements with 2D and 3D thermal elements, I have no problem.

However, when I use convection element with FEAP built-in Thermomechanical solid element (small deformation version), the convection boundary condition cannot be imposed anymore. I also tried to use this convection element with my user thermomechanical element (finite deformation), still, the convection boundary condition cannot be imposed. Can convection element be used in the coupled thermomechanical analysis directly? It is also very possible that I used the convection element incorrectly, I really appreciate that someone can point out the mistakes in my inputfile (attached).

Thank you in advance.

[Prof. S. Govindjee]

Have you tried remapping the convection element dof to dof 4?

[ws18]

Dear Prof.Govindjee,

Thank you very much for your reply. I also think the DOF mismatching can be the reason. Would you please guide me how to fix this problem? Do I need to revise the convection element function (convec#d.f)?

Warm regards,
Wenya

[Prof. S. Govindjee]

Two things to try (separately):

1.  Set the temperature dof globally

Code: [Select]

GLOBal
TEMPerature DOF 4

2.  Alternately map the 4th global dof to dof 1 for the convection element.

Code: [Select]

MATErial 2
CONVection,,2,4
...


[ws18]

Dear Prof. Govindjee,

Thank you so much for your help. I tried your suggestions. And in my code, the second method works.

If you have time, can you please explain a little bit about the meaning of parameters in command 'convection,,2,4'? I guess '4' represents thermal DOF, but what about '2'?

Regards,
Wenya

[Prof. S. Govindjee]

The 2 is the material set number (the default value is the material number). I would guess that if you used
convection,,,4 it would also work.  Note the material set number is the number that goes on the element cards; it allows
one to attach multiple materials to a single element.