Varying ambient conditions

[MNS747]

Hi all
I am doing heat transfer analysis on a machine tool spindle and i want to model effect of varying environmental conditions on it. for e.g. during the day temperature changes from 22C to 25C where as during night it goes from 25C to 23C. I was wondering what is the best way of modelling it. Am confused either to use user subroutines(which I havent got any idea which one to use) or abaqus interaction module (film condition). Also do any one know how do abaqus workout this i.e. does abaqus calculates it using q=hAdt?
Any help regard to this would be greatly appreciated.

Regards

 

[amubashar]

Hi,

You can apply temperature as a temperature boundary condition on the exposed edges of the spindle. To change the temperature boundary condition, use a table and vary the values of temperature with time. The heat transfer in the spindle would be calculated using Fourier's law of heat conduction.

Regards

Aamir

 

[MNS747]

Hi Aamir.
Thankyou for your reply. As i got internal heating as well, temperature boundary conditions are only steping up/down the temperature where as i want it to be added into the current surface temperature due to internal heating and see the output. Temapreature boundary condition is varying the surface temperature excluding the internal heating effects and giving me square waves.
I am currently doing with surface film conditions (interaction module). Any other ideas would be greatly appreciated.

Regards

 

[amubashar]

Hi,

Unless I am missing something, the temperature boundary condition should not be excluding any temperature change due to internal heating. The only effect of temperature boundary condition is that the boundaries are considered to be raised to the specified temperature instantaneously. If you want to use the surface film condition, then its possible to change the sink temperature (theta not) over simulation time by creating an amplitude whereas theta is the temperature of a point on the surface.

Regards

Aamir

 

[MNS747]

Hi Aamir
Thank you for your reply. yes you are right about Temp BCs as they are only stepping up and down the surface temperatures. I used film conditions and trying to vary sink temperature. while doing that got confused about what dows sink temperature actually means. is it the desired destination temperature? I just cant get my head round to it and I will apprecaited if you please explain the sink temperature.

Regards

 

[amubashar]

Hi

May be you can have a look at the Cambridge university FAQ page for an example of film boundary condition. The web address is:

http://www-h.eng.cam.ac.uk/help/amb/programs/fe/faq55/abaqusf7.html

Regards

Aamir

 

[MNS747]

Thank you very much Aamir for your help and it is highly appreciated.

Regards