Thermal Stress Analysis

Hi,

I  am not familar with the transient analyis of thermal-mechanical coupled problems. But I guess the question now is concerning about how you specify the boundary conditons, right? Since you do not know the exact surface heat flux as an input, you can not define your "surface radiation" heat transfer...

What I will do:

1) specifiy the temperature rate 20C/min at surface, and check the surface heat flux as a function of time, say q_s(t);

2) release the first BCs and apply q_s(t) at the surface, then you probabilily will end up a rate close to the required value.

3) through this q_s(t), you probably will find a adequate trend to change the ambient temperature.

I just guess this will solve your problem.

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i am a civil engeenering

i want to modelling a arch dam in abaqus but i have many problems

please help me

i am new in abaqus

i want by program ( matlab ) have many coordinate nodes of geometry dam , but i dont konw use this nodes in abaqus

please help me

Dear all,

         I had one problem while solving the sequencial coupled thermal stress analysis of a disc brake. Can anyone help me the way of calculating the Dflux while solving it in abaqus? I am applying it directly on the disc without considering the pads? this i am applying while doing the thermal analysis? And also how can we applying mass flow rate with change of temp? Your help is highly appreciated?

Thanks

Jobin

I am modelling one part system. I have two materials on that part and i mesh the part as single using tetrahedral elements. 

I have a body heat flux and it seems i get continuous temperature and displacement profiles but my stresses are discontinuous where the two material join, i would expect that in case two very different young modulus but the ones i have are very similar.

As i am using a single mesh, considering they a bond, i dont need to use interaction or tie constraints.  

Has anybody experienced this situation? Any idea what could be the problem?

Thank you very much 

Hi Roxana,

The short answer is most probably you did nothing wrong. That's how most FE packages work. Read on for a bit of an explanation.

Most solid mechanics FE formulations have displacement as the primary variable. Similary for thermal analysis temperature is the primary variable. Now if only the primary variables (not their derivatives) are take to be continuous over elements, you will have a discontinuity in the derivatives even over a homogenous single material. So strains and temperature gradients would be discontinuous, as a result stresses and heat fluxes will be discontinuous too. FE packages do some sort of averaging for stresses on element boundaries or just plot contours based on results on quadrature points so one won't usually notice the discontinuity from post processing results. 

If you want stress continuity, you need to use an FE formulation where continuity is enforced on the displacement derivatives too.