Cooling stage simulation of two bodies in contact 3

[Lodham]

Hi everybody,

I would like to model the cooling operation of two bodies sticked together and with two distincts expansion coefficient.
I would like to observe the stress concentration appearing due to the difference in terms of expansion coefficient.
I have some difficulties to build the case in terms of Boundary conditions and interaction properties.

- Boundary conditions:
There is an initial T° of 150°C for the two bodies.
And two plane of symetries.
I do not have to define here any B.C. for the surrouding air which is at 25°C?

- Interaction properties:
In addition to the definition of the two surfaces in contact, I have to define some interaction properties for the free surfaces !?
Is it the film condition option?
What represents exactly the "film coefficient" ?
What do I use for the skin T°? the 150°C of the initial T° or the T° of the surrounding air?
Finally, I have no idea of the value of conductance I should use between the two surfaces (materials are Silicon and epoxy).

Any help would be extremely useful

Thanks
Pierre

 

[corus]

My guess is that this is a thermal transient problem and as such you'll need density and specific heat, as well as thermal conductance for the materials. For the thermal BCs you'll need to define heat loss to the ambient air, usually by natural convection and radiation. In addition you'd have to define gap conductance and gap radiation between the two bodies. If the two bodies have different thermal expansion you may need to use a coupled temperature displacement model. Check which elements these are. Define restraints/loads on the bodies as well as thermal boundary conditions for this type of model.

The manager

 

[Lodham]

Thank you for your answer Corus,

I will use the Temp-Displ analysis.
I just need to find physical values for gap conductance properties between Silicon and Epoxy. Such data are always difficult to find in the literature!

When the two bodies are in contact, there is no real gap between them. Can I only define the gap conductance for a null value of gap?

I don't think radiation will have an important impact on such a computation.

Thanks again
Pierre

 

[corus]

If there is no gap you could just tie the nodal tenperatures together. This would be equivalent to setting a high value of gap conductance for a zero gap.

 

[Lodham]

Another question:
How do I define the heat loss to the ambient air?
Is this in the boundary conditions, load?

thanks again

 

[Lodham]

Another question:
How do I define the heat loss to the ambient air?
Is this in the boundary conditions, load?

thanks again

 

[corus]

Heat loss to the air is normally by natural convexction and radiation, defined in the interaction module. For physical constants you'd have to refer to text books such as McAdama.

 

[Lodham]

Thanks a lot Corus for your very valuable help

 

[emadomrani]

I have another question.
I am beginner about ABAQUS. I have the same problem and I dont know if method is true or not?

My Method:

I define a initial temperature in LOAD->Predefined for initial step and then I define final temperature in LOAD->BC for created STEP(coupled Temp-Displacement)

please help me
Best regard