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Thermal Expansion Analysis

Thermal Expansion Analysis

Are there any software packages out there that do a decent job of predicting deformation or complex shapes due to thermal effects?  

The parts I want to analyze will be castings, so material is uniform.  I am looking to minimize the angular distortion of mounting points, so as to maintain overall mechanical accuracy when the part is subjected to a moderate, uniform temperature rise.

Better still, would be the ability to assign a temperature gradient, and determine how the shape changes.

This must be similar to what designers of machine tools do...but I can not find a software package that describes this capability.  Perhaps I am not using the right search terms, or talking to the right people.     

RE: Thermal Expansion Analysis

You'd need FE software to do that unless the shape was simple enough to perform hand calculations.


RE: Thermal Expansion Analysis

Yes of course...I know that...but what FEA.  That is what I am looking for.  I have not been able to find one that will predict deformation as a result of an applied thermal profile.  

RE: Thermal Expansion Analysis

I was reviewing NEI Nastran NEIWorks 2.1, and I see they introduced a thermal stress/deflection feature in their most recent release.   

RE: Thermal Expansion Analysis

I'm going to show my ignorance.

Uniform material at uniform temperature does not expand uniformly?

(2B)+(2B)'  ?

RE: Thermal Expansion Analysis

.. or are we talking about a temperuatre gradient within the part?

(2B)+(2B)'  ?

RE: Thermal Expansion Analysis

Complex closed loop parts, in my experience, do not hold their shape perfectly, even under uniform temperature rise.  Think about a complex casing, with ribs, shells, etc.  

Of course, in the real world, the temperature is never uniform, so a proper analysis would indeed assume a gradient, or custom temperature mapping....

RE: Thermal Expansion Analysis

Surely any general purpose FE package would be able to do this?  Certainly Strand7 can.

Doug Jenkins
Interactive Design Services

RE: Thermal Expansion Analysis

With ribs etc. that would locally be cooler, you'd need a program that calculated the temperature profile and then calculated the deflection. Most FE packages can do this.


RE: Thermal Expansion Analysis


Complex closed loop parts, in my experience, do not hold their shape perfectly, even under uniform temperature rise.  Think about a complex casing, with ribs, shells, etc.  
Is this a result of residual stresses from forming the part?


(2B)+(2B)'  ?

RE: Thermal Expansion Analysis


Yes, theoretically, an unconstrained component which is made of a single homogeneous isotropic material and subject to a uniform temperature change should expand / contract uniformly. However, many (most? all?) "real world" scenarios break at least one of those assumptions:

Unconstrained? Probably not - the part is probably attached to something or is sitting on something (most things are!), which may locally constrain its thermal expansion / contraction.

Single homogeneous isotropic material - OK, many components would approximate to this condition

Uniform temperature rise or fall? Probably not - many heating / cooling scenarios will produce some sort of thermal gradient ( a hot side and a cold side), and / or the attachment to another component can act like a "heat sink" leading to local thermal gradients.

As soon as you have thermal gradients, you have a non-trivial condition, and thermal analysis (including possibly FEA) may be warranted.


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