Hello there,

Here's the deal, I'm just starting from the basics and I am having two problems concerning temperature. The first is to define the alpha (temperature coefficient) when the material selected is the 21(User Defined), I just can't edit it, I am sending an image attached to illustrate.

The second is the most important. An one side fixed pipe with only temperature difference, no pipe density, no fluid density, no local forces or uniform loads. Therefore, an linear expansion should happen. I am just using T1 and the New Job Ambient Temperature. I wish to calculate DX, but my result is always zero. I am sending a image with my classic piping input.

Thanks a lot!

In your first figure above, that "expansion coefficient field" is "Read Only", so you're correct, you can't change this. If you want to enter an expansion coefficient, put it directly in the temperature field.

(Any value entered in a temperature field that is less than the "alpha tolerance" [defined in the Configuration] will be interpreted as an expansion coefficient in units of length per length.)

That "Read Only" field is for information only, to show what the coefficient is that corresponds to the temperature entered.

In your second figure, what was "ambient"?

The ambient temperature was 50 celsius.

I am a little bit lost here. So I enter the alpha in the temperature field right? Then does Caesar use the temperature value in any calculation, like the displacements? I mean, it's still not clear why my displacement is always null, when using only temperature effects. Anyways, thanks a lot for the answer.

There is a value defined in the Configuration (Alpha_Tolerance), which defaults to 0.05. In the temperature fields, any value defined less than this Alpha_Tolerance is assumed to be an expansion coefficient in units of length/length.

As an example, say you enter 0.02 in the T1 field. CAESAR II assumes this is a strain (expansion coefficient) value of 0.02 in/in (or mm/mm depending on your units). If you however enter 200 in the T2 field, CAESAR II assumes this is a temperature and the Error Checker looks up the corresponding strain (expansion coefficient) value and substitutes that in the analysis.

When you include T1 or T2 in your load case, you are applying the strain on each of the elements.

Ok,I understood. But, can I have displacement only applying T1? I mean, according to the help guide, T2 is the maximum temperature which my pipe will work. Therefore, only T1 and the New Job Ambient Temperature should give me a result.

CAESAR II doesn't interpret any of the Tx values to represent any particular operating scenario. You can put temperatures or expansion coefficients in any of the 9 temperature fields.

I am sorry for my insistence but it's still not clear for me. Why my displacement is still zero?

Look at your load case you have in your second screen. You are looking at the weight results.
If you want to see that thermal deflection, you must analyze T1 or whatever temperature set you wish to review.
Is there someone you can talk to about basic CAESAR II operation?

Thanks a lot Dave. Now I am facing another problem. My displacement value is always equal to my expansion coefficient (alpha) times my length. Usually the thermal free expansion is given by alpha*Length*(T2- T1), but it appears that Caesar II does not take the temperature in consideration.

If you manually specify an expansion coefficient, the units are "length/length" - it is assumed that this value already considers the difference between your T2 and T1.

Ok then I understood. But now I have another doubt, how can I set the temperature difference without specifying the expansion coefficient. Also, as far I am concerned the temperature difference should be between the New Job Joint Temperature and one of the 3 temperatures to be set, am I right?

The value for "ambient" (the base line) is set on the "Special Execution Options" dialog. Let's assume you set that to 21C.

In the Tx fields, you set your Operating temperatures. Let's assume you set T1 to 121. Then, the "delta T" for "Temperature Vector 1" is "121-21 = 100C".

CAESAR II will look up the expansion coefficient (interpolating at 121C), since the material database contains expansion coefficients at specified temperatures from the baseline (assumed to be 21C).

Alternatively, as I stated above, you can circumvent all this and specify directly the expansion coefficient for you specific temperature in units of length/length.