Modelling temperature as a stress field
Modelling temperature as a stress field
(OP)
Hi, I am new to Abaqus I would appreciate if the experts here could give me some simple advices.
Basically I am trying to simulate the stress rate when the model is cooled from 100C to 23C.The cooling rate is 2C/min.
Since the model is cooled uniformly , I do not need any heat transfer analysis. My first approach was to set predefined field in initial step to 100 and in Step 1(static,general) I set the predefined field to 23. This however doesn't seem to be correct as from my understanding abaqus only takes the property of the material at 100C and 23C respectively and for my case the elastic modulus and CTE is temperature dependent.
Can anyone here guide me to the proper approach?
Thanks!!
Basically I am trying to simulate the stress rate when the model is cooled from 100C to 23C.The cooling rate is 2C/min.
Since the model is cooled uniformly , I do not need any heat transfer analysis. My first approach was to set predefined field in initial step to 100 and in Step 1(static,general) I set the predefined field to 23. This however doesn't seem to be correct as from my understanding abaqus only takes the property of the material at 100C and 23C respectively and for my case the elastic modulus and CTE is temperature dependent.
Can anyone here guide me to the proper approach?
Thanks!!





RE: Modelling temperature as a stress field
Rob Stupplebeen
RE: Modelling temperature as a stress field
I can't see how time comes into this unless you have strain rate data, and to be honest 2C/min doesn't sound like it would cause a problem. Of course if you have uniform temperatures then you won't get any stresses unless you have restraints that oppose the expansion/contraction.
Hoping to say Tata
RE: Modelling temperature as a stress field
My problem here is because the elastic modulus and CTE is temperature dependent.. let's say its not linear.. but Abaqus only deals with temperature A and temperature B... meaning that anything between A and B is ignored.. This is verified when I entered all kinds of crazy values in between 100C and 23C.. and the results are the same with the model that only have values of 100C and 23C.
Therefore, i am thinking that setting predefined field is not the correct way?
RE: Modelling temperature as a stress field
Rob Stupplebeen
RE: Modelling temperature as a stress field
I am not sure if you set the the predefined field of initial step at 100C and then set the predefined field as 23C in step 1, will this represents thermal cooling? If that is the case is there anyway to simulate cooling rate?
This is because I don't want instantaneous cooling(point A to point B in 1sec) as the elastic modulus and CTE is temperature dependent, in fact it is not linear and I personally think that cooling rate plays some role in it?
RE: Modelling temperature as a stress field
God call. Step 1 100C step 2 23C.
Rob Stupplebeen
RE: Modelling temperature as a stress field
Are there any other ways to set the temperature instead of setting it in predefined field?
This forum is superb:) I shall contribute bk my knowledge once Im an abaqus expert :P
RE: Modelling temperature as a stress field
To set the temperatures, you could run a separate thermal analysis and just fix the temperatures to vary by some amplitude over the time interval. Then read the odb file in for your stress analysis
Hoping to say Tata
RE: Modelling temperature as a stress field
Sorry but how do i run a thermal analysis? I only have the Elastic modules , CTE , starting and final temperature.
If i'm not wrong Heat transfer analysis will require me to specify the density, specific capacity and conductivity?
Thanks!!
RE: Modelling temperature as a stress field
For a thermal analysis choose heat transfer, transient as the step. You'll also have to change your element type too.
Hoping to say Tata
RE: Modelling temperature as a stress field
Let's say its 100C to 23C with -2C/min cooling rate, what will the amplitude be and where can I set this in the step?
Again I can't stress how greatful am I for all your help.
RE: Modelling temperature as a stress field
Hoping to say Tata
RE: Modelling temperature as a stress field
In your post are you using heat trasfer analysis or static general? This is because in the heat-trasfer analysis there is no temperature to set in the load module (only Surface heat flux , body heat flux and concentrated heat flux)?
As for the interaction module, all of them are for surface contact whereelse I just need to perform uniform cooling in the entire model?
I see that you have replied in another post of mine. If I am not wrong doesn't time dependent Elastic modulus affect the strain rate therefore it is consider as strain rate dependent material properties?
Many thanks!!!
RE: Modelling temperature as a stress field
In the other post (which I can't find now) I'm sure you said you had temperature dependent properties, and not time dependent properties. If somehow you have a time dependent elastic modulus then at each discrete time step you will have constant temperatures and therefore a constnat/uniform elastic modulus. How will this give you any stresses?
Hoping to say Tata