Any expert in sequentaily coupled analysis

[Newuser2006]

i have tried many times to get answers for what is happening with me but no one seems to know till now.i have done a normal heat transfer analysis.then i started a new static simulation and defined the results of the previous analysis as a temperature field.
1-the heat distribution at the beginning and at the end of the second simulation is not like the results of the first simulation
2-i have tried to run the second simulation without defining the temperature field,and i got the same results for strain,stresses...that means that the temperature field was not playing any role,knowing that my material is temperature dependent.
please any ideas suggestions,and dont speak so profesional that i wouldnt be able to understan what do you mean.

 

[bassmanjax]

Hi Newuser2006

As Corus stated in the previous thread, and I agree with him;

http://www.eng-tips.com/viewthread.cfm?qid=156056&page=2

I think that you will have to do the second step as a coupled thermal-stress analysis, even though the start conditions are carried over from the first step. If you don't do your forming op as a coupled analysis, then the temperatures won't be carried through and have any effect(as you have observed).

I don't see why you cannot do this as two steps in a single analysis run?

Regards

Martin

 

[Newuser2006]

first thanks much bassmanjax,
when i make a heat transfer step,iam not allowed or it does not give me the option of doing a static step in the second one.I cant also make as a coupled sim.since this process is an experiment where the peace will be heated up then the forming will start.have you got my point.so ihave to define the results of the first analysis in the second one without getting dummy warnings like node 112342 is not active in the instance and initial conditions will be taken.
so who can help also.suggestions!!

 

[corus]

It sounds like you haven't got the same mesh for the static analysis as you had for the thermal analysis. It's best to go back to the thermal model, redefine the step to static, alter all your boundary conditions for displacements etc. and alter the element type to a stress element. I don't think you have to remesh it and then the nodes should be the same. I hope that wasn't too professional sounding.

corus

 

[bassmanjax]

Newuser

Just to add to what Corus said, make sure that you are using coupled temperature-displacement elements in both meshes, otherwise the temperature DOF won't be available.

BTW, I assume that you've looked at sections 6.5.3 and 6.5.4 in the ABAQUS Analysis manual - 6.5.3 deals with sequentially coupled thermal-stress analysis.

Regards

Martin

 

[corus]

bassmanjax,
I think he/she isn't using a coupled temperature-displacement model but is running a thermal analysis first, saving the temperatures, and then reading them as loads for a static analysis. You therefore don't use the same element in both meshes but use a thermal element, such as DCD8R and then read the temperatures into a second model that has CD8R elements. If a coupled temperature displacement model had been used then there would have only been one input deck, one mesh, two kinds of loads (thermal/mechanical) in each step. In this case there appears to be no need to run such a coupled temperature-displacement model.

corus