You are probably better off asking this question in the SimCenter forum.
However... in regard to NX Nastran, the approach depends on whether a linear or non-linear analysis.
In both cases you need to make sure your relevant material(s) have an expansion coefficient.
For Linear analysis, the material has a reference temp, and then you would apply temperatures to relevant nodes, and thermal strain is calculated using the difference between the material reference temp and the applied nodal loads. Note that you should also set an active "default temperature", which means that all nodes in the model which don't have a nodal temp load will otherwise adopt that default temp.
For nonlinear analysis, you will need a separate load set which includes the Initial Temps - and this would be set as an Initial Condition in your non-linear analysis setup. Then your subsequent load set(s)/case(s) needs to include the different subsequent temps on the relevant nodes. Again, note that you will get analysis errors if any nodes do not have a temperature applied either in the Initial Condition or the subsequent load case(s). This is most easily resolved in each case using an Active Default Temp which uses that value for any nodes where no temp has been specifically set.
All this assumes you know the temps to set - if you don't you will first need to run a thermal analysis to calculate the temps. And keep in mind that unresisted thermal strain produces zero/negligible stresses. Similarly if the thermal strain is "undifferentiated" (everything expands together with no differential strain between connected parts), then the result will produce displacements/strain but zero/negligible stresses.