reffer to superelement formulation it will help you, where you can define the sttiffnes of other structure and consider it in the simulation of one component. this ensures less CPU time, less Preprocesing work and other important factors. This should give you same result as you where simulation many components at the same time. Hope this helps.

Dear Tamer Qaimari,

thank you very much for you answer!

It is a nice idea, but not what I am actually looking for, because after I achieve this I will expand the model with parts which have time varying stiffness due to transformations.

Thank you again for the idea though.

i would like to understand the meaning of expand the model with parts which have time varying stiffness due to transformations? i did not get what you are trying to say?Please give example

Okay,

at first I want to run a co-simulation with two different models, both in Abaqus/Standard under static loads.

Afterwards, I want to add UMAT subroutines for specific parts of each model to simulate the non-linear response of the materials. Due to the implementation of the UMAT subroutine (which accounts for phase transformations of the material) the stiffness of some parts is varying depending on the developed stresses.

The last step would be to include UEL subroutines thus I referred to time varying stiffness.

okay i got you!. Connecting parts should be not a problem. what type of connection you have?

spot welding?

bolts with pretention?

regarding time varing stiffnes it is relaxation test?

Connection is very simple. Contact between two rigid parts and tie of a surface on another rigid part. The point is that the pairs of the contact are in different Abaqus models.

No, the stiffness varies due to phase transformation in the material.

I doubt that this is possible in Abaqus. 

You may need to think about co-executions option in Abaqus to sort this out.