Unexpected Reaction force results

https://www.simscale.com/workbench/?pid=5398130486588740399&mi=run%3A141%2Csimulation%3A125&mt=SIMULATION_RUN

Please refer - Sandwich simulation> quarter success> Run 10

Aim is to simulate displacement controlled compression test conducted on UTM and get the reaction loads. Quarter model is being used as memory not enough to run full model.


This is the displacement setting. Top face has been chosen to apply displacement.


This is the fixed support setting. Bottom plate has been chosen ( volume assignment)

I have used the volume calculation and the area calculation option in the result controls. Both are selected with option of “sum” and “reaction force”. The bottom plate which is fixed support is the entity being probed for both the above calculations. Whole partbody for the volume calculation and the lower face for the area calculation of reaction forces.


Area calculation settings


Volume calculation settings

As the top plate is given a displacement downwards and due to the physical contact settings some reaction force is expected from the bottom plate that should be acting in the positive Z direction. However the result i get is 0 throughout the simulation interval for both the volume and area calculation as shown below.

Is this happening because I have used the penalty method for physical contact which allows contact penetration because I can see penetration of the core into the top and bottom plates in the post-processor.

Currently am trying to use the augmented lagrange method for contact however convergence has been a struggle ( run 11 , 12 , 13 )

To conclude- why are my reaction forces zero ? How can I get better values of reaction?

1 Like

Hey there! I am running a couple of tests to check the case :slight_smile: I will be back shortly, but in the meantime, if you have any updates, feel free to share!

Best regards,
Fillia

1 Like

Hi there, I hope that you had a nice weekend!

Please check my Run 18 here, and let me know what you think: https://www.simscale.com/workbench/?pid=4599391677158078101&mi=run%3A154%2Csimulation%3A125&mt=SIMULATION_RUN

The changes are:

1.An automatic contact detection was added
2. The physical contacts were fixed
3. The fixed support boundary condition was only added to the bottom face, not the whole part.

Best regards,
Fillia

1 Like

Hey,
Yet to go through it completely, however just wanted to note that my intention is to have non-linear contact assignment at the areas that automatic contact detection is used. Which is why I had assigned physical contact to the core structure as well.
Do you feel this task is unachievable?
Shall get back as soon as I have a closer look at the set-up and understand what is going on?

Thank you
Marwan

1 Like

Hey,
Hope you are having a great day. So I have gone through your set-up(run18) and analysed the results. Comparing with my experimental results I have found that the reaction loads from analysis is 1/4th of what I require. To increase the reaction loads from analysis I have tried increasing the penalty coefficient in the physical contacts (waiting for results). Could you tell me what else could I possibly tweak in the set-up to increase the reaction loads obtained, without changing the material behaviour as this is a fixed parameter in the experiment?

Also could you tell me if I can still get a solution with physical contacts (non linear) in the interlocked core surfaces of the sandwich structure and if yes what areas should i improve to get closer to convergence because i have tried changes with mesh, contact types and parameters ( penalty coefficientetc) , simulation, numerics etc and still failed? This is the ultimate goal :grinning: :grinning:

Thanks a lot
Marwan

Great, thank you for such a matter.
Knowledge sharing