Simscape Multibody Object Collisions

Dear Mathworks community,

I am trying to modify this simulation (https://se.mathworks.com/help/physmod/sm/ug/model-planet-orbit-due-to-gravity.html#bvc9scm-1) of the solar system using MATLAB R2020a Simulink Multibody so that when the planets collide they wouldnt undergo an elastic collision (but rather deform or mold into one planet).

I noticed there is a "Reduced Order Flexible Solid" but I am unsure of how to provide the Mass and Stiffness matrices. There are no examples on using this online (at least I can't find any).

Is there any documentation on exactly how to calculate these for a given un-coupled object such as a planet or a star?

Thank you for your help,

Best regards

Answer 1

[Steve Miller]

I think the best capability for you to use would be the ability to enable/disable joints. If you put a deactivated weld joint between your two planets and then activate it when they get close, you can model an inelastic collision.

If you want there to be some energy loss as the two planets collide, you can apply some position-based damping to the two planets.

For deformation, you could consider using the variable mass blocks. I don't think the flexible bodies are what you want, as those are elastic bodies and will store energy as they are deformed.

--Steve