Assembly questions in Simscape Multibody about multibody systems with mixed rigid and flexible bodies

Hello，

I am creating a multibody dynamic mechanical system with a mixture of rigid and flexible bodies on Simscape Multibody, but according to my calculations, the assembly coordinate parameters should be accurate, but I found that the model was not assembled incorrectly, showing that my model was assembled. I have a consideration because the flexible body will be deformed under the tension and compression of the connected frame, so this coordinate cannot be accurately represented, so I want to ask how to solve such a problem?

I would appreciate it if I could get an answer accordingly.

Answer 1

[Steve Miller]

Hi - your model is expecting the system to assemble with the flexible bodies in an undeformed state. If your kinematic loops (closed chains of bodies and joints) cannot assemble properly unless the flexible bodies start in a deformed state, your model will not assemble.

Your system will need enough degrees of freedom so that the assembly can assemble even if the flexible bodies are not deformed. You can use prescribed motion to bend the parts into the deformed position, and then save the final state of that model, and start new simulations from there.

--Steve

[馨]

Hi，Steve

I think I might have understood what you're talking about。But i used the Flexible Rectangular Beam，how do I do that like you said？ Are there any cases of this? Do i need to use the method of reduced-order model?

--LinXin

[Steve Miller]

All flexible beams will start a simulation in an undeformed state. Your mechanism must assemble under those conditions. Once it has assembled, you can force it into the correct position. You can try saving the final state and restarting the simulation from there using settings under model Configuration Parameters, Data Import/Export pane.

https://www.mathworks.com/help/releases/R2022b/simulink/gui/initial-state.html

--Steve

[馨]

Thanks, Steve

I have known what is your mean. I will try it, and hoping this question are going to be solved very well.

LinXin