Enabling 6DoF substructured matrices

[WhyNamWin]

Hello,

I'm trying to export the reduced mass and stiffness matrices to use them in multibody simulations by the substructure method. I use C3D8 elements to build the FE model but these elements only have 3DoFs/node. As recommended, I have attached rigid body with 6DoFs (constraint rigid body+tie and setting small mass) to the interface nodes and apply the reduction on these ones. However, the output matrices still miss the rotational degrees of freedom. In the attach files, you will find a figure of the beam with the reference nodes located at the interface nodes. The .inp file is also provided but once compiled, the output matrices in .mtx files miss the rotational rows (they are filled with zeros).

Do you know how to fill the reduced matrices with the rotational degrees of freedom? (so that these rows are non-zero which is compulsory for multibody simulations)


Thanks in advance for any help,

[P.S.: I'm forced to use elements with 3 degrees of freedom per node, here this is just a small example]

 

[FEA way]

Which software do you want to use for MBD simulation ? In Abaqus you can generate a flexible body from substructure and export it in format accepted by Adams, Simpack and other programs. Just use the following keyword: *FLEXIBLE BODY, TYPE=... and then run the translator (if you want to use Adams, Simpack or AVL Excite): abq adams/tosimpack/toexcite job=...

 

[WhyNamWin]

Thank you for your answer !

I will definitely test the import to Adams using what you recommend.

Do you have any example file or web link to a full example ?

Thanks