As shown in the figure below, the problem has two parts: Part 2 goes throughout the part 1, creating a contact between two surfaces (highlighted in yellow). Both parts are 3-D solids. When an eccentric load, F in the figure, is applied on Part 2, the body tends to translate as well as rotate.
For solution, I am suppose to constrain the translation degrees of freedom but free the rotational degrees on contact surfaces. I tried using tie-constrain, but that doesn't allow rotation of Part 2, thus doesn't yield precise results. How can I solve this problem?
to perform a finite element analysis your model needs to be constrained so that rigid body motions (translations and rotations) are not allowed (otherwise the structure stiffness matrix is singular). Please note, however, that the rotation due to load eccentricity would not produce any stress in your structure
Denis Benasciutti can you please advice, how can I constrain translation and free rotation between two surface. Assume that some kind of load, say torque, rotates the Part 2 in the above model.
simply make your CAD model a one single part, so that at contact surfaces you have common nodes. By doing this, your FE model will be a single part with no rotation and translation lalowed. The FE analysis will find the shearing stress in the cylindrical part due to the eccentric load (although you can compute it very easily by the well-known Coulomb equation for torsion of cylindrical sections)
Can't you simply constrain one point somewhere on the base of your cylinder 2 and disallow translation along the x-direction?
Martin Baeker , translation doesn't seem that problematic. But, how can I free the rotational degrees in contact? I have updated the simplified model. Please see the picture attached.
Sorry, I don't understand - if it is true contact, rotation should possible. Of course you must not tie the surfaces and you must specify some contact model other than "rough".
nothing has changed from the original layout: you still have a rigid body motion (rotation) which is not allowed in a FE analysis
I would suggest except of proper contact conditions to add a soft torsional spring in the center of cylinder base.
You can not use tie or any constraint.
you need to use frictional contact. it is easy task in Abaqus.
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