Multiple Spherical Joint

[iboby]

I would like to ask you about one of my problem which I am working on
it related to my M.Sc thesis.


I am simulating a cylinder or a rectangular prism attaching to 12
springs ( I applied LINK for the springs) and these springs are
attached to the body at four point (at each point there are 3 springs
in x,y,z direction ).

My questions are :

- How can I make the SOLID element ( cylinder or rectangular prism) a
constrain to behave as a rigid body.

- How can I define the multiple joints ( e.g spherical joint) at the connection points of the springs to the body in a way that 3 springs can rotate independently.
there are 12 springs which each 3-ones must be attached in one point to the body in x,y,z direction.

 

[meshparts]

Make the solid rigid: Simplest solution is to make the elasticity modulus 1000x bigger that it is.
Spherical joints: Solid elements have only translational DOF so if you attach beam/rods to single solid nodes, the joint will be spherical automatically.

Best regards
Alexandru Dadalau

MESHPARTS GmbH
Tuning Your Simulation

http://www.meshparts.de

 

[iboby]

Thank you very much Meshpats.
I am expecting that the result of natural frequencies (6 natural frequencies and their mode shapes match my MATLAB results.
So I would like to ask how can I attach each three links at one node in way that each to be able to rotates about the three coordinate axes independently like independent spherical joint. here is my model!

 

[meshparts]

Your model looks fine to me. Where is the problem?

Best regards
Alexandru Dadalau

MESHPARTS GmbH
Tuning Your Simulation

http://www.meshparts.de

 

[iboby]

Your advise was very useful and I simulate my model again according to that. I applied SOLID186 with very high YM and LINK 180 for the srings. The frequencies are : 1-437 [Hz], 2-437, 3-437, 4-719, 5-758, 6-795 and except for the forth and sixth the rest are identical to my MATLAB ones but I wonder my model is fully correct and I doubtful about the frequencies corresponding to rotation about the coordinate axis.