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Multiple Spherical Joint

Multiple Spherical Joint

Multiple Spherical Joint

(OP)
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.

RE: Multiple Spherical Joint

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

RE: Multiple Spherical Joint

(OP)
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!

RE: Multiple Spherical Joint

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

Best regards
Alexandru Dadalau

MESHPARTS GmbH
Tuning Your Simulation
http://www.meshparts.de

RE: Multiple Spherical Joint

(OP)
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.

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