Rotational Spring for Flexible support

fernandezpelayo

I am doing a lecture about FE modal-update. The case is a cantilever beam with a flexible support. I would like to know if there is an option to introduce a rotational spring to relax the fixed support condition on beam rotation DOF.

I have seen the axial spring as element but exists the option for roration DOFs

Thanks in advantate.

Victor

No, sorry. You would have to build one from translational springs. Either make a moment arm with another beam element or, perhaps more elegantly, use a constraint equation to couple the rotational DOF of the beam element to the translational DOF of a spring.

fernandezpelayo

Ok, thanks. Althought the easiest option would be the rotational spring, a simple trick is to reduce the section or the material (young's modulus) of the base of the cantilever beam, i.e. with a new component with one element of small size.

disla

I faced this issue recently.
Check this option in case you need to maintain the support point with fixed coordinates.
It allows to adjust the rotational stiffness.

fernandezpelayo

Thanks. Finally I did with equations and it works perfetly.

disla

Hi fernandezpelayo

Do you mean by custom model definition or new constrain equation.
¿Would you share your trick?

fernandezpelayo

Hi, disla, I attach the file I have used.