I have been told about "Spin Softening" option for rotating cylinders in Ansys but did not really understand how/what/why. I have gone thru Ansys documentation and it appears that the centrifugal loads are applied to the deformed configuration if the Spin Softening option is selected. Does Abaqus have a similar option ?
Now what the "Spin Softening" is meant to do is apply a centrifugal force:
F(r) = density*(r+u)*speed^2
where u is the radial deformation. Most classical equations ignore this and assume that the force is applied only on the undeformed configuration.
My question now is, are there any closed-form equations for the displacements/stresses in a rotating disk that include this "Spin Softening".
Any comments/opinions about this Spin Softening option in Ansys and how it relates to any such functionality in Abaqus will be appreciated. Thank You.
Re: Spin softening
Abaqus appears to approach the problem in a different way. The manual says " It is assumed that the model (or that part of it to which these [centrifugal] forces
are applied) is described in a coordinate system that is rotating with
an angular velocity ...". The details, for Abaqus v 6.5-1, are in Section 6.1.1 "Centrifugal, Coriolis, and rotary acceleration forces".
For analytical solutions for a disk (in the nonlinear elastic context), see Problem 5.2.6 and Problem 5.3.7 of "Nonlinear Elastic Deformations" by Ray Ogden. Once you know the strain energy function you can calculate the stresses and the principal stretches.
-- Biswajit
Finite deformations in a rotating frame
There are several nice descriptions of how this works. (1) is one of the original papers by Oden and Lin 1986 (CMAME) [but beware they forgot about objectivity in the material formualtion for their viscoelastic model] (2) is a nice paper by LeTallec and Rahier 1994 (IJNME). Attached is a short report we wrote on the matter a while back. This, modulo, some implementation issues is how the formulations and computations work.
http://www.ce.berkeley.edu/~sanjay/ucb_semm_1998_02.pdf
Prof. Dr. Sanjay Govindjee
University of California, Berkeley
Dr. Govindjee, Thank
Dr. Govindjee,
Thank you very much for the report.
Srihari