Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
Set spatial derivatives to zero as boundary conditions
Posted Jul 20, 2016, 4:57 a.m. EDT Structural Mechanics Version 5.1 0 Replies
Please login with a confirmed email address before reporting spam
I am trying to model the prestressed eigenfrequencies of a rectangular cross section beam. I aim to "hold" the beam in three locations, so we can define 5 points along it at x=-l/2-l0, -l/2, 0, l/2 and l/2+l0. Where l0 is the length of the ends of the beam, and l is the length of the middle portion of the beam, and it is held at positions x=-l/2, 0 and l/2. Initially, I thought the "pinned" constraint would be sufficient for these three locations, however, the eigenfrequency solution is producing results I thought this boundary condition would eliminate.
Ideally, I wish to define u(x=-l/2,0,l/2)=0 (that's easy) but also that d^2u/dx^2(x=-l/2,0,l/2)=0, i.e. the second SPATIAL derivative of displacement is equal to zero. All of the available point constraints available to me can only set displacement or TIME derivates of displacement.
How can I set these three points spatial derivatives to be equal to zero?
Thank you in advance if you can offer me any suggestions.
Hello Jeremy Bourhill
Your Discussion has gone 30 days without a reply. If you still need help with COMSOL and have an on-subscription license, please visit our Support Center for help.
If you do not hold an on-subscription license, you may find an answer in another Discussion or in the Knowledge Base.