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Nonlinear forced displacement problem?

Question asked by Troy Hanson on Apr 18, 2012

I have an interesting problem that I'm unsure how to setup.  I created the attached simplified example for reference/talking points.


I need to understand how the order of assembly affects the final curvature of a beam.  Referencing simplified example 1, if the outside tie rods are tightened first, then the inside tie rod, I would expect one solution.  If the inside tie rod is tightened first, then the outside rods, I would expect slightly different final beam deformation.  If not, I would like the solution to show me it is independent of assembly sequence.  Again, this is a simplified example and assumes the "down-riggers" have significant stiffness in the x direction compared to the beam's stiffness in the y-direction.  Ultimately I would like to use my simulation to determine assembly sequence(s), as well as change component stiffnesses to generate the desired beam curvature.


My problem is setting up Loads and BC's.  I initially thought I could force displace the ends of the tie rods to the down riggers, however where those two components actually end up in the x-direction is dependent on each of their (and their adjacent component's) stiffnesses.  Once coupled, their subsystem becomes much stiffer, so the same issue occurs when "hooking up" the inside tie rod at the next time step.   The gaps I'm dealing with are significant (large displacements) and as such the beam curvature is significant as well in addition to the time dependency.


Any thoughts or insight on how you would set this problem up?

Thanks in advance,