Oct24-12, 01:36 AM
Please do not shout at me if you find this query posted on another thread; I am spreading my net wide.
I am investigating the overhang beam pressure distribution when part of the beam is resting on an elastic foundation. We are all aware of the assumption that when a moment is reacted at the foundation, the reacting end beds-into the foundation and creates a triangular pressure distribution; the centroid of which is at 2/3 of the edge distance L.
If I model this beam, assuming the foundation to be a Winkler elastic foundation, as the elastic foundation constant increases, the centroid of the distributed load approaches the simple support. Essentially, the stiffer the foundation, the closer it approaches to a second simple support very close to the simple support reacting the tension load. However, if this beam is modelled using linear contact in Patran/Nastran, and the foundation is modelled as infinitely stiff, the centroid does not decrease to less than 27% of L, the edge distance of the beam on the foundation. I have even considered lift-off of the beam in the Winkler model.
Is there an explanation for this? Obviosuly, the Winkler foundation model breaks down at some point, but what other mathematical model would yield the FE result?
1. The problem statement, all variables and given/known data
2. Relevant equations
3. The attempt at a solution
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