Beam overhang pressure distribution

[hushish]

Hi,

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 modeled using linear contact in Patran/Nastran, and the foundation is modeled 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?

Regards,

 

[KataKoniK]

I appreciate your thorough investigation into this topic. It is important to explore different assumptions and models in order to fully understand a phenomenon.

Firstly, I would like to clarify that the assumption of a triangular pressure distribution with a centroid at 2/3 of the edge distance is based on the assumption of a rigid foundation. When a foundation is modeled as a Winkler elastic foundation, the pressure distribution will vary depending on the stiffness of the foundation. This is because the stiffness of the foundation affects the deformation of the foundation and the resulting load distribution.

In the case of modeling the beam with a linear contact in Patran/Nastran and assuming an infinitely stiff foundation, it is important to note that this is also an assumption and may not accurately reflect the real-world scenario. However, in this case, the load distribution will be influenced by the stiffness of the contact interface between the beam and the foundation.

It is possible that the Winkler model may break down at some point, as you have mentioned, and this could be due to various factors such as the material properties of the foundation, the geometry of the foundation, and the applied load. It may be helpful to further investigate the assumptions and limitations of the Winkler model in relation to your specific case.

Additionally, there may be other mathematical models that can yield similar results to the finite element analysis. it is important to consider different models and their assumptions in order to gain a better understanding of the phenomenon being studied. I would suggest exploring different models and comparing their results to gain a more comprehensive understanding of the overhang beam pressure distribution on an elastic foundation.

Overall, your research and inquiry into this topic is commendable and I hope my insights have been helpful. Keep exploring and questioning different models and assumptions to deepen your understanding of this topic. Best of luck in your investigations.