Q: cantilevered cylindrical shell

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    Cylindrical Shell
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Discussion Overview

The discussion centers around the static deformation of cantilevered cylindrical shells under transverse loads, particularly in the context of gravitational loading on horizontal cantilevered pipes. Participants explore the complexities involved in analyzing such structures, especially regarding wall thickness and modeling approaches.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning
  • Experimental/applied

Main Points Raised

  • One participant seeks references for analyzing the deformation of cantilevered cylindrical shells under transverse loads, noting a lack of resources that address this specific scenario.
  • Another participant suggests that the analysis depends on the wall thickness of the tube, indicating that thick-walled tubes can be treated as simple beams, while thin-walled tubes require detailed shell structure analysis.
  • A later reply mentions the need for numerical methods or finite element analysis (FEA) for most real-world problems, implying that analytical solutions may be limited.
  • One participant expresses interest in modeling a primary cilium and discusses the appropriateness of modeling microtubules as either orthotropic beams or isotropic shells, highlighting uncertainty in the best approach.
  • Another participant shares an example of a simple FEA of a thin-walled tubular cantilever beam with a tip load, suggesting practical application of the discussed concepts.
  • There is a question raised about the existence of an analytic solution for small (linear) strains in the context of the shared FEA simulation.

Areas of Agreement / Disagreement

Participants express differing views on the modeling approaches for cantilevered cylindrical shells, particularly regarding wall thickness and the applicability of analytical versus numerical methods. The discussion remains unresolved regarding the best modeling strategy for specific applications.

Contextual Notes

Limitations include the dependency on wall thickness and the complexity of real-world loading conditions, which may not be fully addressed by simple analytical models.

Andy Resnick
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I'm trying to find a decent reference that discusses the (static) deformation of a cantilevered cylindrical shell under a transverse load- for example, how a horizontal cantilevered pipe will deform due to gravitational loading. Everything I can find either discusses axial loading or considers non-cylindrical beams (I-beams, etc.).

Thanks in advance!
 
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Depends on the wall thickness of the tube .

Tubes with walls which are relatively thick compared to tube diameter can be treated as simple beams .

Tubes with walls that are relatively thin compared to tube diameter have to be treated as shell structures and analysed in detail . Some simple configurations of tube geometry and loads can be analysed mathematically but most real world problems require use of either direct numerical methods or FEA .

Can you tell me if you have a specific problem to deal with ?
 
Nidum said:
Depends on the wall thickness of the tube .

Tubes with walls which are relatively thick compared to tube diameter can be treated as simple beams .

Tubes with walls that are relatively thin compared to tube diameter have to be treated as shell structures and analysed in detail . Some simple configurations of tube geometry and loads can be analysed mathematically but most real world problems require use of either direct numerical methods or FEA .

Can you tell me if you have a specific problem to deal with ?

Thanks!

Specifically, we want to better model a primary cilium:
http://www.physiology.org/doi/abs/10.1152/ajprenal.00172.2017

We are 'inspired' by some work on modeling microtubules as either orthotropic beams or as isotropic shells (honestly, not sure which is more appropriate). At this point, I'm mostly just surprised that this 'simple' problem doesn't seem to be so simple...
 
tube as beam deflection v3.png

Just for interest this is an example of a very simple FEA of a thin wall tubular cantilever beam with tip load .

(From one of my past engineering projects) .
 

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Nidum said:
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Just for interest this is an example of a very simple FEA of a thin wall tubular cantilever beam with tip load .

(From one of my past engineering projects) .

Thanks! Sorry for the late reply... had to deal with a bit of nasty business. That simulation is *exactly* the phenomenon we are interested in; is there no analytic solution, even for a small (linear) strain?
 

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