Maximum Deflection in Columns: Fixed & Free End

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Discussion Overview

The discussion revolves around determining the maximum deflection in a vertical column with one end fixed and the other free, particularly under axial loading conditions. Participants explore various resources and theories related to column deflection, stability, and buckling behavior.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants inquire about the method to find maximum deflection in a column with one end fixed and the other free, specifically under axial load.
  • Links to external resources on cantilever beams and Euler's column formula are shared, indicating a search for relevant mathematical frameworks.
  • There is a discussion about whether a vertical column under axial load is analogous to a cantilever beam rotated 90 degrees, with requests for diagrams to clarify this point.
  • One participant suggests that the deflection may not be specific, as the column could either be stable and return to center or unstable and fail catastrophically.
  • Another participant counters that a column can buckle while remaining elastic, referencing the "theory of the elastica," and notes that it can exhibit stable bending behavior.
  • References to classical literature and personal experiences with post-buckled columns are provided to support the argument about stability in bending.

Areas of Agreement / Disagreement

Participants express differing views on the nature of deflection in columns under axial load, with some asserting that specific deflection is not applicable while others argue for the possibility of stable bending behavior. The discussion remains unresolved regarding the exact conditions and outcomes related to maximum deflection.

Contextual Notes

Participants note that boundary conditions significantly affect the load-bearing capacity of columns, and the discussion touches on the complexities of applying bending equations to different loading scenarios. There is an acknowledgment of the need for clarity on definitions and assumptions related to stability and deflection.

Gurasees
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How can I find maximum deflection in a column with one end fixed and other free?
 
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Gurasees said:
But the column is vertical and it has axial load on it.
Isn't that the same thing, just rotated 90 degrees? Can you post a diagram?
 
Gurasees said:
How can I find maximum deflection in a column with one end fixed and other free?

Keywords:
deflection,
column,
axial,
loaded

so I looked up "deflection axial loaded column"
and received a bunch of hits to look through.
Perhaps one discussion can be found that is acceptable, as the mathematics is most likely something you are not yet acquainted with. ( Maybe you are. )

Such as,
http://ocw.nthu.edu.tw/ocw/upload/8/258/Chapter_9-98.pdf --> for a cantilever beam
https://ocw.mit.edu/courses/aeronau...ng-2006/materials-structures/gm12_13notes.pdf
http://www.engr.mun.ca/~katna/5931/Buckling2.pdf --> discusses pin-support
( But also a discussion on EXTENSION OF EULER'S FORMULA TO COLUMNS WITH OTHER END CONDITIONS )

You will notice that the equation for bending

d2w/dx2 = M / EI

applies to either transverse or axial loading. ( As far as I remember from beam loading )

Boundary conditions are what makes the difference.
the support and loading points can be either fixed or pinned or free, and that makes a difference on how much load the column can support safely.
 
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russ_watters said:
Oh, right - axial. I don't think there is a specific deflection, since the column is either stable - and returns to center - or unstable - and catastrophically fails

Often this is correct, but not in all cases. With the necessary material properties, a column can buckle but remain elastic. This has been studied extensively in the classical literature under the title "theory of the elastica." In such cases, the mode of deformation shifts from axial compression to bending. It can remain stable in bending just as well.. Long ago, I built a spring using columns in the post-buckled state and it worked beautifully.
 
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