How Do You Calculate the Load on a Prop Between Two Cantilever Beams?

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Discussion Overview

The discussion revolves around calculating the load on a prop situated between the free ends of two cantilever beams. Participants explore the relationship between beam deflections and the resulting load on the prop, considering various approaches and assumptions related to material properties and geometry.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant presents the deflections of the beams as equations, indicating a need to calculate the load on the prop based on these deflections.
  • Another participant expresses frustration regarding the original poster's engagement in the discussion, suggesting a need for courtesy in communication.
  • A later reply offers a method to find the load by subtracting the deflections of the beams to determine the elongation of the prop, followed by calculating strain, stress, and ultimately the force on the prop.
  • The same participant questions the definition of variable P and emphasizes the importance of the correct signs on the deflections to avoid cancellation in calculations.
  • The original poster acknowledges the proposed method as plausible and expresses intent to try it out.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the method for calculating the load on the prop, with multiple approaches suggested and some uncertainty expressed regarding the signs of the deflections.

Contextual Notes

The discussion includes assumptions about the material properties and geometry of the prop and beams, as well as the need for clarity on the definitions of variables used in the calculations.

phiska
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If i have two cantilever beams with a vertical prop between the free ends as shown in diagram, how do i find the load on the prop?

I have the deflections of the beams to be:

v (top beam)= (PL^3)/(3EI)
v(bottom beam)=(5WL^3)/(48EI)-(PL^3)/(3EI)

the prop is of diameter d, and length a, with youngs modulus E.

Any hints/help appreciated!
 

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I have been seeing you over here doing such questions. When we try to answer you, suddenly you disappear and never return to the thread for replying something.

Be a bit more polite and take into consideration the people who helps you.
 
I'm sorry, do not intend to appear rude.

I am very grateful to everyone who takes the time to help me.
 
This is totally just a guess...but...

Subtract your two deflections at the end of the cantilever to find out the elongation of the "prop." Given the initial length and the stretch, you can easily find the strain on the prop. Given strain and Modulus of Elasticity, you can now find stress. Given stress, and cross sectional area, you can solve σ=F/A for F, force.

This is just what I would try, and it is not guarenteed to work...seems like it would though.

edit: What is P by the way? Also, make sure the signs on your deflections are correct. If one of the PL.. terms was opposite, then when you subtracted the deflections, they would cancel each other out, making the problem significantly easier. That is, unless You need to add the deflections for some reason (maybe your deflections are poining in different directions).
 
Last edited:
That definitely sounds like a plausible solution.

I will have a go and see if it works out, and will let you know.

Thanks a lot
 

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