Deflection of a Beam: Simple Solutions for Calculations

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    Beam Deflection
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Discussion Overview

The discussion revolves around the deflection of a two-dimensional curved and thin beam subjected to forces and a vertical load. Participants explore the implications of the beam's curvature and the mathematical approaches to calculate its deflection, focusing on the conditions under which certain theories apply.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant presents a problem involving a curved beam with specific forces and a vertical load, seeking a simple method for calculating deflection.
  • Another participant questions the validity of the beam's profile and requests more details about the loads applied.
  • Some participants suggest that the beam is pre-bent and propose subtracting the beam's profile from the elastic curve solution to the differential equation governing beam deflection.
  • There is a challenge regarding the appropriateness of using curved beam theory for a beam described as weakly curved, with some arguing that such theory is only applicable to significantly curved beams.

Areas of Agreement / Disagreement

Participants express differing views on the application of curved beam theory and the validity of the proposed methods for calculating deflection. No consensus is reached regarding the best approach or the assumptions about the beam's curvature.

Contextual Notes

Participants note the importance of boundary conditions for solving the differential equation, and there is an acknowledgment of the need for clarity on the beam's curvature and loading conditions. The discussion highlights the dependence on specific definitions and assumptions regarding beam theory.

rsq_a
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I have the following problem, which involves a two-dimensional curved and thin beam with profile given by y= f(x). You can assume that the beam is only weakly curved (and so slopes are all quite small).

attachment.php?attachmentid=32450&d=1298409610.png


The beam's free-ends are both subjected to a force F1 and F2 (which will be given) and is also subjected to a load, w(x), directed vertically upwards.

Is there a simple question which gives the deflection of the beam?
 

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Can't see why your profile takes on the blue curve as shown, with the loads shown, perhaps you can supply more details?

Is this coursework or what?
 
Studiot said:
Can't see why your profile takes on the blue curve as shown, with the loads shown, perhaps you can supply more details?

The loads are arbitrary (some arbitrary load, w(x) will be applied). The blue curve is some arbitrary curve which represents the unstressed beam.

Is this coursework or what?

No, it's not coursework.
 
So the beam is pre-bent?

I suppose you could subtract f(x) from the elastic curve which is a solution to the fourth order differential equation of the beam.
You will need enough known boundary conditions to find the constants of integration.
 
Studiot said:
So the beam is pre-bent?

I suppose you could subtract f(x) from the elastic curve which is a solution to the fourth order differential equation of the beam.
You will need enough known boundary conditions to find the constants of integration.

Can you explain why you think this would be valid? As I understand it, the derivation of the beam equations for a curved beam would have to differ from the derivation for a straight beam.
 
You can assume that the beam is only weakly curved (and so slopes are all quite small).

You have already specified that the beam is nearly straight.
You only use curved beam theory for seriously curved beams.
 

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