Fishing rod mechanics and curvature calculations

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Discussion Overview

The discussion revolves around the mechanics of bending a stainless steel beam with varying thickness to create a specific cam profile, similar to that of a fishing rod. Participants explore methods for calculating the required rate of change in thickness to achieve desired bending characteristics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant describes the need to create a cam profile by bending a stainless steel beam with a non-uniform thickness, specifying different cross-sectional dimensions at each end.
  • Another participant suggests using Finite Element Analysis (FEA) to derive the variation of cross-section from the deformed geometry, noting that this approach is somewhat unconventional.
  • A participant mentions that the deflection of a beam can be described by a 4th order ordinary differential equation and proposes that assuming a displacement function could lead to a formula for the moment of inertia.
  • There is a suggestion that using software for numerical analysis might be a simpler approach, implying a trial-and-error method could yield results without extensive mathematical derivation.

Areas of Agreement / Disagreement

Participants express differing opinions on the best approach to solving the problem, with some advocating for mathematical derivation and others favoring numerical methods. No consensus is reached on a single method or solution.

Contextual Notes

The discussion does not clarify the assumptions underlying the proposed methods, nor does it resolve the complexities involved in the mathematical modeling of beam deflection.

cardboard
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i am trying to make a piece of stainless steel of varying thickness bend in such a way that it creates a cam profile in much the same way a fishing rod works.

for example if the thick end has a 5mm by 10mm cross section and the thin end is 1mm by 10mm crosssection and the change in thickness is uniform down the length then a certain profile will be induced when the beam is bent if the thick end is fixed.

if the transition from 5mm to 1 mm is not uniform i.e. the first 100mm of the beam is 5mm and the last 100mm is 1mm then a different profile would be induced when bent about the thick end.

i need a method of calculating what rate of change in thickness i need to give a certain profile?

can anyone help?

thanks
 
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Finite Element Analysis!

Hmm deriving the variation of cross section from the deformed geometry is sort of reverse of what the usual trend is. But it can surely be done with a sound understanding of the subject.
 
are you asking for more detail or saying you don't have the knowledge in this area?!
 
From what I understand, the deflection in a beam is a 4th order ordinary differential equation. I would assume that if you assume a function for the displacement, then you can integrate (or maybe derivate) to obtain a function for the moment of inertia.
 
cardboard said:
are you asking for more detail or saying you don't have the knowledge in this area?!

I am telling you the easiest way out. Just crunch in numbers in a software & wollaa.(hit & trial method)

From what I understand, the deflection in a beam is a 4th order ordinary differential equation. I would assume that if you assume a function for the displacement, then you can integrate (or maybe derivate) to obtain a function for the moment of inertia.
Exactly. I just thought that would be a bit too much maths.

there you go...
http://www.efunda.com/formulae/solid_mechanics/beams/theory.cfm
 

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