How can Castigliano's Method be used to solve for deflections in a cranked beam?

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SUMMARY

Castigliano's Method is an effective approach for calculating deflections in cranked beams subjected to point loads. The formula for deflection in a straight beam, given by y = Fc2(2c + 3b) / 6 EI, can be adapted for cranked beams by applying differentiation with respect to the applied forces. Key theorems relevant to this method include Enrico Betti's theorem, Clapeyron's theorem, Vereschagin's rule, and Simpson's rule. Utilizing these principles allows for a systematic approach to solving complex beam deflection problems.

PREREQUISITES
  • Understanding of Castigliano's Method for beam deflection
  • Familiarity with the modulus of elasticity (E) and second moment of area (I)
  • Knowledge of beam theory and mechanics of materials
  • Basic calculus for differentiation of functions
NEXT STEPS
  • Study the application of Castigliano's Method in various beam configurations
  • Learn about Enrico Betti's theorem and its implications in structural analysis
  • Explore Clapeyron's theorem for analyzing internal forces in beams
  • Investigate Simpson's rule for numerical integration in beam deflection calculations
USEFUL FOR

Structural engineers, mechanical engineers, and students studying mechanics of materials will benefit from this discussion, particularly those focused on beam deflection analysis and structural integrity assessments.

tlangdon12
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Hello all

I have a beam bending problem I need some help on.

I need to calcuate the deflections at the load (and in the plane of the load) for a simply supported beam with equal point loads overhanging the supports. However my beam is cranked as shown in the attached diagram of the problem geometry.

I know that for a straight beam the formula for the deflection (y) at the loads is

y = Fc2(2c +3b) / 6 EI

where

F = the force applied at each overhang
c = the distance of the overhang
b = the distance between the support
E = the modulus of elasticity of the beam
I = the second area of moment of the beam

(A diagram of the straight beam case is also attached).

Can anyone help me get started on solving this problem?

Thanks

Tony
 

Attachments

  • Problem Geometry.GIF
    Problem Geometry.GIF
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  • Std Beam w overhanging point loads.GIF
    Std Beam w overhanging point loads.GIF
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I see there are many posts asking to calculate deflections. The problem is it is very hard to explain these calculation theories, algorithms and the calculations take a long time. I recommend to find some building mechanic book to learn or to try search names:
1) Enrico Betti theorem
2) Clapeyron theorem
3) Vereschagin's rule
4) Simpsons rule
 
Anytime i see something start to get complicated i just use Castiglianos's Method. http://www.roymech.co.uk/Useful_Tables/Beams/Beam_energy_methods.html
If you were using this method you would differentiate with respect to the force to get the displacement in that direction (say the y direction). For the x direction you just put a force in there so that you can differentiate w.r.t. that force and once you have the equation you set that imaginary force = 0.
 
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