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

In summary, the conversation is discussing a beam bending problem and the formula for calculating deflections at the load for a straight beam. The poster also suggests using Castigliano's Method for solving the problem.
  • #1
tlangdon12
1
0
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
    2.9 KB · Views: 2,007
  • Std Beam w overhanging point loads.GIF
    Std Beam w overhanging point loads.GIF
    730 bytes · Views: 969
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  • #2
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
 
  • #3
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.
 
Last edited:

1. What is beam bending?

Beam bending is a phenomenon that occurs when an external load is applied to a beam, causing it to deform or bend. This can result in stress and strain within the beam, which can affect its structural integrity.

2. What is a cranked beam?

A cranked beam is a type of beam that has one or more bends or kinks in its shape. These bends are typically used to distribute the load more evenly along the length of the beam, making it stronger and more resistant to bending.

3. How does the cranked shape affect the beam's strength?

The cranked shape of a beam can significantly increase its strength and load-bearing capacity. This is because the bends or kinks help to distribute the load more evenly, reducing stress concentrations and preventing the beam from bending or breaking under heavy loads.

4. What factors influence the amount of beam bending in a cranked beam?

The amount of beam bending in a cranked beam can be influenced by several factors, including the material properties of the beam, the magnitude and location of the external load, and the geometry of the beam (such as the length and angle of the bends).

5. How is beam bending in a cranked beam calculated?

Beam bending in a cranked beam can be calculated using various mathematical equations and principles, such as the Euler-Bernoulli beam theory or the method of sections. These calculations take into account factors such as the beam's cross-sectional properties, the applied load, and the beam's support conditions.

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