Deflection of partially loaded cantilever beam with non-homogeneous EI

Click For Summary

Discussion Overview

The discussion centers on the deflection of a cantilever beam with a fixed end, subjected to a uniform load applied from a distance L from the fixed end to the free end. The beam has a known rectangular cross-section and a total length h, with varying values of the modulus of elasticity (E) and moment of inertia (I) in two segments of the beam. Participants are exploring the mathematical approach to determine the deflection at the free end, w(h).

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant outlines their approach to solving for the deflection w(h) of the beam, indicating the need to consider the different values of E and I in the two segments of the beam.
  • Another participant suggests a method for solving the differential equations governing the deflection in each segment, emphasizing the need to apply boundary conditions at the transition point.
  • A follow-up question is raised regarding the calculation of the internal moments M1 and M2 for the two segments of the beam.
  • Further clarification is sought on how to find the reactions at the fixed end, which are necessary for determining the internal moments.

Areas of Agreement / Disagreement

Participants are engaged in a technical discussion with no clear consensus yet on the best method for calculating the moments or the deflection. Multiple approaches are being considered, and questions remain about the specifics of the calculations.

Contextual Notes

Participants have not yet resolved the assumptions regarding the loading conditions and the specific methods for calculating the internal moments. The discussion also reflects a dependence on the definitions of the variables used in the equations.

elepolli
Messages
2
Reaction score
0
TL;DR Summary: I have a cantilever beam with fixed end, known rectangular cross section and total length h. A uniform load is applied on the beam from a distance L from the fixed end, to the free end. The E modulus and inertia I are known, and they are two different constant values for 0<x<L and L<x<0.
I want to know the deflection w(h) of the beam at the free end.

This is my approach, what do you think?
IMG20240205134911.jpg
IMG20240205134911.jpg17071360447057202525035132297061.jpg
sideways beam 01.png
17071360447057202525035132297061.jpg
 
Last edited by a moderator:
Physics news on Phys.org
Your image is loaded sideways.

For ## 0 < x_1 \leq L_1## you solve

$$ \frac{d^2y}{dx_1^2} = \frac{M_1(x_1)}{E_1I_1} $$

Then, for ## L_1 < x_2 \leq L_2## you can solve

$$ \frac{d^2y}{dx_2^2} = \frac{M_2(x_2)}{E_2I_2} $$

Where the constants of integration (slope, deflection) at ##x_2 = 0 ## come from the end condition of the first section.
 
erobz said:
Your image is loaded sideways.

For ## 0 < x_1 \leq L_1## you solve

$$ \frac{d^2y}{dx_1^2} = \frac{M_1(x_1)}{E_1I_1} $$

Then, for ## L_1 < x_2 \leq L_2## you can solve

$$ \frac{d^2y}{dx_2^2} = \frac{M_2(x_2)}{E_2I_2} $$

Where the constants of integration (slope, deflection) at ##x_2 = 0 ## come from the end condition of the first section.
How should I calculate $M_1$ and $M_2$?
 
elepolli said:
How should I calculate $M_1$ and $M_2$?
Find the reactions at point A( force and moment). Then you write the internal moment at the end of the section as function of x in the typical way(by inspection, or integrating the shear).
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
4K
Replies
3
Views
13K
  • · Replies 3 ·
Replies
3
Views
8K
Replies
3
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
3
Views
4K
  • · Replies 3 ·
Replies
3
Views
4K
Replies
1
Views
2K
  • · Replies 14 ·
Replies
14
Views
10K
  • · Replies 1 ·
Replies
1
Views
3K