Finding dimensions of a beam using shear, moment, and moment of Inertia

Click For Summary

Discussion Overview

The discussion revolves around determining the dimensions of a beam using shear, moment, and moment of inertia. Participants explore the application of these concepts in a homework context, focusing on the analysis of bending stress and moment diagrams.

Discussion Character

  • Homework-related
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant suggests starting by equating the bending stress to the allowable bending stress to find the dimensions.
  • Another participant asks for a loading diagram of the cantilever that would experience the most stress, indicating the importance of understanding bending moment definitions for constructing moment diagrams.
  • A different participant mentions using weight density to determine weight distribution and treating the beam as a simply supported beam, questioning the validity of this approach.
  • One participant challenges the assumption of a simply supported beam, pointing out the discrepancy with the original question that specifies a cantilever beam.

Areas of Agreement / Disagreement

Participants express differing views on the type of beam being analyzed (cantilever vs. simply supported) and the appropriate methods for determining dimensions, indicating that the discussion remains unresolved.

Contextual Notes

There are unresolved assumptions regarding the beam type and loading conditions, which may affect the analysis and calculations presented.

haleystew
Messages
3
Reaction score
0

Homework Statement



hwnotebook26.jpg


Homework Equations



Moment of Inertia equation: I=(1/12)bh^3
Stress and Strain equations: Sigma= -(M*c)/I Tao = (V*Q)/(I*t)

The Attempt at a Solution



I know I need to use shear and moment diagrams to find the max moment so I can use the Stress diagram to find the Moment of Inertia to find the dimensions of the cross section, but I can't figure out how to get started. Any help would be great. Thank you.
 
Physics news on Phys.org
Wouldn't you want to start by setting sigma in your equation equal to the given allowable bending stress? Give it a try.
 
Can you draw a loading diagram for the cantilever you think has the most stress? Do you know a definition of bending moment that will enable you to draw the bending moment diagram?
 
I am using the weight density to find the weight distribution over the entire area and then treating that as a simply supported beam. Will this work?
 
If it is a simply supported beam, rather than a cantilever (as it says in the question !) where are the two supports?
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 2 ·
Replies
2
Views
4K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
Replies
5
Views
4K