Does This Flexural Stress Equation Apply to Different Beam Conditions?

In summary, the equation for calculating flexural stress of a beam with a rectangular cross section only applies to a solid horizontal rectangular beam of negligible weight and of length L and pin supported at each end, with a concentrated load P applied at its midpoint. The equation is My/I, where M is the bending moment, y is the distance from the neutral axis, and I is the Area Moment of Inertia. This equation does not apply to filled or hollow beams, or when the force is applied at different points on the beam.
  • #1
Aragorn49
11
0
From what I know the equation for calculating flexural stress of a beam with a rectangular cross section is:

3PL/2Bd2

I have two questions about the validity of this equation. I will post a pic I just made to show what I mean:

1st question, Does this equation work both for filled beams (A,) and dull beams (B,)?

2nd question, Does this equation work both for when the force is applied in the exact center of the beam (C,) and for when the force is applied to the edge of the middle area (D,)?

2m696jt.png
 
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  • #2
The equation you listed applies only to a solid horizontal rectangular beam of negligible weight and of length L and pin supported at each end, with a concentrated load P applied at its midpoint. You don't want to blindly apply equations. In general, the flexural stress in beam at a given point is My/I.
 
  • #3
Thank you for the help. But what does My/I mean? What quantities do the letters of that equation represent?
 
  • #4
I believe you posted on the wrong forum, since this does not appear to be a homework problem. M is the bending moment, y is the distance from the neutral axis, and I is the Area Moment of Inertia. For the beam in discussion, the max moment M occurs at mid point = PL/4, the moment of inertia I is bd^3/12, and the max stress at this section occurs at the outer fibers where y = d/2. Sound at all familiar?

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  • #5
I apologize if I posted on the wrong forum, I'm new here. It isn't exactly a homework problem, more like going a bit ahead of the stuff I learn right now. After I finished high school I had a few free years and now I want to get my physics knowledge back in shape cause I want to go studying structural engineering on a university. I forgot much of my high school knowledge so I'm pretty much relearning it right now, though sometimes I get the diesire to learn some more advanced stuff which really interests me.

Btw, where is the section where questions like these should be posted?

Thank you for your time
Aragorn49
 
  • #6
Oh no problem, I just didn't want to give you a precise answer without you showing your work if this was in fact a homework question.

In the future for questions along these lines, you can post under Engineering/General Engineering. Thanks.
 

FAQ: Does This Flexural Stress Equation Apply to Different Beam Conditions?

What is flexural stress calculation?

Flexural stress calculation is a scientific method used to determine the amount of stress or force applied to a material when it is bent or flexed. This calculation is important in engineering and material science to ensure the structural integrity and safety of various structures and materials.

How is flexural stress calculated?

Flexural stress is calculated by dividing the maximum moment (M) applied to a material by its moment of inertia (I). The equation for flexural stress is σ = M/I, where σ is the flexural stress, M is the maximum moment, and I is the moment of inertia.

What factors influence the flexural stress calculation?

The flexural stress calculation is influenced by several factors, including the type of material, its physical properties, the shape and size of the material, and the magnitude and direction of the force being applied. Other factors such as temperature and environmental conditions may also affect the calculation.

Why is flexural stress calculation important?

Flexural stress calculation is important because it helps engineers and scientists determine the maximum load a material can handle before it fails or breaks. This information is crucial in designing and constructing safe and durable structures and materials, such as bridges, buildings, and vehicles.

How is flexural stress used in real-life applications?

Flexural stress calculation is used in various real-life applications, such as designing and constructing buildings, bridges, and other structures. It is also used in the manufacturing of materials, such as concrete beams and steel bars, to ensure they can withstand the expected loads and forces they will encounter in their intended use.

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