How to calculate elastic modulus

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    Elastic Modulus
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To calculate the elastic modulus and select the lightest suitable beam section, the maximum bending stress is set at 120 MPa. The initial calculations for stress and strain were incorrect due to misunderstandings about the force and area involved. The correct approach involves determining the maximum bending moment and using the bending stress formula (σ = M*y/I) to ensure the stress does not exceed the allowable limit. The elastic section modulus must be calculated to find a beam that meets the strength requirements while minimizing weight. The discussion emphasizes the importance of understanding beam properties and calculations for effective design.
  • #51
John54321 said:
So N-m being the denominator makes it be multiplied to N-M^2 end up as the numerator.

Sorry I don't get this ? maybe I need to sit down with someone and get this covered as I am running out of time.

Thanks for your help and patience.

If you start with ##\frac{10^3 N⋅m}{10^6\frac{N}{m^2}}##, then you get ##\frac{10^3 N⋅m}{10^6}⋅\frac{m^2}{N}## . Can you carry it the rest of the way, now?
 
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  • #52
So what your saying is the units just change over ie n-m = m-n
 
  • #53
John54321 said:
So what your saying is the units just change over ie n-m = m-n
It's not clear what you mean here.

Newtons multiplied by meters (N-m) is the same as meters multiplied by Newtons (m-N). That's the same as saying a * b = b * a.

And it's also not the point of writing ##\frac{10^3 N⋅m}{10^6}⋅\frac{m^2}{N}##

If you simplify the indicated multiplication, you'll see that the Newtons cancel entirely.

John54321 said:
Sorry I don't get this ? maybe I need to sit down with someone and get this covered as I am running out of time.

Thanks for your help and patience.

This may be a better use of your time. You have much remedial work in basic arithmetic and algebra which you need to catch up on. I'm not sure that studying beam problems is going to provide this catch up work, and the work will only get harder.

We are constrained by the rules of PF as to how much help we can give posters, and PF is not an efficient way to teach someone the basics of what they need to know.
 
  • #54
Hi steamking

If it's against Pf forum rules you can email me its vinto2@aol.com thanks
 
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