Some terms in beam stress calculation

[ghensky]

1. For beam stress, are moment of inertia and bending moment, are they same thing?
2. Modulus of elasticity and section modulus, are they same thing?

 

[MotorCity]

1. No

2. No

 

[JStephen]

If anybody wonders, we mechanical engineers DO learn this stuff in college in Strength of Materials classes; it's also fairly essential for machine design and vibrations classes.

 

[rb1957]

I guess some of you didn't ...

another day in paradise, or is paradise one day closer ?

 

[jayrod12]

No rb.. it's that for some of them, strength of materials was a course they deleted from memory the second they walked out of the exam, like Calculus 3 and 4 for me.

 

[rb1957]

"learn and forget" = learning ?

no, for me learning > "learn and forget" ...

another day in paradise, or is paradise one day closer ?

 

[dhengr]

You don’t got to know nothing no more to call yourself an engineer. Anyone can call themself an engineer, the term has very little real meaning to the general public, its been thrown around so loosely. It’s all on the internet, you don’t gotts to learn nothin, just Google it. And, that’s how they get here. Then, when they signed in, they don’t bother to read that these forums are for engineers and other technical professionals. Those instructions obviously don’t apply to them.

 

[ghensky]

Thanks guys. Looking at the units of the moment of inertia (unit^4) and bending moment (lb-ft or N.m), I thought so. Same goes for Modulus of elasticity (no unit) and (unit^3). Just needed a validation to avoid going way back to refresh memory.

 

[canwesteng]

Modulus of elasticity is a unit of force/area.

 

[msquared48]

This is basic stuff... What is your background OP?

Mike McCann, PE, SE (WA)

 

[rb1957]

just because the units are the same, doesn't make them the same thing.

Modulus of elasticity has the same units as stress, but they are very different things.

despite what you might learn for this post, please go back to the books and refresh.

another day in paradise, or is paradise one day closer ?

 

[JeanLucPicard]

Isn't this common knowledge in engineering?

Live long and prosper!

 

[ghensky]

@msquared, fluid dynamics

 

[ghensky]

@jeanlucpicard, common in the undergrad course, but then become a function of how frequently you use them, right?

 

[ghensky]

@canwesteng, thanks. copied the strain instead of pressure.

 

[TehMightyEngineer]

http://en.wikipedia.org/wiki/Elastic_modulus

http://en.wikipedia.org/wiki/Moment_of_inertia

http://en.wikipedia.org/wiki/Section_modulus

http://en.wikipedia.org/wiki/Bending_moment

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)