# Young's modulus times second moment of area

1. Mar 16, 2009

### Pietair

Good day,

Im am wondering what you get when you determine the following of a bar during a bending experiment:

(E x I) / y

E = the Young's Modulus [kgf/mm^2]
I = Second moment of area [mm^4]
y = half of the bar height [mm]

Is there a name for this term? And what does this term represent?

2. Mar 16, 2009

### Mapes

The reciprocal of this term is the magnitude of the normal strain at the surface per unit bending moment (because $|\sigma_{\rm{max}}|=My/EI$). EI alone is called the flexural rigidity.

3. Mar 17, 2009

### Pietair

Allright, thanks a lot.

Then I have got one question left:

In the formula:
(M/I) = (E/R)

What does "R" represent?

4. Mar 17, 2009

### Mapes

The radius of curvature of the bending beam.