Stresses in Beam

[MaryJ]

Could someone let me know if I am correct on these statement. My coworker asked me and am not 100% clear on the fact anymore.

1) Max Shear stress occurs at the centroid of a beam section

2) Max compressive stree occurs at the top of a beam

3) Bending stress is maximum at the outer edge of a beam and is zero at the neutral axis.

4) Horizontal Shear stress is zero at the outer edge of a beam.

 

[MA_PE]

Assuming your questions are for a homogeneous rectangular beam on simple supports with a vertical load on the top.

1) The maximum shear load will be at the support, the maximum shear stress is at the neutral axis, no necessarily the centroid.

2) The maximum compressive stress due to bending would occur on the opposite face from the tension side. For a vertically loaded beam, the maximum compressive stress would be at the top. If the beam were subject to pure compression at it ends with no bending, then the compressive stress would be uniform through out the crossection.

3) The maximum tension stressdue to bending would be at the outer edge on the tension face. Bending stress is zero at the neutral axis.

4) Yes, shear stress is zero at the outer edge of the beam.

 

[KevinNg]

Good job MA_PE.

I have no better answer than MA_PE and agreed with MA_PE.

 

[Ble_PE]

To go along with what MA said, here are some diagrams which you should be able to find in any mechanics of materials book:

 

[MaryJ]

Thanks to all for helping!

 

[kevo_55]

Fancy drawings Ble!

Now, what book did you get them from? :Chris:

 

[Ble_PE]

From the great book of google... h34r:

 

[kevo_55]

I like that answer!

 

[MA_PE]

rect beam? damn near killed it.

 

[Judowolf PE]

I know I'm a lowly EE, but I use a free/almost free software series for calculating stress/strain...mdsolids. Anyone else use this?

 

[Judowolf PE]

The drawings reminded me of it, I haven't used it in a while though!

 

[pbrme]

I know I'm a lowly EE, but I use a free/almost free software series for calculating stress/strain...mdsolids. Anyone else use this?

I used that in college. Helped for generating quick shear-moment diagrams. I've done enough of them now I just hand sketch.