Learning Forum

[Hussam Khresat]

Hi all 

I have a cantilever beam length=48 in and square cross section 1x1 in. A vertically upwards force is applied at the free end = 50 lbs. The beam is massless.

I am trying to calculate shear stress XY at 20 in from the fixed support at the top of the CS in a static structural analysis. 

I am getting a non zero shear force which I think is wrong because Tau=VQ/Ib right?

Attached is a picture of my model. 

 

[Onkar Patil]

 

Hi Hussam, 
I tried to replicate the same on my end but I am getting the correct results (Very close to 0 value of shear stress). 
Can I ask how and to what you scope the result? 

Thanks!

 

[wrbulat]

It may be instructive to look at the calculated nonuniform distribution of the xy shear stress over the cross section of the beam by mapping it onto a construction surface.

We know that it sure as heck should not be constant:

Shear Stress Distribution in Beams (profkodali.blogspot.com)

 

You can create a surface as follows:

Create a coordinate system at the "cut" location with its z axis aligned with the global x axis, then, in the tree:

RMB on Model

 Insert > Construction Geometry > Surface

Choose the coodinate system mentioned above in Details.

Then scope xy shear onto the surface under the Solution branch of the tree.

 

You may need to refined the mesh over the beam cross section to spatially resolve the distribution of shear. 

Here's an image from a quick hack I just created that might help you further (sorry, we're not allowed to attach models to Forum posts):

Happy New Year,

Bill