Cantilevered Beam Stress Calculation

If the beam is symmetrical, z is the distance from the center of the beam to either the top or bottom.

You sir have just made my day.

Thank you kindly :)

Are you certain that user is male?

Have you ever heard of a woman named Eugene before?

At least he is not named: NewGene Ledbetter from Mississippi.

Those folks can git'-R-dun'! But there are often hours of stories related to the fall-out of the task, and who needed relief from whatever poor critter was caught treed with one of them (John) that always insisted on giving the poor animal a "fightin'" chance!

Uh-oh; I been busted. Next up, they'll call me beerbelly or potbelly or worse.

The definitions are given in the table in your link, so not clear what your problem is. For standard beams section modulus Z is tabulated, so you don't need to calculate it from I and z. z isn't usually given, but for a symmetrical beam it's 1/2 the beam depth.

I did see the definitions, as I said what the definition of z was in my original post. My problem was that I just did not understand what it meant, I've never used that formula before and am not a mechanical engineer. You've given me the answer though at the end which is great so thank you.

There seems to be a whole lot of pointless comments here lads so let's leave it at that, the first reply to my post answered my question so it's all good.

Thanks!

A decent Statics, and/or Strength-of-Materials, and/or structural-analysis textbook should have a adequate explanatory diagram that shows how the key to the concept is that (little z) is the (usually vertical) lateral distance from the neutral axis of the beam, in the plane of bending, perpendicularly out to the extreme edge of the beam, all relative to the same point along the longitudinal axis of the beam...

Alternatively, go to:

https://www.engineeringtoolbox.com/section-modulus-conversion-d_1332.html

and see that, for your cantilever beam, ''little z'', in your website, is the distance from the origin (i.e.: the intersection of the x- and y-axis), and is, in this included website, upwards to the beam's top edge for tensile stress above the x-axis (i.e.: plus a/2), and downwards to the bottom edge for compressive stress below the x-axis (i.e.: minus a/2).