Shear Stress of a particular length rod

[pukey123]

Just a quick question:

Wikipedia tells me that due the shearing stress, the yeild strength of Stainless Steel is 520Mpa

But how can i find out the Yeild strength of a 100mm long rod with diameter 10mm.

Is the info for wikipedia based on a 1mx1mx1m cube? or some sort of SI unit.

Cheers

 

[mgb_phys]

The stress doesn't depend on the length of the rod - it only depend son the cross section area.
Mpa is mega pascal - is a unit of pressure, 1 pa is one Newton/m^2
So 1Mpa is around 100,000 Kg/m^2, or 145psi

 

[pukey123]

i see, but the what cross section area are the stresses relating to? and does it also depend on the shape?

If i see the value of 520MPA in a book for s steel, how can i use that to aplly it to a rod with a given diameter?

 

[Andy Resnick]

Calculating the deformation of a rod requires three things- the applied stress, the mechanical properties of the rod, and the geometry of the rod. All you have right now is (I'm guessing) the Young's modulus for a particular type of stainless steel and the geometry of the rod.

Try surfing through these, see if it helps:

http://www.clag.org.uk/beam-menu.html
http://www.mhhe.com/engcs/engmech/beerjohnston/mom/lectureppt.mhtml
http://www.grantadesign.com/resources/shapes/solutions/elastic.htm

Note- thin beams have a simple approximate solution. Yours, with an aspect ratio of 10, may or may not be amenable to that approximation.