Hertzian Contact Stresses - Please Help!!

[roberto000000]

I'm trying to show my working for maximum shear stress for a sphere on a flat plate. The answer is 202.9 MPa.

Please can somebody show me the working out, I'm stuck at calculating the principal stresses and I cannot understand the z value, which is apparently 0.225mm.

When I input the values below into the equation for principal stress, I get 2.57x1010Pa, which gives me the wrong value when inputted into the shear stress eq.

I'm losing my mind over this!

Radius of sphere = 50mm, E = 200GPa, Poisson's Ratio = 0.3, Force = 300N, Pmax = 654.5MPa, z=0.225mm

 

[prex]

Please clarify, it is unclear what exactly you are after. And what's z ?

prex
[URL unfurl="true"]http://www.xcalcs.com[/url] : Online engineering calculations
[URL unfurl="true"]https://www.megamag.it[/url] : Magnetic brakes and launchers for fun rides
[URL unfurl="true"]https://www.levitans.com[/url] : Air bearing pads

 

[jari001]

A diagram of the scenario you're trying to analyze will help tremendously.

 

[dvd]

I have had good understanding on contact stresses from "Formulas for Stress, Strain, and Structural Matrices" by Walter D. Pilkey, John Wiley & Sons, chapter 9.

The Z parameter is distance from contact area to location of maximum shear stress.

The problem is thus

Go to the library or bookstore or internet ...