Hertzian contact stress

How's about what Wikipedia has to say about Hertzian Contact Stress?

Hertzian stress criteria was developed for two spherical surfaces of different radii bearing against each other.

In the case illustrated, there are two cylindrical surfaces bearing together. If they are accurately machined to fit, the bearing stress should be Fx/td where t is the plate thickness and d is the diameter of pin.

From my recollection, hertzian stress is a result of both normal and shear stress in curved surfaces. Your link example illustrates normal stress only. If you were to apply an axial force on a pin while the link was loaded, you would generate shear stress at the pin/link interface. In the Hertzian regime, the maximum shear stress would occur as two parallel lines along the axis of the pin. Hertzian stress is most often computed for the stress between two spherical surfaces of different radii under combined normal and shear stress. In that case, the maximum hertzian stress ocurrs along a circular path.

Hertzian stresses apply to static one directional loads as well. They are used to determine i.e. the stress concentration in the corner of a groove in an axially loaded shaft or point loads. There are look-up tables for all sorts of situations, I can remember seeing the tables in my Newnes Engineers Handbook which, unfortunately, I don't have with me but I guess the tables would be available elsewhere.

This thread discusses hertzian stresses of a cylinder in a hole & may help.

'Hertzian stress' is often used in lieu of 'contact stress', regardless of Hertz's original solution for sphere contact. In this sense, you are corrent on point 1. But your point 2 amounts to a few weeks' university lecture time. Too much info to share over the internet.

Consider buying a handbook on mechanics (many good ones to choose from). Make the investment and save yourself the time. You likely won't find the comprehensive calculations on-line, only sporadic info and puzzle pieces...

Hi!

If the problem is still to be solved, I have some comments.

The consideration for contact stress would depend on how loose is the fit between the pin and the link.

Do you have dimensions and loads?

regards

dc-link