stress curve in the notch effect?

[aliex]

Hello,
i was trying to understand this stress curve in the notch effect. σy I can understand but σx and σt not. Could you please explain?

Thank you

 

[Sparweb]

Poisson's ratio.
It exists in all stressed materials, not just at notches.

STF

 

[metengr]

This is an application where you have a tri-axial state of stress in material at a notch. You can search for this information and compare with uni-axial and bi-axial states of stress.