I have to do a durability approval of feather key (shaft-hub connection) and the formulas are dependent if the shaft respectively the hub is ductile or brittle.
But what is the decision about to say it is ductile or brittle.
- My norm for feather key isn’t saying anything how to distinguish if the metal is ductile or brittle.
- The norm for pressfits uses the parameter fracture elongation and reduction of area.
- And the literature is talking about brittle metal when the Maximum Stress Theory is valid $(\sigma_{limit}/\tau_{limit}=1)$ and ductile metal when the Shear Stress Hypothesis is valid $(\sigma_{limit}/ \tau_{limit}=2)$.
- $\sigma_{limit}$ is tensile strength
- $\tau_{limit}$ is the strength when plasticity begins
Okay, there are many possibilities… But which one is the right possibility? Or is there a connection between my findings that I’m not aware of?
Thanks in advance for your help.