# Mohrs Circle, Von Mises and Minimum Yield Strength Help!

 P: 5,462 Mohrs Circle, Von Mises and Minimum Yield Strength Help! Well I agree with your figures for both the Mohr circle and by direct calculation. Incidentally you do not need a Mohr circle for the stress state indicated. If σy = 0 then Von Mises can be written $$Y = \sqrt {\sigma _x^2 + 3\tau _{xy}^2}$$ as an alternative to the formula using σ1 and σ2 So I would be interested if you have a reference or could post more of this book.
 P: 5,462 Are you sure you haven;t got the Tresca and Von Mises ctiteria mixed up? The formula for the Tresca max stress is $$Y = \sqrt {\sigma _x^2 + 4\tau _{xy}^2}$$ or the max difference of principel stresses. Either way that works out to the 660.4 MPa in your book.