Suppose that, in the Taylor and Quinney tension-torsion tests, one has o = Y/2 and 1 = 3Y /4. Plot this stress state in the 2D principal stress state, Fig. 8.3.4. (Use Eqn. 8.3.15 to evaluate the principal stresses.) Keeping now the normal stress at o = Y/2, what value can the shear stress be increased to before the material yields, according to the von Mises criterion? B, Figure 8.3.4: yield loci in 2D principal stress space 6/-