The von Mises yield criterion is
\begin{equation} \label{b1}
    f = (3J_2)^{1/2}-\sigma_y = 0
\end{equation}
Assume that the stress states above are calculated with a linear elastic
analysis. Which of the stress states A to D above will give a plastic
deformation? The effective stress $\sigma_{eff}$ is defined by:
\begin{equation} \label{b1}
  \sigma_{eff} = (\frac{3}{2}S_{ij}S_{ij})^{1/2}
\end{equation}
The material yields at $\sigma_{eff} = 2000$ MPa.