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Principal Stresses

Entity names: P1, P2, P3, worstPS, worstPSx, worstPSy, worstPSz

The principal stresses $\sigma$ are named P1, P2, P3. From the three principal stresses $\sigma$ the absolute maximum value will be calculated and named worstPS. For example if a node has the three values 100, 0 and -110 MPa then -110 MPa would be shown. The three principal stresses $\sigma$ are given by the three roots of the equation:


\begin{displaymath}\sigma^3 - (\sigma_{xx}+\sigma_{yy}+\sigma_{zz})\sigma^2 + (\...
...{yy}\sigma_{zz}+\sigma_{zz}\sigma_{xx}-\tau_{xy}^2-\tau_{yz}^2-\end{displaymath}


\begin{displaymath}\tau_{zx}^2)\sigma - (\sigma_{xx}\sigma_{yy}\sigma_{zz}+2\tau...
...\tau_{yz}^2-\sigma_{yy}\tau_{zx}^2-\sigma_{zz}\tau_{xy}^2) = 0 \end{displaymath}

In addition the the three components of worstPS are stored as well. The entity-names are: worstPSx, worstPSy, worstPSz. They are derived from the following equation:


\begin{displaymath}
\left [
\begin{array}{ccc}
\sigma_{xx}-\lambda & \sigma_{xy}...
... ]
=
\left [
\begin{array}{c}
0\\
0\\
0
\end{array}\right ]
\end{displaymath}



root 2006-02-18