# 3.9.8: Principal States Transformation 🔷

With the **“Principal States Transformation”**-component one can define a tensor via first and second principal vectors **“Vec1”** and **“Vec2”** and get the components for a given direction **“DirX”**. This allows to e.g. calculate the bending moments or in-plane forces of a shell for a section perpendicular to **“DirX”**. **“N”** specifies the direction normal of a plane onto which **“Vec1”** and **“Vec2”** get projected before performing the transformation.

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