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I've come across a 4x4 stiffness matrix for a radial bearing with rotational stiffness. The stiffness matrix would look like

Kxx Kxy Kxϴ KxΨ
Kyx Kyy Kyϴ KyΨ
Kϴx Kϴy Kϴϴ KϴΨ
KΨx KΨy KΨϴ KΨΨ

I'm sure that unit of the terms Kxx Kxy Kyx Kyy are N/m and Units of Kϴϴ KΨΨ is N-m/rad.

My question is what are the units of the other rotational stiffness terms

Kϴx Kϴy KϴΨ KΨx KΨy KΨϴ  Kxϴ KxΨ Kyϴ KyΨ

Is it N-m/rad or something else?

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The stiffness matrix can be multiplied by an displacement vector $\begin{pmatrix}\Delta x\\ \Delta y\\ \Delta \theta\\ \Delta \psi\end{pmatrix}$ and then should give a vector containing forces and torques: $\begin{pmatrix}F_x\\ F_y\\ \tau_\theta\\ \tau_\psi\end{pmatrix}$.

Knowing the units of the vector components, you should be able to derive the units of the matrix components. Note that not all the components you ask for have the same units.

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