Correlation Coefficient (CQC Rule, Simplified: D_i = D_j)

ε_{ij} = \frac{8 \cdot D^{2} \cdot (1 + r) \cdot r^{\frac{3}{2}}}{{(1 - r^{2})}^{2} + 4 \cdot D^{2} \cdot r \cdot {(1 + r)}^{2}}

D	Damping value
r	Quotient of the natural angular frequencies (ω_j/ ω_i)

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Correlation Coefficient (CQC Rule, Simplified: Di = Dj)