Correlation Coefficient (CQC Rule)

ε_{ij} = \frac{8 \cdot \sqrt{D_{i} \cdot D_{j}} \cdot (D_{i} + r \cdot D_{j}) \cdot r^{\frac{3}{2}}}{{(1 - r^{2})}^{2} + 4 \cdot D_{i} \cdot D_{j} \cdot r \cdot (1 + r^{2}) + 4 \cdot ({D_{i}}^{2} + {D_{j}}^{2}) \cdot r^{2}}

D_i, D_j	Damping values
r	Quotient of the natural angular frequencies (ω_j/ ω_i)

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