# G.17.3.3.1 Composite Damping

Composite modal damping is based on a weighted average of strain energies in each material, (or element), for each mode (eigenvector).

The critical composite damping term D_{J} for mode J is computed by:

${D}_{i}=\frac{\stackrel{n}{\underset{i=1}{\Sigma}}{\left\{{\varphi}_{i}\right\}}^{T}{b}_{i}\cdot \left[k\right]\cdot \left\{{\varphi}_{i}\right\}}{{\left\{{\varphi}_{j}\right\}}^{T}\cdot \left[K\right]\cdot \left\{{\varphi}_{j}\right\}}$

where= | ||

_{i}
| = | |

_{J}}
| = | |

_{i}
| = | |

= |