added viscous damping ratio的用法和样例：
- According to the characteristic of viscoelastic dampers,simplified formulae of equivalent viscous damping ratio for structures with viscoelastic dampers are presented.
- The study indicates that the disorder of dry friction can significantly increase the resonant response of bladed disks, especially in the system with weaker coupling and larger viscous damping ratio.
- equivalent viscous damping ratio
- Cyclic test of laminated rubber damping bearing at low temperature and calculation of equivalent viscous damping ratio