Modal Damping
Modal damping is defined as a ratio of the critical damping Ccr for each mode. Critical damping Ccr is the least amount of damping that causes a system to return to its equilibrium position without oscillating.
The modal damping ratio can be determined accurately with proper field tests. The ratio varies from 0.01 for lightly damped systems to 0.15 or more for highly damped systems.
When experimental data is not available, use data from a similar class of systems to determine the damping properties. Smaller ratios are more conservative since higher ratios reduce vibration amplitudes. In general, neglecting damping leads to a conservative estimate of the system's response.
Click here for a list of damping ratios for different systems.
Related topics
Global Damping