Reply To: Connection Stiffness Ansys AQWA

[Shuangxing Du]

Critical damping is calculated by C/[2*sqrt(MK)]=C/[2K/omega_r]=C*omega_r/(2K). For roll motion, K is the hydrostatic stiffness of roll-roll, omega_r is the natural frequency of roll motion.

From this equation, the equivilant frequency-independent roll damping for each structure section could be 5%*(2K)/omega_r, where K is the hydrostatic stiffness of roll-roll of each structure section.

It is harder to find out the equivalent dampings of each structure sections for pitch motion, as the the viscous damping for pitch is for the whole structure.