Viscous damping estimation of structures using extreme frequency bandwidth method

The classical half-power bandwidth (HPB) method is known as a simple and widely used method to identify damping in experimental research on structural vibrations. However, this method is only effective in systems with small damping and separate natural frequencies. This paper presents the extreme frequency bandwidth (EFB) method and proposes a formula to estimate the viscous damping ratio from the extreme points of the real part of the frequency response function (FRF) in the displacement spectrum analysis of structures. The displacement FRF is obtained by Fourier transform of the simulated load and response signals of the system. The results show that the EFB method can identify the viscous damping in structures that have one or more degrees of freedom with different damping levels.