Negative Ten Decibels Method for Damping Identification of Light Damping Structure

Half power method is commonly used in structural damping identification because of its simplicity in algorithm. But when the damping is very small, half power method will lead a big error. In order to get more accurate result of small damping structure, this paper suggests using negative ten decibels method (N-10dB) instead of half power method. N-10dB method takes 10-dB bandwidth into consideration, differs from 3-dB of half-power method. The theory of this method is given firstly and proves that it is very simple in algorithm. Subsequent simulation and experiment show that, compared with half power method, N-10dB method have stronger noise resistance, higer precision and is more stable in repeated measurements. Except that, the N-10dB method is also practical in engineering test.