Exact evaluation of natural frequency and damping ratio from a frequency response curve

Several experimental modal analysis techniques fit resonance peaks to the r esponse curves of a single degree of freedom system in order to identify th e natural frequencies and modal damping ratios. The present study identifie s a fundamental property of frequency response curves that allows the natur al frequency to be identified from a simple characteristic of the curve, in dependently of the damping ratio. After the natural frequency has been dete rmined, the damping ratio can be computed directly. The fundamental propert y holds for all values of damping, which eliminates the need to approximate either the natural frequency or damping ratio.