Equation 3 of the Forced Vib Eqn Solution gives the amplitude response of a system operating in forced mode as:
(1)
By measuring the amplitude of the tip displacement at different driving frequencies, you can experimentally determine the system's amplitude response curve.
Utilizing LSQVIB, the predicted amplitude response (Equation 1) can be made to fit the experimental curve by a least squares determination of 
and 
.
The forcing frequency 
that causes the peak amplitude response is known as the resonant frequency. The resonant frequency is given by:
(2)
The resonant frequency is slightly less than the natural frequency.
