STUDY ON FRICTION PARAMETERS MEASUREMENT OF MOVEABLE CONTROL SURFACES

Analytical and numerical methods are adopted to study the effects of the Coulomb friction on structural dynamic response. Based on the characteristic that the Coulomb friction in time domain can be transformed into a square wave function using Fourier expansion, the series response of a single degree of freedom system under harmonic excitation can be obtained. The result implies that the Coulomb friction will cause odd frequency multiplication components in the frequency response, except the fundamental frequency component. When the excited frequency is 60.5% of natural frequency, the amplitude ratios of odd frequency multiplication components to the fundamental frequency one are linearly proportional to their corresponding frictional forces. Numerical simulations show that the characteristic mentioned above can be extended to a moveable control surface model with two degrees of freedom. As a result, the Coulomb friction parameters can be measured through vibration experiment, which is verified by laboratory measurements.