全动操纵面系统中摩擦参数测量方法研究

STUDY ON FRICTION PARAMETERS MEASUREMENT OF MOVEABLE CONTROL SURFACES

通过解析方法和数值方法研究了库仑摩擦对结构动响应的影响规律。利用库仑摩擦在时域上能够傅里叶展开为方波函数的特点,得到含库仑摩擦的单自由度系统在简谐激励下的级数响应,结果表明,库仑摩擦的引入导致结构的频域响应中,除了激振频率成分外,还会有奇数倍频的成分,在激振频率为0.605倍固有频率时,奇数倍频成分与激振频率成分的幅值比例是摩擦力的线性函数。通过数值方法证明,上述规律能够推广到二自由度的全动操纵面模型中。利用这一规律,通过动响应试验的方法测量出全动操纵面系统中的库仑摩擦参数,并验证了这种方法的正确性。

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.