非线性连接结构对一个典型卫星频率漂移的影响

Effect of nonlinearities in the joints on the amplitude-frequency response of a typical satellite structure

文章针对一个典型的卫星桁架结构建立了三自由度运动模型,分别引入间隙非线性和Iwan模型描述了非线性连接结构;利用数值方法研究了系统的频率漂移,讨论了间隙大小、预紧力(重力)、系统阻尼、随机间隙及Iwan模型的参数对频率漂移的影响;对比了两种非线性连接结构下系统频率漂移的特点。研究表明,间隙结合预紧力条件可令结构呈现"硬弹簧-软弹簧"特性的频率漂移,迟滞和间隙两种非线性引起的频漂在幅频曲线上表现出不同的特点。

For the system’s joints with a typical satellite truss structure and with a 3-DOF kinematic model,with gap and hysteresis nonlinearity described by the Iwan’s model,the frequency response is studied,and the two types of responses caused by the two kinds of nonlinearity are compared.The effects of the gap size,the preload（gravity）,the system damping ratio,the random gaps,and the parameters of the Iwan’s model on the nonlinear response are discussed.It is found that the gap in the joints under a preload condition can cause the ＂hardening-softening spring＂ frequency-shift phenomenon for a particular satellite structure,and the ＂frequency-shift＂ in frequency response curves obtained by the two types of nonlinearity shows different characteristics.