美国SMAP卫星失效的一个可能性分析

A possible analysis for failure of U.S. SMAP satellite

美国主被动土壤水分监测卫星(Soil Moisture Active Passive, SMAP)是目前唯一搭载偏心旋转复合材料环形桁架天线的在轨卫星,但在轨仅工作数月便出现无法修复的雷达故障,损失惨重,故障原因至今尚未查明.基于复合材料圆柱壳等效模型,本文研究了考虑横向激励和参数激励共同作用下超大型复合材料环形桁架天线在偏心旋转状态的内共振特性和非线性动力学问题,从非线性动力学角度提出了一种SMAP卫星失效的可能性分析,也为我国研究此类大型可展卫星天线提供了理论参考.利用Donnell薄壁剪切变形理论及Hamilton原理建立偏心旋转复合材料层合圆柱壳的非线性偏微分方程,应用Galerkin离散导出耦合非线性常微分方程.通过Campbell图得到发生1:2内共振的参数条件后,进一步研究了偏心率和几何参数对偏心旋转复合材料层合圆柱壳内共振条件的影响.随后,利用多尺度法得到了1:2内共振和1/2次谐波共振情况下的四维非线性平均方程.通过数值仿真,发现在一定的横向激励和温度参数激励作用下,处于偏心旋转状态的超大型环形桁架天线等效模型发生大振幅混沌运动.这为解释SMAP卫星雷达失效提供了一种可能性.

The Soil Moisture Active-Passive(SMAP) satellite is the only satellite with a large deployable space eccentric rotating ring truss antenna clamped along a generatrix and rounding a parallel axis. However, the active radar of SMAP satellite stopped working within months of its launch. What are the reasons leading to so dramatic consequences? It is a possibility that the satellite damage is caused by vibration. In this paper, the nonlinear breathing vibrations of the large deployable space eccentric rotating composite laminated ring truss antennas with the large radius are studied from a theoretical analysis of view. Referring to the equivalent model of the continuum circular cylindrical shell clamped along a generatrix, we propose a dynamic model of the eccentric rotating composite laminated circular cylindrical shell subjected to the lateral and the temperature excitations. Considering an eccentric rotating composite laminated circular cylindrical shell clamped along a generatrix and rounding a parallel axis, the nonlinear partial differential governing equations of motion are established by using Donnell thin shear deformation theory, von Kármán-type nonlinear relation and Hamilton’s principle. The nonlinear ordinary differential governing equations of motion are obtained by using Galerkin discretization. Based on the theoretical model, the nonlinear breathing vibrations of the equivalent model are studied for the SMAP satellite antenna subjected to the lateral and the temperature excitations for the first time in this paper.Firstly, the effects of different parameters on the toggle condition of 1:2 internal resonance are studied. The effects of the radius and the eccentricity ratio on the natural frequencies are not obvious for the eccentric rotating composite laminated circular cylindrical shell. Furthermore, it is also found that the influence of the thickness and the eccentricity ratio on the resonant rotating speeds cannot be ignored for the eccentric rotating composite laminated circular cylindrical shell. Then,based on the case of 1:2 internal resonance and principal parametric resonance-1/2 subharmonic resonance, the parametric excitation T is selected as the controlling parameter to discover the nonlinear breathing vibrations of the eccentric rotating composite laminated circular cylindrical shell. The periodic and chaotic motions of the equivalent model for the SMAP satellite antenna are found when the rotating speed corresponds to the internal resonant point at the certain excitations for different lateral and temperature excitations. Therefore, the chaotic motions of the SMAP satellite antenna occur under the combined action of temperature parameter excitation and lateral excitation in the space environment.According to the research results of this paper, the active radar of the SMAP satellite may be damaged by severe nonlinear vibrations. We reasonably speculate that the failure of the active radar for the SMAP satellite antenna is caused by the nonlinear vibrations in 1:2 internal resonance. Thus, this paper not only provides a possible analysis for the failure of the SMAP satellite, but also provides the theoretical guidance for study of similar ring truss antennas. This research has important theoretical significance and engineering value.