Study On Dynamic Characteristics Of Spacecraft Jointed Solar Arrays

Modern spacecraft are usually equipped with solar arrays to provide the required energy for the daily work of the spacecraft.Due to the limitations of launch and transport devices,spacecraft solar cells are often designed in a multi-plate jointed,foldable form.Such solar cell arrays often have characteristics such as light weight,large span,and low stiffness,and their inherent characteristics are manifested as low frequency,dense mode shapes.This article mainly analyzes the inherent characteristics of spacecraft solar arrays.Taking a typical solar array as an example,the Rayleigh-Ritz method which based on the energy principle is used to analyze structure inherent characteristics.Firstly,the energy equation of the typical solar array is established.The Lagrange multiplier is used to describe the internal displacement matching conditions and the external boundary conditions of the structure.The frequency equation of the structure is deduced by the Rayleigh-Ritz method.Through specific examples,the natural frequency of the structure and the modal function of the lower degree of freedom analysis are calculated by numerical methods.The numerical simulation results are compared to verify the correctness of the method.The analysis of the results shows that the higher the truncation order of the modal function is,the closer the result is to the numerical simulation result,which proves the convergence of the calculation method.At the same time,the analytical form of the modal function can describe the coupled bending and torsional vibration modes of the structure,and provide favorable conditions for dynamic analysis of structures such as nonlinear vibration and controller design.Not only this,but also this method of calculation is not affected by the number of hinges between panels and the position of hinges are limited.By changing the stiffness of the hinge to change the inherent characteristics of the structure,we can see that the stiffness of the hinge will only affect the first 6 natural frequencies of the typical solar array,and will not affect the other high-order natural frequencies of the structure.Similarly,the calculation and analysis show that the flexural rigidity of the plate itself only changes the high-order frequency of the structure and does not affect the low-order frequency of the structure.Analyze the 1st vibration mode,and calculate that the most effective way to increase the fundamental frequency of the structure is to increase the stiffness of the left end hinge.The lumped masses are loaded on the 4th,5th,and 6th plates of the structure,and the structural frequencies and modes are rearranged.The calculation and analysis show that when the concentrated masses are uniformly loaded on the above three plates,it has a good effect on the rearrangement of the structure frequency and modes.At last,the change law of the natural frequency of the structure in the thermal environment is analyzed.The calculation and analysis show that the change of the temperature will have a greater impact on the low-order frequency of the structure,while the high-order frequency is basically not affected by the temperature.In general,however,an increase in temperature will cause the structure to expand and its stiffness will decrease,reducing the natural frequency of the structure.