航天器振动试验中的动力吸振现象

振动环境试验是考验航天器中各分机力学品质的重要试验,分机适应力学环境的能力在设计阶段必须充分考虑。目前分机的力学环境条件往往是在考虑了一定的安全系数后,以分机安装处界面的加速度包络曲线给出的。然而一般来说,分机振动试验过程中的边界条件与分机实际工作状态的边界条件是不同的。具体地说就是在振动试验过程中分机通过试验转接托架与振动台面相连,实际工作状态是分机安装在安装件(卫星各舱板)上。由于试验转接托架与安装件的动力学特性不一样,根据多自由度弹簧质量阻尼系统的动力吸振原理,可以推出试验状态分机在固有频率处存在过试验现象。为了减少过试验对分机带来的危害,新的试验方法研究(加速度响应限幅控制、阻抗特性模拟法、限力技术等)已成为国内外航天工作者研究的热点。文章详细阐述了振动试验中动力吸振的机理及过试验产生的缘由。

The Dynamic Absorber Effect On Mechanical Vibrations Of Spacecraft

Vibration test is the main program to examine the mechanical property of space structure.The ability to survive the test is very important in the primary design of a spacecraft.The specification,namely,the envelope of the acceleration peaks of the flight environment,plus sometimes a known acceptable margin,is obtained between the mounting structure and the test article.In fact it is different in boundary conditions(bcs) between test and flight configurations.During a vibration test,the test article is usually attached to a very rigid fixture and is excited or driven along a single linear direction,with the structure being completely restrained along the other five degrees-of-freedom(dof).In the flight configuration,the test article is attached to a mounting structure that normally exhibits some flexibilities in all six dof in the frequency range of interest.Dynamic absorber effect of multiple dof introduce the overtesting phenomenon that occur at test article's resonance frequency.In irder to reduce the artificial overtesting phenomenon,more and more new approaches,include acceleration response limited,structural impedance simulation,force limit,etc.,are studied by aerospace researcher all the world.The reason about dynamic absorb effect and overtesting in vibration test is described in detail on this paper.