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反射镜支撑结构通常需要具有一定的柔性来保证其面形精度,但这将引起结构固有频率降低,使得结构抵抗振动的能力下降。针对这一问题,开展了利用阻尼技术改善反射镜支撑结构动态性能的研究。建立了反射镜组件、相机机身和基础耦合的动力学模型,推导出系统传递函数、模态阻尼、振型等参数,并据此进行了理论分析。重点分析了在反射镜部分增加阻尼对镜体和机身振动传递特性的影响,并进一步从模态阻尼及振型分析等角度对这种影响产生的原因给予了解释。在理论分析的基础上,采用有限元法对所建立的更为精确的有限元模型进行了仿真研究。研究结果表明:在反射镜支撑结构中增加黏弹性阻尼元件可有效衰减反射镜组件的振幅和动应力,系统二阶频率处的振幅衰减达到6dB,一、二阶固有频率处的动应力衰减程度分别达到了28%和60%。由此可见,在反射镜支撑组件中加入阻尼元件是一种有效改善结构动力学性能的措施。
The mirror support structure usually needs to have some flexibility to ensure its surface accuracy, but this will cause the natural frequency of the structure to decrease, so as to reduce the ability of the structure to resist the vibration. In response to this problem, the use of damping technology to improve the dynamic performance of the mirror support structure research. The dynamic model of the mirror assembly, the camera body and the basic coupling is established. The parameters of the system transfer function, modal damping and vibration mode are deduced and analyzed theoretically. The influence of the increased damping on the mirror and body vibration transfer characteristics is analyzed emphatically, and the reasons for the influence are explained from the modal damping and mode shape analysis. On the basis of theoretical analysis, the finite element method is used to simulate the more accurate finite element model. The results show that the viscoelastic damping element can effectively attenuate the amplitude and the dynamic stress of the mirror assembly. The amplitude attenuation at the second-order frequency of the system reaches 6dB. The dynamic stress attenuation at the first and second-order natural frequencies Respectively, reached 28% and 60%. It can be seen that adding a damping element to the mirror support assembly is an effective measure to improve the structural dynamics.