基于模态分析的单轴旋转惯性导航系统结构优化

Structural optimization of single-axis rotary inertial navigation system based on modal analysis

针对单轴旋转调制惯性导航系统结构动刚度低的问题,以模态仿真分析为基础对系统结构进行优化改进。基于无质量弹性单元等效滚动轴承的方法,利用经验公式计算轴承等效刚度,并引入转子动力学合理表征系统的旋转行为,利用有限元分析软件ANSYS实现了系统模态的高可信度仿真分析。以提高系统一阶模态频率为设计目标,通过结构性能缺陷识别的方法确定优化方向,对结构薄弱点进行改进设计,将系统结构基频从36 Hz提高到74 Hz。最后,开展模态试验验证。试验结果表明,仿真与试验的符合度优于90%,优化后的系统在0~60 Hz的扫频范围内无明显振动响应。

Aiming at the problem of low dynamic stiffness in single-axis rotary modulation inertial naviga- tion system, the structure optimization is carried out based on modal simulation analysis. The rolling bearings are modeled equivalently with elastic element, and its stiffness value is calculated using empirical formula. Then the theory of rotor dynamics is introduced to characterize the rotating mechanical property. High- reliability modal simulation is realized using FEA software ANSYS. Taking increasing the system＇s first-order modal frequency as the design target, the optimization direction is confirmed according to modal analysis and mechanism defect identification, the supporting structure is improved by adopting reinforced measurement, and the system＇s fundamental frequency is increased from 36 Hz to 74 Hz. At last, modal experiment verifi- cation is carried out, and the results show that the conformity between simulation and test is above 90%, and system mechanism acquires good dynamic adaptability within sweep range of0-60 Hz after optimization.