平台罗经框架的模态计算与试验分析

Modal calculation and correlation analysis of the frame of a platform compass

平台罗经框架结构是惯性平台的主要部件之一,其动态特性将直接影响到平台系统各部件对振动环境的适应性.结构的动态特性信息可通过2种途径得到,模态计算和模态试验.分别通过计算和试验2种方法得到了外框架的模态结果,并且对模态相关性分析的理论进行了探讨分析,得到了外框架结构的模态相关性结果,此过程是进行下一步模型修正以及动响应分析的基础.通过分析计算可知,模态计算比试验得到的固有频率要高,在前8阶模态中,除了第5阶和第8阶相关性稍微差一点,而其他的振型相关性比较明显.提出了提高结构系统的动态性能改进方法,为今后的改进和设计提供了理论依据.

Frame structures are one of the most important factors influencing performance of a platform compass. The dynamic characteristics of frame structures directly affect the adaptability of the system to vibrating environments. These characteristics could be derived analytically and/or experimentally. The modes of vibration of frame structures were obtained with both approaches separately. The results were correlated using correlation analysis. That process became the basis for a finite element modification and dynamic response analysis. The natural frequen- cy, when derived by mode calculation, is higher than that found by testing. The correlation is more obvious, except the low correlation between calculation mode and test mode of the 5th-order and 8-order in the first 8 order modes. Some methods and suggestions for improving the structural system＇s dynamic properties are proposed. A basis for future improvements to the platform compasses is provided.