机载光电平台内框架刚度及模态有限元分析

Finite Element Modality and Stiffness Analysis of Airborne Electro-optical Platform Inner-gimbal

机载光电平台采用四框架二轴结构,它克服了二框架结构不能垂直对地跟踪的缺点,并提高了跟踪精度,随着精度的提高对框架的要求越来越高。应用有限元模态分析理论,对平台内框架的动态特性进行研究。在UG平台建立内框架三维实体模型,并对框架结构进行合理的简化。通过Patran有限元分析软件前后处理功能对框架采用合理单元进行网格划分,并建立有限元模型。计算出其前10阶固有频率和振型,根据计算的结果找出其结构的薄弱环节,提出改进方案并重新分析。另外,采用新型铝基复合材料以达到提高框架刚度和谐振频率从而达到提高整个平台精度的目的。最后对比三种分析的结果选出最优方案。

The airborne electro - optical platform adopts the structure of two - axis and four gimbals. It not only gets over the defect that two gimbals structure can not achieve vertical track to the ground , but also greatly enhances the track accuracy. With the increased accuracy , the requirement on the gimbal will be higher and higher. The theory of finite element modality analysis is applied to research dynamic characteristics of platform inner - gimbal. Three dimensional entity model of inner - gimbal is built on the platform of UG and is simplified reasonably . We select the reasonable element to plot the mesh by the software named patran with the strong functions of preprocessor and postprocessor and build the finite element model. The 10 extended natural frequency and model shape of the gimbal are worked out and by analysing the results, some weak components are found and some suggestions for the improvement are proposed. In addition, we adopt new aluminum composite material to analyse the gimbal in order to improve the stiffness and resonant frequency of the framework thus improving the accuracy of the whole platform. Finally, by comparing three results the optimum project is selected.