超单元应用中的关键问题研究

A Study of the Key Problem in the Application of Superelement

航天相机结构复杂,相应的有限元模型大,计算机分析效率低,甚至无法求解。为缩减模型自由度,提高计算机求解效率和能力。采用超单元技术划分相机有限元模型,利用部件模态综合法降低系统阶数;着重研究超单元在MSC.Patran中创建时和在MSC.Natran中分析时所遇到的各种关键问题,分析错误产生的原因,提出相应的解决措施;并通过一大型算例验证了超单元模型的准确性。分析结果表明:超单元法与整体有限元分析法比较,求解的前10阶固有频率误差小于4%,而计算时间仅为原来的1/2。超单元法很大程度上缩减模型自由度,提高计算机解算能力,节省计算时间。

Space cameras have complicated structure and correspondingly large FE model. The efficiency of computer analysis is low, even the solution can＇ t be realized. To reduce the freedom of the model and improve the solution efficiency and ability of computers, this article uses superelement technology to build a finite element model of the camera and uses modal synthesis method of substructure to lower the dimensions of the system. The key problems of the creation of superelement in MSC. Patran and the analysis in MSC. Nastran are primarily studied. The reason of causing mistakes is analyzed and the measures of solution are given. A large - scale example verifies the accuracy of superelement model. The analysis results show that the superelement method contrasting to the whole finite element method, the first ten orders normal frequency errors are less than 4%, the calculating time is shortened to 1/2. The superelement method largely reduces the freedom of models, improves the solution ability of computers and saves the time of calculations.