含开口薄壁杆的空间结构热屈曲有限元分析

针对含开口薄壁杆件的大型空间柔性结构热屈曲问题,发展了一种包含翘曲自由度的二节点开口薄壁杆单元。该单元考虑了约束扭转与弯扭耦合效应,同时考虑了热应力对几何刚度阵的影响,可进行空间杆系结构的热屈曲分析。简单梁模型算例表明:该方法求得的各阶屈曲温度临界值和屈曲模态与AN SY S薄壳有限元解吻合较好;并且由于考虑了开口薄壁杆的特性,热首先引起杆件的弯扭耦合屈曲。对哈勃太空望远镜太阳帆板的简化模型进行了热屈曲分析,成功地解释了热使该太阳帆板发生扭转屈曲的原因。

Thermal buckling FEM of large space structures including thin-walled open section beams

Thermal buckling is a common problem for large flexible space structures consisting of thin-walled open section beams.A two-node thin-walled open section beam element was developed with a warping degree of freedom.This element is capable of analyzing restricted torsion and the coupled bending-torsional effect,moreover,the thermal stress is considered in the geometric stiffness matrix.The element can be used in thermal buckling analyses of space truss structures.The predicted critical buckling temperature and buckling modes for a simple model by using the beam elements are in good agreement with the finite shell element solution by ANSYS.The numerical solutions also show that thermal buckling with the bending-torsional mode will occur first if the characteristics of the thin-walled open section beam are considered.The cause of the torsional buckling observed on the Hubble Space Telescope solar arrays is explained by the present thermal buckling analysis.