空间薄壁管结构瞬态温度场、热变形有限元分析

Transient Thermal-Structural Analysis of Space Structures Consisting of Thin Walled Tubes by FEM

对于辐射换热的薄壁杆件航天结构 ,为分析其在太空中不同时刻的姿态下的温度场和热变形 ,构造了一种相对自由度矩形管单元。其基本思想是从 2维非线性瞬态热传导方程出发 ,假设沿矩形管横截面上每边的温度为线性分布 ,用 4个角点的平均温度和温差来表示矩形管横截面上的温度分布 ,构造了一种 1维 2结点温度杆单元 ,该单元每个结点包含平均温度 ,上下面温差 ,左右面温差 3个自由度 ;在计算热变形时 ,此三个广义温度参数分别对应热轴力和 2个热弯矩载荷。经与三维有限元计算结果的比较 ,证明用该单元计算的矩形管温度场和位移场是可靠的。利用这种新型的薄壁矩形管单元和本文作者在其他文章中提出的薄壁圆管单元 ,可以对非线性换热条件下的复杂空间结构进行比较准确的温度场和热变形有限元分析 。

Space structures consisting of thin walled beams are s ub jected to incident solar heat flux and emit thermal energy by radiation. To anal yze the thermal-structural behavior of these structures, a rectangular tube ele ment with relative degrees of freedom for thermal analysis is proposed in this p aper. Temperature distribution along each edge of section of the tube is simulat ed as linear function, so that the temperature field in cross-section of the t ube can be expressed by the average temperature and temperature differences of t he four corners of the section. Finally, a two-node rectangular tube element w as presented for thermal analysis. Each node of these elements possesses three d egrees of freedom: the average temperature and two aberrations of temperature i n the cross-section. Therefore, in structural analysis, the initial node forces caused by thermal extension based on the present analysis will include not only axial force caused by average temperature, but also moments caused by temperatu re aberrations in the cross-section. Using the present rectangular tube element and the circular tube element presented in another paper, the transient thermal and structural response of space structure can be simulated accurately. Numeri cal calculations for the solar array with shadow demonstrate the effectiveness o f the present method.