Space Station Freedom Module to Truss System Thermal/Structural Analysis

A thermal/structural analysis of the Module to Trass System (MTS) of the Space Station Freedom (SSF) was performed. Its objective was to find the temperature distributions and temperature gradients in the structure in order to evaluate thermal stresses and deflections in the truss members caused by solar loads and by shadowing of the truss members by other segments of the Space Station, as it moves around the orbit. Temperatures in the truss components depend on the position and orientation of the Space Station in the orbit with respect to the Sun and Earth.

Because of the large number of surfaces, thermal-structural analysis of a truss structure typically requires a large amount of effort and computer resources. In order to reduce this, a technique of thermal/structural analysis was developed and applied. A SINDA thermal finite difference model and a TRASYS radiation interchange model of the truss were generated automatically from a NASTRAN finite element structural model. The entire process of model development, analysis and thermal/structural data transfer was automated, minimizing analysis time as well as possibility of errors. The primary purpose of the MTS analysis was to develop and demonstrate this technique.

The thermal analysis was performed for two extreme scenarios, corresponding to two values of solar beta angle. The temperature distribution at one orbital point was chosen to perform the NASTRAN structural finite element analysis and to illustrate how to determine the thermal stresses and deflections.