Structural Analysis of Regular Polygon Thin-Walled Structures for Load-Bearing Systems in Space Launch Applications: A Satellite Dispenser Case Study

Sammanfattning

The increasing use of satellite constellations creates a need for dispenser systems capable of carrying and deploying multiple spacecraft efficiently. Conventional cylindrical dispensers may require additional interface structures when spacecraft mounting points are located far from the cylindrical surface. This work investigates whether a polygonal dispenser structure can provide a structurally feasible alternative by placing the load-carrying structure closer to the spacecraft interfaces. The study has two main objectives: to identify the spacecraft sizes and configurations for which a polygonal dispenser is most suitable as an alternative to a cylindrical dispenser, and to determine how such a structure must be adapted relative to a cylindrical reference design in order to satisfy the structural requirements defined by the launch vehicle provider. The study is divided into three separate parts: an initial study, a parametric study, and a concept study. The initial study examines the structural behaviour of cylindrical and polygonal thin-walled structures without attached spacecraft, focusing on stiffness, eigenfrequencies, and buckling. The parametric study evaluates the influence of geometric parameters, such as the number of sides, radius, corner radius, and launch vehicle adapter length, for different spacecraft configurations. Finally, a selected polygonal configuration is further investigated and assessed against structural requirements for stiffness, static strength, and buckling. The results show that polygonal cross-sections can provide advantages in global bending stiffness, particularly for slender configurations with fewer sides. However, their performance is limited by the flexibility of the flat faces, especially for less slender configurations. Increasing the corner radius or introducing face curvature reduces the effective flat-face span, improves local stiffness, and reduces stress concentrations. A four-sided dispenser with one tier of medium-sized spacecraft was selected for the concept study. Under the same modelling assumptions as the cylindrical reference, the final polygonal concept satisfied the considered stiffness, strength, and buckling requirements after introducing face curvature, local laminate reinforcement, and additional stiffening at the upper interface. Although the concept increased the mass relative to the cylindrical reference structure alone, it may reduce the need for additional interface components. The results indicate that polygonal dispensers could be advantageous for selected configurations, particularly when reduced system complexity is prioritised.