Structure & Mechanisms

BayernSat is essentially a cube, and additional parts such as antennas, solar panels or launch adapters are attached to it.
The cube, also called main bus, is formed by a framework construction together with two integrated panels.

Figure 1: Basic structure of BayernSat

Sandwich panels will be mounted on the open parts of the framework construction; they, just as the integrated panels, will carry the instruments. This concept is also called body mounting concept. The launch adapter forms a rotationally symmetrical shell, which has been tailored to the required form. On the lower end, the adapter blends into the separation ring, a device which is used to separate the satellite from the launcher. The antenna has a pivoted mounting, and is actuated by a motor inside the satellite via a lever system. There are more antennas on the outside of the satellite, which make possible direct communication (not via Artemis).

Figure 2: BayernSat with spread-out solar panel

The two outer solar panels are collapsible; they are linked with the solidly mounted middle panel via springs. In the launching configuration these panels are kept in their position by so-called hold-downs. After the release, the springs open the panels and and they are fastened securely in this position because of their specific arrangement and form.

Figure 3: BayernSat in launching configuration

In addition to the CAD model, a FEM model was implemented to examine this configuration. It describes all the decisive parameters of the BayernSat configuration, starting from dimensions, materials, down to the mass of the instruments. The model is also able to map all states such as folded or unfolded solar panels or different antenna angles.

Figure 4: FEM model of BayernSat

The model was tested for the normal loads such as the load during the launch. Loads of more than 10g are not unusual. It was proven however that the configuration endures these loads; there is even room for further weight reduction. Apart from static loads, a modal analysis was carried out. As a result of the small dimensions of BayernSat as well as the rigid structures, all the oscillation frequencies are within the given limits.

Two modes are given as an example for natural oscillation.
Figure 5 shows one oscillation mode of the antenna. This mode is the first mode (i.e. the lowest frequency) of the whole configuration. This oscillation can be absorbed by adequate measures.

Figure 5: Oscillation mode of the antenna

Figure 6 shows the first significant mode of the configuration, i.e. not just local components are oscillating, but the whole satellite. These modes are decisive for the evaluation of the structure.

Figure 6: First significant mode of oscillation

	Additional Information Structure
	Description of the Structure (in German)