## 4 Analysis of the Factors Affecting on the Gathering Process and Self-Preservation of the STACER
### Influence of Acceleration on the Gathered State of STACER during Launching Process  
In an actual launch process, the STACER is fully packaged and fixed in place so as to avoid severe plastic deformation. However, it still undertakes a large acceleration in the launching process with an unstable state between spring layers. A problem occurred on the STACER during a successful deployment. A jamming of the mechanism occurred after the ground tests with extra accelerations. This is the reason for the acceleration study. In the simulation, the spring reel is fixed by both the top rod and storage bucket. The STACER experiences weight loss and overweight during the launch process. The contact conditions change over between the layers of the spring reel, which affects the stability and self-preservation performance of the STACER. Therefore, the purpose for analysis of self-preservation under launch accelerations is to provide a guidance for the installation of the STACER with a safe orientation. It is necessary to explore the effect of acceleration on the stability of the spring reel. From the initial state of the spring reel in a well gathered state, accelerations with different directions are applied to the spring reel. The acceleration of 100 G is selected according to various ground test results and is quite credible for the simulation. Accelerations in six different directions are applied to the spring reel, which are the positive and negative directions of the X-axis, Y-axis, and Z-axis, respectively. Figure 11a-d shows the simulation results corresponding to the accelerations at six directions. In the analysis of the six boundary conditions, the results are mainly divided into two categories, as shown in Figure 11b,c. When the acceleration directions are along the negative X-axis, positive and negative Y-axis, and Z-axis with 100 G, the spring reel stays stable, as shown in Figure 11b. When the acceleration direction is along the positive X-axis, which is parallel to the axis of rivet with a pressure, the spring reel cannot be completely gathered, as shown in Figure 11c. It can be concluded that the  
Figure 11: Influence of acceleration on the morphology and stress distribution of the spring reel with a friction coefficient of 0.1 between layers: (**a**) STACER model; (**b**) complete gathered state; (**c**) partial gathered state; (**d**) the morphology of the innermost circle; and (**e**) stress distribution. gaps between the layers of the spring reel lead to the partial gathered state of the STACER. When the acceleration is applied along the +X-axis, the morphology of innermost circle is observed, as shown in Figure 11d. The position of stress concentration occurs at the riveting point of the STACER, as shown in Figure 11e. The maximum stress is 1267 MPa, which is less than the yield strength of the spring reel material. As can be seen of the black line in Figure 12, there was a the force evolution with the acceleration of 100G applied along the positive direction of the X-axis. It is noteworthy that the fluctuation is the actual calculation result on the force evolution of the top rod with different friction coefficient and acceleration. It reflects the whole process of the force changes from the beginning to the end of the gathering process. In this case, the force of the top rod is significantly different from the other five acceleration conditions. The maximum force of the top rod is 34 N. Instead, the top rod is subjected to the trend with multiple peaks and valleys alternately under other five acceleration conditions. The maximum force is between 40 and 51 N, which is much higher than the maximum force with the acceleration along the direction of +X-axis. When the acceleration is along the positive direction of the X-axis, relative movement occurs between the layers of the spring reel, as shown in Figure 13a-d. The innermost layer near the top rod spreads outward and the gap between the layers gradually increases.