# Metal Additive Manufacturing for Satellites and Rockets
## 5 Structural Components  
Structural parts of spacecraft have to show sufficient mechanical properties, combined with the necessity to withstand harsh conditions, especially regarding outer parts of satellites, rockets, etc. Metal 3D printing in general can be used to combine these necessities with the possibility to build lightweight structures and possibly even to use a modular design to enable change and service of single components [84]. Further, it can make fabrication quite fast, which was demonstrated by [PERSON] et al. who used direct metal laser sintering to design, optimize, prepare, test, and finally launch different AlSi\({}_{10}\)Mg components for a satellite within half a year [85; 86; 87]. The process included mass optimization by a bionic design of the parts, optimized in several cycles.  
Important parts of the construction of satellites are metal brackets connecting the satellite body with reflectors and feeder facilities. [PERSON] et al. performed a thermoelastic stress analysis on such brackets, produced by electron beam melting from a titanium-based alloy [88]. This analysis was applied to investigate the difference between CAD constructed and printed components. The method applied for this investigation, thermoelastic stress analysis, is based on thermal motions in a material due to dynamical load at a suitable frequency, made visible by a thermocarea. Results of the experimental investigation are depicted in Figure 7, showing the stress concentration in Figure 7a and opposite stress components on the upper and lower curvature in Figure 7b.  
Figure 7: Thermoelastic stress analysis results revealing the location and the sign of the stress concentrations in a metal bracket for satellites. Reprinted from [88], with permission from Elsevier. (**a**) Amplitude image (digital levels); (**b**) phase image, the colors represent the range (\(-180^{\circ}\), +180\({}^{\circ}\)).  
[PERSON] et al. reported on vibration tests performed on AlSi\({}_{10}\)Mg manufactured by direct metal laser melting to form a lightweight satellite structure based on lattice sandwich panels, with a mass reduction of more than 50% as compared to conventionally produced satellite structures [89]. Similar mass reductions of around up to 50% can also be found for the previously applied laser beam melting technology in the space industry, often working with aluminum alloys. [PERSON] et al. compared laser beam melting of the often used AlSi\({}_{7}\)Mg\({}_{0.6}\) with a new high-strength alloy named Scalmalloy(r) and developed the optimized parameters for the additive manufacturing process, resulting in better fatigue performance of Scalmalloy(r) in alternated traction compression up to 10\({}^{4}\) cycles and very low porosity rate, making it a promising material for the space industry [90].  
It should be mentioned that while these results are often highly promising, space industry companies have to ensure that structural components will not be damaged under the extreme conditions in space, so that extended tests are performed before additively manufactured structural components are really sent into space, and only few of such components have been used in satellites, etc. [91; 92; 93]. This is different for elements with lower requirements according their mechanical properties, such as antennas.