Browsing by Author "Langer, Martin"

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    Combining additive manufacturing and biomimetics for the optimization of satellite structures
    (2018-10) Vogel, Daniel; Geismayr, L.; Langer, Martin; Leslabay, Pablo; Schlickc, G.
    "Successful utilization of Additive Manufacturing (AM) in the space sector implicates two aspects: First, an understanding of the process inherent characteristics has to be developed, where the anisotropic behavior of material is of significant importance. Second, the part design methodology has to be adapted, since it is often coupled and limited to traditional shapes and production methods and thus prevent an exploitation of the full AM potential. In a research collaboration between the Technical University of Munich, the Instituto Tecnológico de Buenos Aires, and the Fraunhofer Research Institution for Casting, Composite and Processing Technology, the structural optimization of a microsatellite yielded in research in both areas. In this paper the evaluation of the Total Mass Loss (TML), Coefficient of Thermal Expansion (CTE) and tensile strength for the materials polyether-ether-ketone (PEEK) and Ti6Al4V, which are both relevant for space applications, will be reported. Tensile and dilatometer specimen with orthogonal placement on the build platform for all three printing directions were produced via Fused Deposition Modelling (FDM) for PEEK and laser powder bed fusion (L-PBF) for Ti6Al4V in accordance to national standards. Outgassing tests of the specimen show that the TML for both materials is below the limit of 1%. CTE values deviate 13% from the manufacturers’ specified mean value for injection molded PEEK. Mean tensile strength values for PEEK were 57% worse than the injection molded values specified by the manufacturer. Ti6Al4V samples showed no anisotropy and fitted the expected values for both, CTE and tensile strength. The overall results indicate the need for additional tests and safety factors when using additive manufactured PEEK for space applications. The second part of this paper presents a holistic design approach, composed of several already known methodologies. For the selection of suitable part candidates for AM specific redesign, different parts and assemblies in terms of manufacturability, economic feasibility and the potential of functional improvements were compared. For the subsequent part redesign, a biomimicry inspired design methodology in combination with AM design rules was applied, overcoming common thinking patterns. The approach was verified through a case study, where a star tracker’s housing was systematically redesigned. The new design includes an integrated thermal link, which helps to keep the commercial off the shelf (COTS) sensor at low temperatures during operation, and an integrated compliant mechanism for the fine adjustment of the sensor. Finally, the design was validated through thermal analysis in ESATAN-TMS and structural analysis in ANSYS."
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    Hardware in the loop and software in the loop testing of the MOVE-II CubeSat
    (2019-12) Kiesbye, Jonis; Messmann, David; Preisinger, Maximiliam; Reina Kiperman, Gonzalo Julián; Nagy, Daniel; Schummer, Florian; Mostad, Martin; Kale, Tejas; Langer, Martin
    "This article reports the ongoing work on an environment for hardware-in-the-loop (HIL) and software-in-the-loop (SIL) tests of CubeSats and the benefits gained from using such an environment for low-cost satellite development. The satellite tested for these reported efforts was the MOVE-II CubeSat, developed at the Technical University of Munich since April 2015. The HIL environment has supported the development and verification of MOVE-II’s flight software and continues to aid the MOVE-II mission after its launch on 3 December 2018. The HIL environment allows the satellite to interact with a simulated space environment in real-time during on-ground tests. Simulated models are used to replace the satellite’s sensors and actuators, providing the interaction between the satellite and the HIL simulation. This approach allows for high hardware coverage and requires relatively low development effort and equipment cost compared to other simulation approaches. One key distinction from other simulation environments is the inclusion of the electrical domain of the satellite, which enables accurate power budget verification. The presented results include the verification of MOVE-II’s attitude determination and control algorithms, the verification of the power budget, and the training of the operator team with realistic simulated failures prior to launch. This report additionally presents how the simulation environment was used to analyze issues detected after launch and to verify the performance of new software developed to address the in-flight anomalies prior to software deployment."