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In case of electric vehicles (EV) powered by lithium ion traction batteries (LIB), remanufacturing processes nbecome increasingly important due to their rising market share and valuable raw materials. LIB can account for up to 40% of the total EV cost. Often, only a small portion of the cells are significantly degraded when the usable battery capacity falls below 80%, which is currently considered the standard end-of-life criterion. However, in order to enable efficient remanufacturing, novel battery design principles are required. This paper discusses the requirements, opportunities and challenges of future remanufacturing processes of LIBs down to the cell level using a battery system of a commercial vehicle as an example. It gives an overview of the current state-of-the-art manufacturing processes of battery systems and shows the developed overall remanufacturing process including condition assessment, disassembly and reassembly. Subsequently, requirements on future designs are discussed. The state-of-the-art of EV batteries is evaluated based on these requirements to determine where incompatible connections such as welded contacts or adhesive joints conflict with remanufacturing design principles.
This work describes why additive manufacturing is a key technology for efficient design iterations and rapid production ramp-up with large-scale manufacturing technologies. Laser cutting, injection moulding and folding were used to increase the production capacity of face shields for health care workers during the COVID-19 pandemic. We applied systematic learnings from the iterative processes used for additive manufacturing to these large-scale manufacturing technologies and the respective face shield designs. In cooperation with medical experts, structural and functional design requirements of face shields were identified and are described in detail in this work. The regulatory design requirements according to EN 166 are introduced, which were considered to receive a CE certification for three of the presented designs. The employed manufacturing techniques are specified and the respective implications on the design solutions are discussed. The paper concludes with a summary of the production initiative at the research campus ARENA2036 with a total output of over 13 000 face shields from April to June 2020, which were distributed internationally.
Ziel der vorliegenden Arbeit ist die Entwicklung eines messtechnischen Verfahrens, um prozessbedingte Variationen der Faserarchitektur textiler Preforms im Entwicklungsprozess von Bauteilen aus Faser-Kunststoff-Verbunden berücksichtigen zu können. Anhand mechanischer Prüfreihen von geflecht- und gelegeverstärkten Verbundwerkstoffen können klare Wirkzusammenhänge zwischen visuellen Textilmerkmalen und den mechanischen Eigenschaften identifiziert werden. Schwerpunkt der Untersuchungsreihen sind Auswirkungen von Lücken, Ondulationen und Streuungen des Faserwinkels auf die Zug- und Druckeigenschaften kohlenstofffaserverstärkter Kunststoffe. Die Erkenntnisse fließen in die Entwicklung eines optischen Messsystems zur 3D-Preformanalyse ein, welches mittels grauwertbasierter Bildverarbeitung die vollflächige Texturanalyse komplexer, dreidimensionaler Oberflächen ermöglicht. In der Arbeit werden zuletzt Anwendungspotenziale der detaillierten Faserarchitekturanalyse zur Optimierung von Fertigungsprozessen und zur Bauteildimensionierung vorgestellt.
Carbon fiber reinforced plastics (CFRP) allow to redesign well established metallic structures like manipulators in order to decrease their weight and to increase their level of performance. This task can only be successful, when the CFRP-design process does not copy the metallic structure, but solves the underlying functions in a new way. The present study shows, how an I-beam steel manipulator was transferred to a braided design with hollow cross sections and locally adapted material properties. Step by step we show, how to define the manipulator’s functions and mechanics and how they can be considered with a braided CFRP-structure. This includes analytical pre-design as well as detailed finite element method (FEM) design. A mechanical testing program was performed in order to measure input-values for the numerical calculations on coupon-level and validate the simulation on system level. Static and dynamic tests of the CFRP-manipulator showed that it fulfils all requirements to be certified for sale. Therefore, the braiding process for commercial production was investigated for two machine setups and the state of serial production was reached. The braided CFRP-manipulator is 70% lighter than the steel reference and has increased handling properties because of locally adapted material properties.
Scope of the presented work is a detailed comparison of a macroscopic draping model with real fibre architecture on a complex non-crimp-fabric preform using a new robot-based optical measurement system. By means of a preliminary analytical process design approach, a preforming test centre is set up to manufacture dry non-crimp-fabric preforms. A variable blank holder setup is used to investigate the effect of different process parameters on the fibre architecture. The real fibre architecture of those preforms is captured by the optical measurement system, which generates a three-dimensional model containing information about the fibre orientation along the entire surface of the preform. The measured and calculated fiber orientations are then compared with the simulation results in a three-dimensional overlay file. The results show that the analytical approach is able to predict local hot spots with high shear angles on the preform. Macroscopic simulations show a higher sensitivity towards changes in blank holder pressure than reality and limit the approach to precisely predict fibre architecture parameters on complex geometries.
The effect of the cover factor on the in-plane mechanical properties of biaxial and triaxial braided carbon fiber composites is investigated. Low braid coverage occurs if the mandrel circumference exceeds a specific length, so that gaps occur in between the different yarn systems.
Braids are manufactured on different mandrel sizes with a braid angle of ±45°. The cover factor is calculated analytically and measured by means of gray scale analysis of scanned samples. A new analytical model is presented which allows for calculating the cover factor of triaxial braids in good approximation with real results, taking into account the off-centered alignment of the axial yarns. Tensile and compression test results are presented for the thermoset resin systems EPIKOTE MGS® RIM 235 and HexFlow® RTM6. The results show that there is a significant influence of decreased cover factors on the mechanical properties, especially in case of triaxial braids tested in axial direction. Micro computed tomography images based on synchrotron radiation reveal that low coverage leads to an increased fiber undulation of the axial yarns, which mainly determine the mechanical properties of triaxial braids. An influence of the different resin systems is observed for matrix-dominated properties of biaxial braids, where the composite failure strain is in the range of neat resin failure strain.
Breaking down the cost structure of state-of-the-art CFRP part shows that a major share of the costs is caused by labor and equipment as well as process energy consumption.
Therefore, the main goal of the EU funded FP7 project LOWFLIP (Low Cost Flexible Integrated Composite Process) has been the reduction of these costs by introducing new technologies into CFRP production processes.
The LOWFLIP concept focuses on three main aspects:
• Development of a new out-of-autoclave (OOA) prepreg system with snap cure capabilities.
• Development of a direct 3D placement technology for plies and tapes.
• Development of energy efficient and fast heating toolings.
The main content of this paper is detailed information on a novel direct 3D prepreg layup process for automated production of large-scale fiber reinforced parts of small and medium lot sizes. The advanced ply placement process, which is able to drape and compact unidirectional prepreg tapes with currently up to 300 mm ply width directly into a double curved tooling, is being introduced. Two large-scale demonstrator parts from the transport and aerospace sector will be presented. Experiences gained during prototype manufacturing will be reflected and benchmarks of the equipment are presented.
A successful application of braiding technology for the manufacturing of an industrial product is shown on the example of a carbon fiber-reinforced plastic (CFRP) manipulator. Due to its lightweight design, the CFRP system offers highly ergonomic advantages for the worker compared to the previously available steel version. In the course of the braided manipulator design, braid-specific manufacturing options were used to improve bending and torsion stiffness by combining design aspects and fiber architecture variations. It is also shown how braid-related manufacturing constraints can be overcome by additional subsystems, eg, to realize strongly curved part geometries. Finally, a process of the mechanical testing procedure for the whole system is presented which follows the classical building-block approach used for the validation of aeronautical structures.
The energy absorption capacity of braided composite frames under bending loads was studied by conducting quasi-static four-point-bending tests. As specimen geometry C-shaped frame segments where chosen which show the typical failure behaviour of frames with open cross section, such as local buckling and crippling. The braiding manufacturing process offers the possibility to influence the fracture mechanics by a local hybridization of the braider yarns. Different hybridization concepts were investigated to identify design principles for braided frame structures with enhanced energy absorption capacity. The test results show that the post-failure energy absorption of braided frame segments can be significantly increased by a local modification of the braid architecture.
The Industrial Metaverse (IM) is an upcoming topic for companies and offers new possibilities to digitalize and optimize their business processes together with AI capabilities. In the production domain, the Industrial Metaverse is a step towards the vision of predicting factory behavior for optimization purposes. A central challenge is a complete factory model necessary as the base to predict its behavior. Therefore, the IM approach is promising to build and contain this model out of available single Digital Twins of factory parts. Consequently, an IT target landscape is required to build an Industrial Metaverse for Digital Twins. This paper evaluates different design pattern options for an industrial IT architecture reference implementation of an IM that companies can use in current IT landscapes. It also proposes a high-level roadmap towards the proposed target IT architecture of an IM.
