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Start date: 2019Institute: search.filters.UBSInstitut.Fraunhofer Institut für Produktionstechnik und Automatisierung (IPA)Publication Type: search.filters.UBSTyp.ZeitschriftenartikelSubject: search.filters.subject.620

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    Enzyme-assisted circular additive manufacturing as an enabling technology for a circular bioeconomy : a conceptual review
    (2024) Protte-Freitag, Kristin; Gotzig, Sophia; Rothe, Hannah; Schwarz, Oliver; Silber, Nadine; Miehe, Robert
    Additive manufacturing (AM) is a decisive element in the sustainable transformation of technologies. And yet its inherent potential has not been fully utilized. In particular, the use of biological materials represents a comparatively new dimension that is still in the early stages of deployment. In order to be considered sustainable and contribute to the circular economy, various challenges need to be overcome. Here, the literature focusing on sustainable, circular approaches is reviewed. It appears that existing processes are not yet capable of being used as circular economy technologies as they are neither able to process residual and waste materials, nor are the produced products easily biodegradable. Enzymatic approaches, however, appear promising. Based on this, a novel concept called enzyme-assisted circular additive manufacturing was developed. Various process combinations using enzymes along the process chain, starting with the preparation of side streams, through the functionalization of biopolymers to the actual printing process and post-processing, are outlined. Future aspects are discussed, stressing the necessity for AM processes to minimize or avoid the use of chemicals such as solvents or binding agents, the need to save energy through lower process temperatures and thereby reduce CO2 consumption, and the necessity for complete biodegradability of the materials used.
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    Optimization of disassembly strategies for electric vehicle batteries
    (2021) Baazouzi, Sabri; Rist, Felix Paul; Weeber, Max; Birke, Kai Peter
    Various studies show that electrification, integrated into a circular economy, is crucial to reach sustainable mobility solutions. In this context, the circular use of electric vehicle batteries (EVBs) is particularly relevant because of the resource intensity during manufacturing. After reaching the end-of-life phase, EVBs can be subjected to various circular economy strategies, all of which require the previous disassembly. Today, disassembly is carried out manually and represents a bottleneck process. At the same time, extremely high return volumes have been forecast for the next few years, and manual disassembly is associated with safety risks. That is why automated disassembly is identified as being a key enabler of highly efficient circularity. However, several challenges need to be addressed to ensure secure, economic, and ecological disassembly processes. One of these is ensuring that optimal disassembly strategies are determined, considering the uncertainties during disassembly. This paper introduces our design for an adaptive disassembly planner with an integrated disassembly strategy optimizer. Furthermore, we present our optimization method for obtaining optimal disassembly strategies as a combination of three decisions: (1) the optimal disassembly sequence, (2) the optimal disassembly depth, and (3) the optimal circular economy strategy at the component level. Finally, we apply the proposed method to derive optimal disassembly strategies for one selected battery system for two condition scenarios. The results show that the optimization of disassembly strategies must also be used as a tool in the design phase of battery systems to boost the disassembly automation and thus contribute to achieving profitable circular economy solutions for EVBs.
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    Comparison of the temperature, radiation, and heat flux distribution of a hydrogen and a methane flame in a crucible furnace using numerical simulation
    (2024) Mages, Alexander; Sauer, Alexander
    Sustainable technologies to replace current fossil solutions are essential to meet future CO2 emission reduction targets. Therefore, this paper compares key performance indicators of a hydrogen- and a methane-flame-fired crucible furnace with computational fluid dynamics simulations at identical firing powers, aiming to fully decarbonize the process. Validated numerical models from the literature were used to compare temperatures, radiation fields, radiation parameters and heat transfer characteristics. As a result, we observed higher combustion temperatures and a 19.0% higher fuel utilization rate in the hydrogen case, indicating more efficient operating modes, which could be related to the increased radiant heat flux and temperature ranges above 1750 K. Furthermore, higher scattering of the heat flux distribution on the crucible surface could be determined indicating more uneven melt bath temperatures. Further research could focus on quantifying the total fuel consumption required for the heating up of the furnace, for which a transient numerical model could be developed.
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    Design of fiber-composite/metal-hybrid structures made by multi-stage coreless filament winding
    (2022) Mindermann, Pascal; Müllner, Ralf; Dieringer, Erik; Ocker, Christof; Klink, René; Merkel, Markus; Gresser, Götz T.
    The methods presented in this study assist in fabricating load-bearing structures with high mass-specific mechanical performance at various scales. Possible applications include primary and secondary structures in engineering, architecture, automotive, or aerospace industries.Additive manufacturing processes, such as coreless filament winding with fiber composites or laser powder bed fusion with metals, can produce lightweight structures while exhibiting process-specific characteristics. Those features must be accounted for to successfully combine multiple processes and materials. This hybrid approach can merge the different benefits to realize mass savings in load-bearing structures with high mass-specific stiffnesses, strict geometrical tolerances, and machinability. In this study, a digital tool for coreless filament winding was developed to support all project phases by natively capturing the process-specific characteristics. As a demonstration, an aluminum base plate was stiffened by a coreless wound fiber-composite structure, which was attached by additively manufactured metallic winding pins. The geometrical deviations and surface roughness of the pins were investigated to describe the interface. The concept of multi-stage winding was introduced to reduce fiber–fiber interaction. The demonstration example exhibited an increase in mass-specific component stiffness by a factor of 2.5 with only 1/5 of the mass of a state-of-the-art reference. The hybrid design approach holds great potential to increase performance if process-specific features, interfaces, material interaction, and processes interdependencies are aligned during the digitized design phase.
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    Model-based biomechanical exoskeleton concept optimization for a representative lifting task in logistics
    (2022) Schiebl, Jonas; Tröster, Mark; Idoudi, Wiem; Gneiting, Elena; Spies, Leon; Maufroy, Christophe; Schneider, Urs; Bauernhansl, Thomas
    Occupational exoskeletons are a promising solution to prevent work-related musculoskeletal disorders (WMSDs). However, there are no established systems that support heavy lifting to shoulder height. Thus, this work presents a model-based analysis of heavy lifting activities and subsequent exoskeleton concept optimization. Six motion sequences were captured in the laboratory for three subjects and analyzed in multibody simulations with respect to muscle activities (MAs) and joint forces (JFs). The most strenuous sequence was selected and utilized in further simulations of a human model connected to 32 exoskeleton concept variants. Six simulated concepts were compared concerning occurring JFs and MAs as well as interaction loads in the exoskeleton arm interfaces. Symmetric uplifting of a 21 kg box from hip to shoulder height was identified as the most strenuous motion sequence with highly loaded arms, shoulders, and back. Six concept variants reduced mean JFs (spine: >70%, glenohumeral joint: >69%) and MAs (back: >63%, shoulder: >59% in five concepts). Parasitic loads in the arm bracing varied strongly among variants. An exoskeleton design was identified that effectively supports heavy lifting, combining high musculoskeletal relief and low parasitic loads. The applied workflow can help developers in the optimization of exoskeletons.
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    Multi-method model for the investigation of disassembly scenarios for electric vehicle batteries
    (2023) Baazouzi, Sabri; Grimm, Julian; Birke, Kai Peter
    Disassembly is a pivotal technology to enable the circularity of electric vehicle batteries through the application of circular economy strategies to extend the life cycle of battery components through solutions such as remanufacturng, repurposing, and efficient recycling, ultimately reintegrating gained materials into the production of new battery systems. This paper aims to develop a multi-method self-configuring simulation model to investigate disassembly scenarios, taking into account battery design as well as the configuration and layout of the disassembly station. We demonstrate the developed model in a case study using a Mercedes-Benz battery and the automated disassembly station of the DeMoBat project at Fraunhofer IPA. Furthermore, we introduce two disassembly scenarios: component-oriented and accessibility-oriented disassembly. These scenarios are compared using the simulation model to determine several indicators, including the frequency of tool change, the number and distribution of robot routes, tool utilization, and disassembly time.
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    Analytic free-energy expression for the 2D-Ising model and perspectives for battery modeling
    (2023) Markthaler, Daniel; Birke, Kai Peter
    Although originally developed to describe the magnetic behavior of matter, the Ising model represents one of the most widely used physical models, with applications in almost all scientific areas. Even after 100 years, the model still poses challenges and is the subject of active research. In this work, we address the question of whether it is possible to describe the free energy A of a finite-size 2D-Ising model of arbitrary size, based on a couple of analytically solvable 1D-Ising chains. The presented novel approach is based on rigorous statistical-thermodynamic principles and involves modeling the free energy contribution of an added inter-chain bond DAbond(b, N) as function of inverse temperature b and lattice size N. The identified simple analytic expression for DAbond is fitted to exact results of a series of finite-size quadratic N N-systems and enables straightforward and instantaneous calculation of thermodynamic quantities of interest, such as free energy and heat capacity for systems of an arbitrary size. This approach is not only interesting from a fundamental perspective with respect to the possible transfer to a 3D-Ising model, but also from an application-driven viewpoint in the context of (Li-ion) batteries where it could be applied to describe intercalation mechanisms.
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    Anti-adhesive surfaces inspired by bee mandible surfaces
    (2023) Saccardi, Leonie; Schiebl, Jonas; Balluff, Franz; Christ, Ulrich; Gorb, Stanislav N.; Kovalev, Alexander; Schwarz, Oliver
    Propolis, a naturally sticky substance used by bees to secure their hives and protect the colony from pathogens, presents a fascinating challenge. Despite its adhesive nature, honeybees adeptly handle propolis with their mandibles. Previous research has shown a combination of an anti-adhesive fluid layer and scale-like microstructures on the inner surface of bee mandibles. Our aim was to deepen our understanding of how surface energy and microstructure influence the reduction in adhesion for challenging substances like propolis. To achieve this, we devised surfaces inspired by the intricate microstructure of bee mandibles, employing diverse techniques including roughening steel surfaces, creating lacquer structures using Bénard cells, and moulding resin surfaces with hexagonal patterns. These approaches generated patterns that mimicked the bee mandible structure to varying degrees. Subsequently, we assessed the adhesion of propolis on these bioinspired structured substrates. Our findings revealed that on rough steel and resin surfaces structured with hexagonal dimples, propolis adhesion was significantly reduced by over 40% compared to unstructured control surfaces. However, in the case of the lacquer surface patterned with Bénard cells, we did not observe a significant reduction in adhesion.
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    Influence of temperature and pressure on the wetting progress in 21700 lithium‐ion battery cells : experiment, model, and lattice Boltzmann simulation
    (2024) Wanner, Johannes; Burgard, Matthias; Othman, Nabih; Singh, Soumya; Birke, Kai Peter
    The electrolyte filling and subsequent wetting of the active material is a time‐critical process in the manufacturing of lithium‐ion batteries. Due to the metallic cell housing, the process phenomena are insufficiently accessible, preventing the replication of the wetting processes by mathematical or simulative methods and hindering efforts to accelerate the wetting process. Therefore, this publication employs a glass cell housing for electrolyte filling of a 21700 cylindrical cell to investigate the wetting at different temperatures and process pressures. In parallel, a mathematical replication of the wetting, as well as a lattice Boltzmann pore‐scale simulation, is used to evaluate the influence of these varying process boundary conditions. The results show a strong temperature dependence on electrolyte wetting and the positive effect of pressure changes in the wetting process. These findings are particularly relevant to the process design of large‐scale cylindrical cell manufacturing.
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    CHEMampere : technologies for sustainable chemical production with renewable electricity and CO2, N2, O2, and H2O
    (2022) Klemm, Elias; Lobo, Carlos M. S.; Löwe, Armin; Schallhart, Verena; Renninger, Stephan; Waltersmann, Lara; Costa, Rémi; Schulz, Andreas; Dietrich, Ralph‐Uwe; Möltner, Lukas; Meynen, Vera; Sauer, Alexander; Friedrich, K. Andreas
    The chemical industry must become carbon neutral by 2050, meaning that process‐, energy‐, and product‐related CO2 emissions from fossil sources are completely suppressed. This goal can only be reached by using renewable energy, secondary raw materials, or CO2 as a carbon source. The latter can be done indirectly through the bioeconomy or directly by utilizing CO2 from air or biogenic sources (integrated biorefinery). Until 2030, CO2 waste from fossil‐based processes can be utilized to curb fossil CO2 emissions and reach the turning point of global fossil CO2 emissions. A technology mix consisting of recycling technologies, white biotechnology, and carbon capture and utilization (CCU) technologies is needed to achieve the goal of carbon neutrality. In this context, CHEMampere contributes to the goal of carbon neutrality with electricity‐based CCU technologies producing green chemicals from CO2, N2, O2, and H2O in a decentralized manner. This is an alternative to the e‐Refinery concept, which needs huge capacities of water electrolysis for a centralized CO2 conversion with green hydrogen, whose demand is expected to rise dramatically due to the decarbonization of the energy sector, which would cause a conflict of use between chemistry and energy. Here, CHEMampere's core reactor technologies, that is, electrolyzers, plasma reactors, and ohmic resistance heating of catalysts, are described, and their technical maturity is evaluated for the CHEMampere platform chemicals NH3, NOx, O3, H2O2, H2, CO, and CxHyOz products such as formic acid or methanol. Downstream processing of these chemicals is also addressed by CHEMampere, but it is not discussed here.