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Proceedings of the Fortieth Conference on Uncertainty in Artificial Intelligence

作者： Dorina Weichert Alexander Kister Sebastian Houben Patrick Link Gunar Ernis Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS Sankt Augustin Germany VP.1 eScience Federal Institute for Materials Research and Testing BAM Berlin Germany University of Applied Sciences Bonn-Rhein-Sieg Sankt Augustin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany and Institute of Mechatronic Engineering TUD Dresden University of Technology Dresden Germany

The practical use of Bayesian Optimization (BO) in engineering applications imposes special requirements: high sampling efficiency on the one hand and finding a robust solution on the other hand. We address the case of adversarial robustness, where all parameters are controllable during the optimization process, but a subset of them is uncontrollable or even adversely perturbed at the time of application. To this end, we develop an efficient information-based acquisition function that we call Robust Entropy Search (RES). We empirically demonstrate its benefits in experiments on synthetic and real-life data. The results show that RES reliably finds robust optima, outperforming state-of-the-art algorithms.

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Experimental investigations on the bonding of alkaline electrolytic cells

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Procedia CIRP 2024年 130卷 1758-1763页

作者： Rudolf Griemert Paul Bobka Martin Römer Klaus Dröder Institute of Machine Tools and Production Technology Technische Universität Braunschweig Langer Kamp 19b Braunschweig 38106 Germany Fraunhofer Institute for Surface Engineering and Thin Films IST Riedenkamp 2 Braunschweig 38108 Germany

Green hydrogen is becoming an increasingly relevant alternative to fossil fuels for various applications. Alkaline water electrolysis (AEL) is a promising technology to meet this growing demand. However, scaling up the production of AEL cells in a cost-efficient manner is challenging, as current cell designs are not optimized for automated assembly processes. This is a result of the conventionally required large number of individual parts such as screws, nuts, washers and isolation tubes for joining the half shells of one cell. To address this challenge, the present research investigates the feasibility of adapting the cell design by replacing the conventional screw-based joining processes with an adhesive-based design. As a first step, the required adhesive properties for use in AEL cell design are identified. Following this, four selected adhesives are experimentally analysed regarding their suitability. To accomplish this, adhesive samples are placed inside of an AEL cell and exposed to continuous cell operation for 10 hours. The adhesives are optically analysed and the Shore hardnesses and tensile shear strengths are compared before and after exposure. The results demonstrate the suitability of the investigated epoxy-based adhesives regarding the required chemical resistance and mechanical strength. To evaluate the feasibility of the selected adhesive, a 250 x 500 mm AEL cell demonstrator with this concept is operated in a test facility, proving the electrochemical feasibility and sufficient electrical insulation of this approach. However, the chemical resistance and especially the impermeability proved to be lacking, highlighting the necessity for further investigations into chemically resistant adhesives for the application in electrolyseur manufacturing. Overall, this research opens up the possibility for increasingly cost-effective and scalable AEL production processes, which is an influential factor for achieving a sustainable supply of green hydrogen.

关键词： Design for assembly Alkaline water electrolysis Adhesive Bonding

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Improving the Energy Efficiency of machine tools using a Thermal Storage Unit based on a Phase Change Material

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Procedia CIRP 2024年 125卷 308-313页

作者： Nico Bertaggia Daniel Reibert Phillip Knuth Daniel Zontar Christian Brecher Fraunhofer Institute of Production Technology (IPT) Steinbachstr. 17 52074 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) of the RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany

Today there are many ideas investigated to find ways for industries to become more environmentally friendly and sustainable. To reduce the energy consumption of machine tools and thus increase the efficiency of production, this paper discusses the idea of a heat accumulator based on a phase change material (PCM). In the context of biologisation in production technology, this work is based on the principle of heat storage in equi-warm organisms. Since machine tools deform under thermal influences and thus affect the machining process, they are often operated in idle mode before the work process to reach a thermally stable state and reduce thermally induced deformation during the production process. The machine is actively tempered using the cooling circuit to keep the temperature plateau constant. The idea of the PCM unit presented in this paper is to store this excess and otherwise dissipated energy. This can be used before the machines next process cycle to induce heat into the machine and reach the stable temperature plateau without operating the machine. The conditions under which the energy consumption can be reduced using this method and thus making the operation more sustainable are discussed and first simulations show that the goal is achievable.

关键词： thermal storage unit machine tools phase change materials biologisation energy efficency

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Signal conditioning of a novel ultrasonic transducer with integrated temperature and amplitude sensors

Signal conditioning of a novel ultrasonic transducer with in...

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IEEE Southeastcon

作者： Bsher Karbouj Jörg Krüger Institute of Machine Tools and Factory Management Technical University of Berlin Berlin Germany Fraunhofer Institute for Production Systems and Design Technology Berlin Germany

Vibration amplitude of ultrasonic transducer has an impact on the overall process quality, process speed and ultrasonic transducer lifetime in industrial applications. A new ultrasonic transducer design has been developed with integrated sensor disks that have different electrical and mechanical properties. The combination of sensor has been designed for amplitude measurements and is also able to measure the transducer temperature in the real time. This paper deals with the analog signal processing that combines the different "raw" signals from the sensor disks to extract the information such as amplitude and temperature. For this goal, a chain of different signal filters and adjustment elements was used. Reliable amplitude and temperature measurements during real-time operation were obtained by the applied signal processing. The obtained results were validated with an external temperature sensor and a laser vibrometer.

关键词： Temperature measurement Ultrasonic transducers Temperature sensors Vibrations Temperature Ultrasonic variables measurement Vibrometers

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Robust Entropy Search for Safe Efficient Bayesian Optimization

arXiv

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arXiv 2024年

作者： Weichert, Dorina Kister, Alexander Houben, Sebastian Link, Patrick Ernis, Gunar Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS Sankt Augustin Germany VP.1 eScience Federal Institute for Materials Research and Testing BAM Berlin Germany University of Applied Sciences Bonn-Rhein-Sieg Sankt Augustin Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Institute of Mechatronic Engineering TUD Dresden University of Technology Dresden Germany

关键词： Entropy

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DEM Simulation of Abrasive Brushing Processes on Additively Manufactured Workpieces

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Procedia CIRP 2025年 133卷 203-208页

作者： Anton Hoyer Eckart Uhlmann Institute for Machine Tools and Factory Management (IWF) Technische Universität Berlin Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

Brushing with bonded abrasives is a finishing process mainly used for deburring, edge rounding, and surface roughness reduction. The brushing tools consist of flexible polymer filaments embedded with abrasive grains, allowing them to adapt to complex workpiece shapes. However, interactions between filaments lead to complex motion, chipping, and wear behaviors, making it difficult to predict work results. The discrete element method (DEM) has been shown to be effective in simulating process forces, contact areas, and filament interactions on flat workpieces. Consequently, this article focuses on processing geometrically complex workpieces, particularly additively manufactured turbine fan blades (Ni-Cr-Co), using round brushes with bonded silicon carbide. First, a vectorized iterative method is introduced to generate artificial filament patterns, enhancing DEM simulation accuracy compared to state-of-the-art filament pattern models. Subsequently, dry brushing experiments are carried out on a fan blade feature demonstrator, aiming to achieve homogeneous roughness reduction. The qualitative analysis of the contact surface suggests that results from DEM simulations can reduce the need for costly technological investigations and prototypes.

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Advancing functional integration through multi-material additive manufacturing: Simulation and experimental validation of a burner nozzle

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Materials Today: Proceedings 2022年 70卷 296-303页

作者： Ringel, Bjoern Zaepfel, Martin Herlan, Florian Horn, Max Schmitt, Matthias Seidel, Christian Fraunhofer Institute for Casting Composite and Processing Technology IGCV Am Technologiezentrum 10 Augsburg 86159 Germany Technical University of Munich Institute for Machine Tools and Industrial Management Boltzmannstrasse 15 Garching 85748 Germany Department of Applied Sciences and Mechatronics Munich University of Applied Sciences Lothstr. 34 Munich 80335 Germany

A combination of simulation and experimental testing is introduced that opens the ability to evaluate the fluid-driven heat exchange of multi-material components. Multi-material laser powder bed fusion is used for processing a nickel-base (Ni) and a copper-base (Cu) alloy in one process fabricating a burner tip component. The multi-material component is compared to its mono-material counterpart made entirely from the Ni-base alloy. A computational fluid dynamics simulation is used to calculate the maximum component temperature differences between both components as-built and heat-treated leading to a theoretical thermal improvement of 36% in the burner tip. Differences between the experimentally achieved thermal improvement of 32% and the theoretical benchmark are discussed by metallographic part analysis. Using the example burner tip component, multi-material process-specific challenges and component design approaches are presented for future applications. © 2022

关键词： Copper alloys

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A CAD-based workflow and mechanical characterization for additive manufacturing of tailored lattice structures 29

A CAD-based workflow and mechanical characterization for add...

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29th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2018

作者： Koch, P. Korn, H. Kordass, R. Holtzhausen, S. Schoene, C. Mueller, B. Stelzer, R. Institute of Machine Elements and Machine Design TU Dresden Dresden Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany

Lattice structures are highly recommended for lightweight applications and cost reduction in additive manufacturing (AM). Currently, parts with lattice structures are still mainly used for illustrative purposes and rarely in industrial products. One important reason is that, due to their high dependency on macro- and micro-geometry, the mechanical properties of manufactured structures are difficult to predict. Thus, even and precise struts are needed. In this paper, a workflow for fabrication of lattice structures with strut-diameters from 150 µm to 400 µm on commercial laser beam melting (LBM) systems is presented. Based on a CAD-integrated user-interface for lattice design, a customized slicing algorithm determines database-aided suitable exposure parameters which ensure that the properties of the manufactured struts will just be as specified upon design. Subsequently, compression tests are performed in order to verify the established workflow. The developed tool enables designers to integrate AM-specific geometries into their components with little specific experience in AM. © Solid Freeform Fabrication 2018: Proceedings of the 29th Annual International Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference, SFF 2018. All Rights Reserved.

关键词： 3D printers

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Simulation of ultrasonic-assisted grinding for improved efficiency in hard-to-machine materials: A direct approach to analyze material removal mechanisms

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Procedia CIRP 2025年 133卷 209-214页

作者： Eckart Uhlmann Bernhard Gülzow Xinyu Zhang Technische Universität Berlin Institute for Machine Tools and Factory Management (IWF) Pascalstr. 8-9 10587 Berlin Germany Fraunhofer Institute for Production Systems and Design Technology IPK Pascalstr. 8-9 10587 Berlin Germany

The application of ultrasonic superposition is utilized in industrial manufacturing to enhance the chip formation mechanisms, particularly when machining hard-to-machine materials. The institute for machine tools and Factory Management (IWF) systematically investigates the interactions between tool and workpiece during ultrasonic-assisted grinding of high-performance ceramics. To gain an in-depth understanding of the microscopic engagement conditions, these conditions are analyzed by simulation. For this purpose, a Python simulation tool based on a geometrical-kinematic modeling approach was developed to analyze the ultrasonic-assisted circumferential longitudinal grinding process. It was demonstrated that ultrasonic assistance leads to smaller and more uniform chip thicknesses which reduce grinding forces and minimizes tool wear. Also, it promotes brittle chip formation mechanisms and improves the efficiency of the grinding process compared to conventional machining. For further investigation, the simulation model was adapted to the transverse face grinding process. In this context, not only the circumferential surface but also the face surface of the grinding tool is engaged with the workpiece. Additionally, the penetration of the workpiece is no longer tangential with the rotational movement but perpendicular to the tool movement. Analogous to the results of the analysis of the circumferential longitudinal grinding process, the influences of ultrasonic excitation on the engagement conditions, particularly the resulting chip thickness and surface topography for the adapted process kinematics were determined and are presented in this paper.

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Holistic differentiation factors for the strategic design of sustainable production networks

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Procedia CIRP 2023年 120卷 875-880页

作者： Günther Schuh Seth Schmitz Tino X. Schlosser Alexander Schollemann Florian Pfau Laboratory for Machine Tools and Production Engineering (WZL) at RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Aachen Germany

The increasing sustainability influences caused by internal and external stakeholders in the environment of manufacturing companies require a strategy adjustment taking into account the holistic sustainability dimensions. Besides meeting these adapted stakeholder requirements, the transformation also offers opportunities to increase long-term competitiveness by a targeted differentiation. Manufacturing in global production networks is considered to be a decisive lever for realizing competitive advantages. Within the strategic design of global production networks, the manufacturing strategy are specified based on differentiation factors, which have mainly addressed the economic dimension in the form of costs, quality or delivery performance. To meet the changing stakeholder demands and to leverage opportunities for competitiveness, a consideration of the holistic sustainability dimensions within the manufacturing strategy is required. Therefore, this paper aims to expand the differentiation factors of the manufacturing strategy to include the environmental and social sustainability dimensions. For this purpose, existing approaches were identified and analyzed from the perspective of production strategy and sustainability. Conclusively, constituting characteristics of differentiation factors are elaborated and examined for the derivation of the holistic differentiation factors of a sustainable production. Subsequently, existing generic strategy types for the reinforcement of competitive advantages are analyzed. These are further extended to generic strategy types of a sustainable production, taking into account the holistic differentiation factors.

关键词： Sustainability Strategy Manufacturing Strategy Differentiation Factors Global Production Networks

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