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The finite cell method for the prediction of machining distortion caused by initial residual stresses in milling

Procedia CIRP 2021年 102卷 144-149页

作者： M. Landwehr S. Schmid V. Holla P. Ganser T. Bergs M. Ruess K.-U. Schröder Fraunhofer Institute for Production Technology IPT Steinbachstrasse 17 52074 Aachen Germany Institute of Structural Mechanics and Lightweight Design (SLA) of RWTH Aachen University Wüllnerstrasse 7 52062 Aachen Germany Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Faculty of Mechanical and Process Engineering Düsseldorf University of Applied Sciences Münsterstrasse 156 40476 Düsseldorf Germany

Machining distortion caused by residual stresses is one of the major challenges in the production of thin-walled monolithic parts, which are widely used in the aerospace industry. This distortion often results in large deviations in form and position outside the tolerance requirements of the part. Time-consuming and cost-intensive running-in processes or manual reworking are therefore necessary to meet the tolerances of the parts. Current research mainly uses the finite element method (FEM) to predict machining distortion caused by residual stresses. However, the disadvantage of the FEM is the high manual effort required to generate a computational mesh of the in-process workpiece (IPW). Moreover, the FEM demands a very fine mesh, which has to be frequently updated by remeshing, to be in good agreement with the IPW. This leads to high computation times overall. In this paper, a novel machining distortion prediction method based on the Finite Cell Method (FCM) is presented. A major advantage of FCM compared to the established FEM in the context of milling simulation is the decoupling of the computational mesh and the IPW geometry, which allows for analysis updates of the modified IPW due to material removal, without the need for expensive re-meshing. Thus, the time complexity of the simulation can be reduced significantly. The milling process of a thin-walled part made of Ti-6Al-4V was considered to demonstrate the overall simulation approach.

关键词： Finite cell method Finite element method Machining distortion prediction Residual stress Milling Ti-6Al-4V

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Methodology for the design of recursively axially formed rotor shafts made of two or more combined segments

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Procedia Manufacturing 2019年 27卷 13-20页

作者： R. Kurth R. Tehel T. Päßler H. Wagner D. Beihofer Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Straße 88 09126 Chemnitz Germany Felss Systems GmbH Dieselstraße 2 75203 Königsbach-Stein Germany

Electric drives are used in all industrial fields in a growing number. Whereas the rotor shafts used in the area of machinery and plant engineering are designed as solids, the shafts mainly used in the field of automotive industry are hollow shafts focusing on the lightweight potential and the improvement of motor characteristics. This paper describes a shaft design consisting of two or more segments manufactured by a new combination of certain cold forming processes before joining. This design enables higher flexibility of variants as well as optimization of production efficiency and logistic chains. Thus, the joint zone design is a special serration with a helix angle in order to reach a high robustness of the shaft. A detailed FEM simulation of the elastoplastic behavior of the joint zone and the mechanical characteristics of the complete shaft leads to an evaluation of possible applications of this joint geometry and the corresponding manufacturing process. Based on experimental investigations, the simulations have been validated successfully. An empirical model designed by regression analysis of further simulation results is used to propose a design methodology for the identification of design parameters of the assembled shaft and the joint zone as well. These parameters can be used for planning the forming processes and the blank geometry.

关键词： forming rotor shaft finite element method (FEM) axial forming rotary swaging joining serration

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Adapted scan strategy and slicing tool for improvement of strut precision in lattice structures

Adapted scan strategy and slicing tool for improvement of st...

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2018 ASPE and euspen Summer Topical Meeting on Advancing Precision in Additive Manufacturing

作者： Korn, Hannes Koch, Peter Kordaß, Richard Holtzhausen, Stefan Schöne, Christine Müller, Bernhard Stelzer, Ralph Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz / Dresden Saxony Germany Institute of Machine Elements and Machine Design Technische Universität Dresden Dresden Saxony Germany

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Highly iterative concept development for requirement-compliant air taxis

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IOP Conference Series: Materials Science and Engineering 2022年第1期1226卷

作者： G. Schuh M. Spangenberg T. Meyer-Hollatz Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Campus-Boulevard 30 52074 Aachen Germany Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 52047 Aachen Germany

The increasing demand for individual mobility worldwide is leading to the development of new forms of mobility. Individual air mobility (e.g., air taxis) could be one innovative approach to meet this increasing demand. To successfully realise such innovative approaches, interested companies must know the technical, economic, and ecological requirements of all relevant stakeholders and integrate them in their air taxi developments. Based on these diverse requirements, a resilient air taxi concept must first be created that describes the essential characteristics of future air taxis and enables a well-founded assessment. However, in practice, it is often difficult for companies to outline such a concept and then develop it consistently and highly iteratively. To face this challenge, a process has been set up which creates a deep link between the requirements and concept development phase to assure the development of requirement-compliant air taxis in an agile manner. The process is divided into two parts. The first part connects the market analysis, requirements definition and concept creation, thus linking the requirements and concept development phase. It is based on a double diamond model consisting of two phases. In contrast, the second part is focusing on the pre-development until the end of the concept development phase by adapting the SCRUM methodology to derive a sound air taxi concept. Both parts are executed in a highly iterative manner to reflect the significant amount of uncertainty at this early process stages.

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Cover Picture: Insights Into Scalable Technologies and Process Chains for Sulfide-Based Solid-State Battery Production (Batteries & Supercaps 7/2024)

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Batteries & Supercaps 2024年第7期7卷

作者： Célestine Singer Lovis Wach Elena Jaimez Farnham Rüdiger Daub Technical University of Munich TUM School of Engineering and Design Institute for Machine Tools and Industrial Management Boltzmannstr. 15 85748 Garching (Munich) Germany TUMint.Energy Research GmbH Lichtenbergstr. 4 85748 Garching (Munich) Germany Fraunhofer Institute für Casting Composite and Processing Technology (IGCV) Am Technologiezentrum 2 86159 Augsburg Germany

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“Evaluation of a method to measure the friction coefficient between vital mandibular bone and biomedical materials”

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Biotribology 2021年 28卷

作者： Ben Achour, Anas Petto, Carola Meißner, Heike Mostofa, Anita Teicher, Uwe Ihlenfeldt, Steffen Lauer, Günter Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden 01187 Germany Department of Oral and Maxillofacial Surgery University Hospital Carl Gustav Carus Dresden Technische Universität Dresden Fetscherstraße 74 Dresden 01307 Germany Department of Prosthetic Dentistry University Hospital Carl Gustav Carus Dresden Technische Universität Dresden Fetscherstraße 74 Dresden 01307 Germany

Purpose: The aim of this study is to evaluate a developed experimental set-up to measure the coefficient of friction between fresh mandibular bone and biomaterials used in oral and maxillofacial surgery including a standardized routine for specimen preparation. Material and methods: For this purpose, we developed a specialized routine for harvesting and preparation of cortical bone specimen from cadaveric porcine mandibles and modified a ball-plate tribometer. These harvested bone specimen were kept moist all the time. A total of 24 bone cylinders with 8 repetitions per material were examined for their coefficient of friction against stainless steel (1.4404), a titanium alloy (Ti6Al4V) and a cobalt‑chromium‑molybdenum alloy (Biosil F®) and subsequently analyzed by laser-scanning and scanning electron microscopy. Results: The lowest coefficients of friction between vital cortical bone and the investigated implant materials were found for Biosil F®, while the highest coefficients of friction were found for the titanium alloy Ti6Al4V. Significant differences for the initial coefficient of friction with p < 0.05 have been proven. Stick-slip effects occurred during the measurement and a layer of debris formed on the metallic samples. EDX analysis of the abrasion marks revealed that this layer consisted of elements contained in hydroxyapatites and carbon. Conclusion: The experimental set-up is suitable to perform reproducible comparative measurements of the coefficient of friction of different material combinations. A significant advantage of the methodology is the flexibility and scalability of harvesting and preparation of the bone specimen, which allows the simulation of realistic situations while measuring the coefficient of friction. © 2021 Elsevier Ltd

关键词： Biotribology Bone Experimental Friction coefficient Implant materials Tribology

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Process-oriented Flow Curve Determination at Mechanical Joining

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Procedia Manufacturing 2020年 47卷 368-374页

作者： Mathias Jäckel Sam Coppieters Nelis Vandermeiren Christian Kraus Welf-Guntram Drossel Noa Miyake Toshihiko Kuwabara Klaus Unruh Heinrich Traphöner A. Erman Tekkaya Tudor Balan Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden 01187 Germany KU Leuven Technology Campus Ghent Department of Materials Engineering Gebroeders De Smetstraat 1 Ghent 9000 Belgium Belgium Welding Institute Technologiepark 48 Ghent 9052 Belgium Institute of Engineering Tokyo University of Agriculture and Technology 3 Chome-8-1 Harumicho Tokyo 183-8538 Japan Faurecia Autositze GmbH Nordsehler Straße 38 Stadthagen 31655 Germany Institute of Forming Technology and Lightweight Components TU Dortmund Baroper Straße 303 Dortmund 44227 Germany Arts et Metiers Institute of Technology Université de Lorraine LCFC HESAM Université F-57070 Metz France

The accuracy of numerical simulation models for forming processes depends highly on the method for the flow curve determination. Numerous experimental tests exist to identify the flow curves of sheet metals, each with certain characteristics regarding stress states and achievable strains. In this paper stress state analysis are presented for the mechanical joining techniques clinching as well as self-pierce riveting with semi-tubular rivet (SPR). Based on these findings flow curves for DC04 material are determined by selected experimental materials tests in order to compare the influence of the flow curve determination method on the accuracy of the process simulation models.

关键词： Mechanical Joining Material Chracterization Numerical Simulation

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Model for the Logic Determination of Innovation Ideas for Technical Systems

Model for the Logic Determination of Innovation Ideas for Te...

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International Scientific Conference on Information technology and Management Science of Riga Technical University (ITMS)

作者： Gunther Schuh Thomas Schwarberg Jonas Muhlbauer Nihan Yıldırım Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen Univsersity Aachen Germany Fraunhofer Institute for Production Technology IPT Aachen Germany Deparment of Management Engineering Istanbul Technical University Istanbul Turkey

ISBN: (数字)9781728191058

ISBN: (纸本)9781728191065

No company can survive in today's market environment without being innovative. Every innovation starts with an innovation idea (referred to as “idea” within this paper). Creativity techniques like Design Thinking enable the generation of a variety of ideas. However, selecting the right ideas for development and market launch imposes a challenge to companies which is yet unsolved. Recent studies show that only one out of 3,000 initially selected ideas leads to a successful product innovation. This poor success rate is due to an exclusive focus of today's evaluation processes on the idea's potential economic return. The functional and technological realization of this potential, however, is mostly neglected. Therefore, this paper aims at developing a model for assessing the realizability of innovation ideas for technical systems. For this purpose, the authors suggest applying the concept of logic determination to the evaluation of ideas.

关键词： Technological innovation Coherence Companies Harmonic analysis Economics Creativity Context modeling

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A modular LCA/LCC-modelling concept for evaluating material and process innovations in carbon fibre manufacturing

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Procedia CIRP 2021年 98卷 529-534页

作者： Thomas Groetsch Claudia Creighton Russell Varley Alexander Kaluza Antal Dér Felipe Cerdas Christoph Herrmann Carbon Nexus at the Institute for Frontier Materials Deakin University Geelong Victoria 3216 Australia Chair of Sustainable Manufacturing and Life Cycle Engineering Institute of Machine Tools and Production Technology (IWF) Technische Universität Braunschweig Langer Kamp 19b 38106 Braunschweig Germany Open Hybrid LabFactory e.V. Hermann-Münch-Straße 2 38440 Wolfsburg Germany Fraunhofer Institute for Surface Engineering and Thin Films (IST) Bienroder Weg 54e 38108 Braunschweig Germany

Widespread use of carbon fibre across various industry sectors remains limited due to the high costs of the raw materials and energy demands during production. Furthermore, the environmental impacts associated with its manufacturing process, may significantly reduce the potential benefits of weight reduction or material savings in the end products. Despite the excellent mechanical and chemical properties, which would make the material a viable substitute in a wide range of applications, further production and cost improvements are necessary to raise interest and demand. The scarcity of available carbon fibre production related data and the confidentiality of the few commercial carbon fibre suppliers hinders further research efforts towards these improvements. This paper proposes a dynamic, modular Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) concept tailored for carbon fibre production and is based on a pilot production set-up (120t/year). The model is intended to accelerate the assessment of carbon fibre production and serves as a tool for the exploration of various scenarios, including alternative precursor material, different carbon fibre grades or varying production parameters. In this paper the model is specified, embedded in the environment it is intended to be used and applied to a production setup based on data collected using the pilot scale carbonisation line at Carbon Nexus, a unique, open-access carbon fibre/composite research facility in Victoria, Australia.

关键词： Life cycle assessment modular LCA simplified LCA carbon fibre production

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Optical Coherence Tomography Combined with Convolutional Neural Networks Can Differentiate between Intrahepatic Cholangiocarcinoma and Liver Parenchyma ex vivo

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HPB 2023年 25卷 S275-S276页

作者： Wolff, L.I. Hachgenei, E. Jöchle, K. Frye, M. König, N. Schmitt, R.H. Ulmer, T.F. Neumann, U.P. Jonigk, D.D. Lang, S.A. Amygdalos, I. University Hospital RWTH Aachen Department of General Visceral and Transplantation Surgery Aachen Germany Fraunhofer Institute for Production Technology IPT Department of Production Metrology Aachen Germany University RWTH Aachen Laboratory for Machine Tools and Production Engineering (WZL) Aachen Germany University Hospital RWTH Aachen Institute for Histopathology Aachen Germany

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