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Consistent Simulation Strategy for Heat Sources and Fluxes in Milling

Procedia CIRP 2017年 62卷 239-244页

作者： Matthias Putz Christian Oppermann Ulrich Semmler Michael Bräunig Umut Karagüzel Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Chemnitz University of Technology 09010 Chemnitz Germany Mechanical Engineering Department Istanbul Technical University 34437 Istanbul Turkey

The paper presents a consistent numerical simulation method for calculation of heat sources and heat fluxes in milling processes. First of all, by means of finite element simulation of the interrupted chip formation process the cutting heat source is calculated. Next, the non-steady-state heat fluxes into the workpiece, the chips and the tool are computed numerically. The computed fluxes serve as boundary conditions for thermo-mechanical FE workpiece and tool models. The numerical models are fitted and verified by experiments of S235 steel. The simulations show a good match with the force and temperature measurements of the cutting processes.

关键词： Milling Finite element method Simulation Experimentation

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Comparative Integrated Manufacturing Efficiency in Production Engineering

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Procedia CIRP 2017年 63卷 527-532页

作者： A.P. Kuznetsov H.-J. Koriath A.V. Kalyashina Moscow State University of Technology “STANKIN” 127055 Moscow Russia Fraunhofer Institute for Machine Tools and Forming Technology IWU 09126 Chemnitz Germany Kazan National Research Technical University Kazan Russia

At present a plurality of manufacturing methods, different manufacturing processes and manufacturing equipment are known in order to produce and customize work pieces and products. A new systematic approaches for the analysis and evaluation of manufacturing methods bases on the energy-information model as a conceptual approach to the comparative integrated manufacturing efficiency in production engineering. The integrated manufacturing efficiency is equal to the product of the efficiencies of matter, energy and information. The Comparative Integral Manufacturing Efficiency is the product of Quality rate, Effectiveness, Availability, devided by the product of (used Energy, used material, Emission ratio). A case study compares additive and removal process efficiencies for the production of a hollow cylinder. Proposed method for comparative integrated manufacturing efficiency will offer resource-efficient strategies for the creation and optimization of processes and technology applications.

关键词： manufacturing efficiency technological process

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Multiscale Multiphysics Simulation of a Pulsed Electrochemical Machining Process with Oscillating Cathode for Microstructuring of Impact Extrusion Punches

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Procedia CIRP 2017年 58卷 257-262页

作者： Ingo Schaarschmidt Mike Zinecker Matthias Hackert-Oschätzchen Gunnar Meichsner Andreas Schubert Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology D-09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 D-09126 Chemnitz Germany

The pulsed electrochemical machining (PECM) with oscillating cathode is a manufacturing technology which is used for shaping and surface structuring of different workpieces, e.g. impact extrusion punches. The principle behind the ECM-process is the controlled anodic dissolution of the workpiece material without any thermal or mechanical impact and independent from workpiece material hardness. In this study, a new multi-scale approach for the modelling of PECM with oscillating cathode was created integrating the short and long time scale physical phenomena. In the short time scale simulation step (t < 0.02 s) the physical processes (current density distribution, motion of cathode, heat and hydrogen generation) during one single oscillation were analyzed. An averaged dissolution speed at the anode boundary over the small time range was calculated. The averaged values were imported as initial and boundary conditions into the long times scale simulation step (t > 10 s). Within this simulation step, the anodic dissolution was simulated by deforming the geometry. This approach allows simulations for long overall time ranges (t > 1000 s) while considering the short times scale processes in combination with a relatively small computational effort. This multiscale and multiphysics model helps to analyze the differences between front and lateral working gap and supports the process design for the pulsed electrochemical machining with oscillating cathode.

关键词： Electro chemical machining (ECM) Material removal Multiscale-multiphysics-modelling

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Characterization of an Electrochemical Machining Process for Precise Internal Geometries by Multiphysics Simulation

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Procedia CIRP 2017年 58卷 175-180页

作者： Matthias Hackert-Oschätzchen Raphael Paul Michael Kowalick Danny Kuhn Gunnar Meichsner Mike Zinecker Andreas Schubert Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology D-09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 D-09126 Chemnitz Germany

In several fields of mechanical engineering internal precision geometries are applied. For this, application requirements like high shape accuracy, sufficient stability, high wear resistance or an increase of life time have to be fulfilled. However, there is also a demand on quick and precise manufacturing processes that are flexible in machining various internal geometries. Electrochemical machining (ECM) is a process which meets these requirements. This process allows surface structuring and shaping of metal components with high shape accuracy independently of the materials strength and hardness [1] . This study presents investigations on a developed process design for manufacturing internal precision geometries by pulsed electrochemical machining (PECM) with help of multiphysics simulations. The peculiarity of this process is the shaping of the workpiece by the lateral working gap. Multiphysics simulations were carried out to understand the respective interactions between several physical phenomena. Especially, fluid dynamical effects are described in detail within the developed model. Furthermore, Joule heating and cathodic hydrogen formation are included. The fluid flow ensures the removal of heat and hydrogen and a continual supply with fresh electrolyte, respectively. The electrical conductivity of the electrolyte is modeled as a function of hydrogen volume concentration and temperature. Hence, both effects, Joule heating and hydrogen formation, influence the current density distribution which in turn determines the material removal.

关键词： Electrochemical machining (ECM) Finite element method (FEM) Multiphysics Simulation

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Testing of magnetic pulse welded joints – Destructive and non-destructive methods

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AIP Conference Proceedings 2019年第1期2113卷

作者： Verena Psyk Christian Hofer Koen Faes Christian Scheffler Edgar Scherleitner 1Fraunhofer Institute for Machine Tools and Forming Technology Reichenhainer Strasse 88 09126 Chemnitz Germany 2Research Center for Non Destructive Testing GmbH (RECENDT) Altenberger Straße 69 4040 Linz Austria 3Belgian Welding Institute BWI Technologiepark 935 9052 Zwijnaarde Belgium

Electromagnetic pulse welding is an innovative technology suitable for joining various similar and dissimilar tube and sheet metal parts including dissimilar material combinations, which are difficult to join by conventional, i.e. thermal welding methods. In case of proper choice of process parameters, a high joint quality can be achieved. In literature this is often demonstrated by failure in the base material during destructive testing. However, no standard testing procedures for magnetic pulse welded joints have been agreed on and thus industrial implementation is severely complicated. Specifically, investigations regarding non-destructive testing are rarely available. The paper evaluates different testing and characterization methods. Specifically, metallographic analysis and lap shear tests are taken into consideration. Finally, Laser UltraSound (LUS) is presented as a new alternative for characterizing magnetic pulse welded joints. The technique is based on measuring laser ultrasound waves which are either transmitted through or reflected by the weld seam. A comparison of the results to those of the more established destructive testing methods shows, that LUS measurements absolutely allow qualitative and quantitative conclusions regarding weld quality. Due to high automation potential, the method is a promising alternative for quality control in industrial manufacturing.

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Influence of Global Forced-air Warming on the Bulge Formation in Shallow Sloped SPIF Parts

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Procedia Engineering 2017年 183卷 149-154页

作者： Amirahmad Mohammadi Hans Vanhove Dieter Weise Albert Van Bael Dirk Landgrebe Joost R. Duflou KU Leuven Department of Mechanical Engineering Heverlee 3001 Belgium Fraunhofer-Institut for Machine Tools and Forming Technology IWU Department Sheet Metal Processing Chemnitz 09126 Germany KU Leuven Department of Materials Engineering Heverlee 3001 Belgium

Shallow sloped single point incrementally formed (SPIF) parts typically show undesirable geometric deviations from the designed shape due to accumulated unwanted bulging. In this study, the effect of global heating by forced-air warming on the geometric accuracy of low-angled parts with a conical geometry is investigated. A finite element (FE) model was developed to simulate the SPIF process at elevated temperatures. The simulation results show that the sheet metal is subjected to significantly higher levels of stress in cold forming condition with respect to parts formed at elevated temperatures. Due to the increase in strength caused by strain hardening, a larger area of the sheet (both in the wall and bulge regions) is affected by the tool during forming at room temperature. Softening of the material by heat-assisted forming reduces the strain hardening and extended straining of the part which results in a reduction of the bulge height and of the under-forming of the cone base.

关键词： Single Point Incremental forming Global heating FE modeling

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Sensing and Actuating Functions by Shape Memory Alloy Wires Integrated into Fiber Reinforced Plastics

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Procedia CIRP 2017年 66卷 249-253页

作者： Björn Senf Thomas Mäder Iñaki Navarro y de Sosa André Bucht Marcus Knobloch David Löpitz Welf-Guntram Drossel Fraunhofer Institute for Machine Tools and Forming Technology IWU Noethnitzer Strasse 44 01187 Dresden Germany Technische Universität Chemnitz Reichenhainer Straße 70 09126 Chemnitz Germany

Lightweight design based on fiber reinforced plastics (FRP) has potential for improvement by integration of sensors and actuators made of smart material filaments. Regarding FRP with integrated actuating shape memory alloy (SMA) wires, this paper presents important characteristics of such an adaptive composite and its components for design purposes. Beyond that, the first successful pultrusion processing of sensing SMA wires is proposed to address lightweight design mass production for safety-related applications. Measurements of this smart composite structure with strain sensor functionality proved high sensitivity compared to conventional sensors.

关键词： shape memory alloy wires SMA fiber refinorced plastics FRP lightweight design smart composite structure pultrusion

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Resource-efficient development of thermally highly resistant engine components of hybrid metal composites – experiments and numerical analysis

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Procedia Engineering 2017年 207卷 884-889页

作者： Dirk Landgrebe Lutz Krüger Nadine Schubert Eric Jentsch Tim Lehnert Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 09126 Chemnitz Germany Institute for Materials Engineering TU Bergakademie Freiberg Gustav-Zeuner-Straße 5 09599 Freiberg Germany

Requirements for protection of environment and climate, increasing energy cost and security demands form the basis for research activities in the maritime sector. Within the scope of the joint project »INKOV – development of innovative piston and valve solutions for composites in ship engines« metallic composites are developed and investigated. Their application in large engines powered by heavy fuel oil shall reduce nitrogen oxide emissions. The investigations of the publicly funded research project intend to generate high-strength components made of a hybrid composite material while simultaneously increasing resource efficiency. The focus of the research and development activities lies on components for large engines which are subject to extremely high dynamic, thermal and corrosive loads. Using conventional heat-resistant and wear-resistant steels, the wear related to the conditions of the application site can hardly be controlled. High-performance alternatives are necessary. The goal of the approach is to specifically apply a nickel-base alloy to a locally limited area by using a selected thermal joining process. Thus, a layer composite is to be produced, which corresponds to the solid material of a nickel-base alloy regarding its properties of thermal resistance and corrosion resistance. Currently, criteria for excluding the integration of these materials include high prices as well as their partly limited availability despite of their reported suitability for high-temperature applications. Using hybrid materials should open up their considerable potential in terms of increasing strength and high-temperature resistance while simultaneously reducing wear-related downtimes to a minimum. An aim of the project is to implement forming processes of hybrid composites by means of simulation as a basis for optimizations in terms of joining materials, joining processes or geometrical dimensions. Furthermore, the basic behavior of hybrid materials and their interface shal

关键词： hybrid composite material resource efficiency FEM bulk metal forming

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Pelvic orthosis effects on the kinematics of the posterior pelvis

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Journal of Bodywork & Movement Therapies 2018年第4期22卷 847-847页

作者： Hammer, Niels Klima, Stefan Scholze, Mario Seidel, Thomas Werner, Michael Grunert, Ronny University of New Zealand New Zealand University of Otago New Zealand FAU Erlangen Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Dresden Germany

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Characterization of material parameters for high speed forming and cutting via experiment and inverse simulation

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AIP Conference Proceedings 2018年第1期1960卷

作者： Christian Scheffler Verena Psyk Maik Linnemann Marc Tulke Alexander Brosius Dirk Landgrebe 1)Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 D-09112 Chemnitz 2)Technische Universität Dresden Chair of Forming Processes FF D-01062 Dresden

High speed velocity effects in production technology provide a broad range of technological and economic advantages [1, 2]. However, exploiting them necessitates the knowledge of strain rate dependent material behavior in process modelling. In general, high speed material data characterization features several difficulties and requires sophisticated approaches in order to provide reliable material data. This paper proposes two innovative concepts with electromagnetic and pneumatic drive and an approach for material characterization in terms of strain rate dependent flow curves and parameters of failure or damage models. The test setups have been designed for investigations of strain rates up to 105 s-1. In principle, knowledge about the temporary courses and local distributions of stress and strain in the specimen is essential for identifying material characteristics, but short process times, fast changes of the measurement values, small specimen size and frequently limited accessibility of the specimen during the test hinder directly measuring these parameters at high-velocity testing. Therefore, auxiliary test parameters, which are easier to measure, are recorded and used as input data for an inverse numerical simulation that provides the desired material characteristics, e.g. the Johnson-Cook parameters, as a result. These parameters are a force equivalent strain signal on a measurement body and the displacement of the upper specimen edge.

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