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Smart 3 – Smart Materials for Smart Applications

Procedia CIRP 2015年 36卷 211-216页

作者： W.-G. Drossel H. Kunze A. Bucht L. Weisheit K. Pagel Fraunhofer Institute for Machine Tools and Forming Technology

Smart Materials are designed materials that have one or more properties that can be significantly changed in a controlled fashion by an externally applied field value such as stress, temperature and electric or magnetic fields. This behavior is reversible and consequently enables these materials to fulfill actuation and sensing functions in one component. Compared to conventional systems such actuators are rather high integrated. They can be applied not just to be a discrete part of the system; they are the system itself combining sensing, actuation and mechanical functions. Certain actuating properties of Smart Materials are far beyond the ones of conventional actuating principles. These advantages possess to use them in special application areas such as lightweight construction, active vibration control or the development of highly dynamic systems for instance. The design of Smart Materials in highly integrated components is technically more advanced and requires interdisciplinary knowledge. In this paper we present three groups of Smart Materials: piezoceramics, shape memory alloys and dielectric elastomers and their specific characteristics. That covers their physical working principle, their mechanical behavior, the actuation and sensing properties. Especially the interdisciplinary design approach required for developing highly integrated components is exemplarily clarified on Shape Memory Alloys. To enable designers to use Smart Materials without having this special knowledge smart tools for smart design are presented.

关键词： Smart Materials Shape Memory Alloys Piezoceramics Dielectric Elastomeres Design Functional Integration

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Influence of process induced damages on joint strength when self-pierce riveting carbon fiber reinforced plastics with aluminum 18th

Influence of process induced damages on joint strength when ...

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18th International ESAFORM Conference on Material forming, ESAFORM 2015

作者： Landgrebe, Dirk Jäckel, Mathias Niegsch, Ronald Fraunhofer Institute for Machine Tools and Forming Technology IWU Nöthnitzer Straße 44 Dresden01189 Germany

ISBN: (纸本)9783038354710

The importance of environment friendly mobility strengthens the need of lightweight design in the automotive industry. New electric car models, like the BMW i3, already have car body with a high amount of carbon fiber reinforced plastics (CFRP) to allow, as a result of the low vehicle weight, appropriate ranges without reloading the battery. Methods for joining materials like CFRP play a key role to implement lightweight designs into car body production. Conventional joining methods like spot welding cannot be used for such material combinations. Due to the good automation and possible combination with adhesive, mechanical joining techniques such as selfpierce riveting (SPR) are very relevant for joining these lightweight materials. While generally selfpierce riveting of CFRP with aluminium is possible, different damages e.g. delaminations, fiber or matrix fractures in the CFRP can occur during the joining process and have to be considered. This paper shows an analysis of these process induced damages when self-pierce riveting CFRP compound with aluminum sheet metal and investigates their influence on the joint strength. In our research the conventional SPR process of CFRP-aluminium joints is compared to the application of a new die concept for SPR in which a separated die is used to reduce the process induced delaminations in the CFRP. Additionally, these joining results are contrasted to SPR joints with predrilled CFRP components. Through the pre-drilling the damages in the CFRP can nearly be avoided completely and so these joints can be used as a reference. The results of the three processes to produce CFRP-aluminum joints are compared by micrographs, computed tomography and strength tests. © (2015) Trans Tech Publications, Switzerland.

关键词： Carbon fiber reinforced plastics

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Inline Plasma Analysis as Tool for Process Monitoring in Laser Micro Machining for Multi-layer Materials

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Physics Procedia 2016年 83卷 1329-1338页

作者： Rouwen Kunze Guilherme Mallmann Robert Schmitt Fraunhofer Institute for Production Technology IPT Steinbachstr. 17 Aachen Germany Laboratory for Machine Tools and Production Engineering WZL RWTH Aachen University Aachen Germany

Laser micro machining is an innovative manufacturing technology with a wide range of processable materials and a high level of flexibility. Especially for processing multi-layer materials it is a tool for surface structuring and subsequent functionalization. The manufacturing of e.g. conductor paths for solar cells or batteries requires specific ablation depths on multi-layer materials in order to reveal conducting layers as functional conductor paths. To achieve an ablation of a specific, layer an in-line process monitoring can be used to warrant a robust manufacturing preventing damage on further surface layers. With regards on the need of material specific ablation parameters, this paper addresses the development of a measurement system based on laser induced breakdown spectroscopy (LIBS) as a tool for real-time process monitoring by in-line plasma analysis. The presented results show the specific plasma emission variation at layer interfaces, which can be used for real-time feedback process control with the goal of minimizing the ablation of further layers.

关键词： Laser induced breakdown spectroscopy plasma analysis laser emission spectroscopy in-line metrology real-time feedback

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Modification of the process dynamics in micro-EDM by means of an additional piezo-control system

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AIP Conference Proceedings 2017年第1期1896卷

作者： M. Herzig T. Berger H.-P. Schulze M. Hackert-Oschätzchen O. Kröning A. Schubert 1Leukhardt Schaltanlagen Systemzechnik GmbH 39120 Magdeburg Germany 2Professorship Micromanufacturing Technology Faculty of Mechanical Engineering Chemnitz University of Technology 09107 Chemnitz Germany 3Fraunhofer Institute for Machine Tools and Forming Technology 09126 Chemnitz Germany

For the application of spark erosion in micro- and precision manufacturing, it is particularly important that small structures with small spark gaps can be machined in the range of a few micrometers. Due to the application of an additional high- dynamic piezo positioning system, smaller feed steps can be implemented which ensure a higher process stability. This additional feed system can be adapted to existing feed systems, whereby the process variable to be influenced is the spark gap. The primary feed system does not have to be directly influenced. The article shows how the structures of parallel regulation circuits for such operating piezo positioning systems are constructed and how they can improve the productivity, the machining accuracy and the surface quality. A selected example shows how the structural design of the highly dynamic system can be designed for different process parameters of industrial basic systems.

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Process combination of hydroforming and injection moulding for the insitu manufacturing of metal and plastic composite structures 20th

Process combination of hydroforming and injection moulding f...

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20th Symposium on Composites, 2015

作者： Albert, André Drossel, Welf-Guntram Zorn, Wolfgang Nendel, Wolfgang Raithel, Dirk Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Technische Universität Chemnitz Chemnitz Germany

ISBN: (纸本)9783038355151

The use of lightweight structures is a major trend in the reduction of fuel consumption and CO2 emissions, especially in transport. Metal plastic hybrid structures are an efficient solution to use the best material at every point in the design space. In the state of the art production technologies, the metal parts are produced separately from the plastic parts. The injection moulding process is only used for forming the plastic parts and for joining. These process chains are very extensive. The article shows the development of new process combinations. The aim is a combination of metal forming and injection moulding in one die and one process. One part should be produced with every single stroke of the press. In the first step, deep drawing, injection molding and media based forming with the plastic melt were successfully merged in one tool and one process. It was possible to integrate the injection moulding process into a deep drawing machine. In the next step, it was possible to successfully combine hydroforming and injection molding. For this process combination the hydroforming process is integrated into an injection moulding press. Different surface structures of the metal tubes, such as sandblasting, knurling and laser structuring, were systematically tested regarding to their properties as an adhesion promoter. The target is to establish a purely mechanical connection between the hydroformed metal component and the injection moulded component from glass fibre reinforced plastic instead of the chemical bonding agents often used previously, such as Vestamelt®. © (2015) Trans Tech Publications, Switzerland.

关键词： Metals

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Pre-compensation of Warpage for Additive Manufacturing

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Journal of Mechanics Engineering and Automation 2016年第8期6卷 392-399页

作者： Christoph Schmutzler Fabian Bayerlein Stephan Janson Christian Seidel Michael F. Zaeh Institute for Machine Tools and Industrial Management Technical University Munich Augsburg 86153 Germany Fraunhofer Research Institution for Casting Composite and Processing Technology IGCV Augsburg 86153 Germany

Additive manufacturing technologies enable the production of parts by successively adding layers. In powder-based technologies, each powder layer is selectively solidified following the respective cross-section of the parts either by the application of high-energy radiation or by the selective deposition of binder. By repeating the steps of layer deposition and selective solidification, parts are fabricated. The layer-wise build-up and the ambient conditions lead to warpage of the parts due to the temporarily and locally uneven distribution of shrinkage throughout the part. This leads to deviations in shape and dimension. The development of these technologies fosters a change fi＇om prototyping to manufacturing applications, As a consequence, higher standards regarding the shape and dimensional accuracy are required. Therefore, new strategies to minimize the resulting deformations are necessary to reduce rejects and widen the range of applications of the described technologies. In this paper, an empirical, a knowledge-based and a simulative approach for warpage compensation are introduced. They are all based on the pre-deformation of the digital 3D part geometry inverse to the expected deformation during manufacturing. The aim of the research is the development of a comprehensive method that enables users to improve their part-quality by supporting the pre-deformation process. Contrary to existing work, this method should not be process-specific but cover a wide range of additive manufacturing techniques. Typical forms of deformation of the processes laser sintering, laser beam melting and 3D printing （powder-binder） are presented and compensation strategies are disenssed. Finally, an outlook on the ongoing research is given.

关键词： Additive manufacturing shrinkage warpage compensation pre-deformation simulation.

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Increasing Cost and Eco Efficiency for Selective Tape Placement and forming by Adaptive Process Design

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Procedia CIRP 2016年 57卷 769-774页

作者： C. Brecher R. Schmitt F. Lindner T. Peters M. Emonts M. Große Böckmann Department of Production Machines Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 Aachen 52074 Germany Chair of Machine Tools at Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Steinbachstraße 19 Aachen 52074 Germany Department of Production Quality and Metrology Fraunhofer Institute for Production Technology IPT Steinbachstraße 17 Aachen 52074 Germany Chair of Metrology and Quality Management at Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Steinbachstraße 19 Aachen 52074 Germany

The automated placement of continuous fiber-reinforced polymer prepregs (pre-impregnated) is a generative manufacturing technology for composites. Particularly laser-assisted tape placement of unidirectional continuous fiber-reinforced tapes provides potentials for highly flexible composite manufacturing. Whereas the single process of tape placement to generatively build up load carrying structures was already optimized in several research activities and projects, an integrated process chain approach promises further increases in cost and eco efficiency. An adaptive process design considering interdependencies between selective tape placement and a subsequent forming improves the entire process chain. Due to the knowledge of process interdependencies, the advantages of high speed placement on predetermined load carrying areas can be fully exploited. The system and process design for this adaptive manufacturing approach, the underlying assessment methodology as well as its application on a manufacturing process chain for structural composite parts are presented in this paper.

关键词： Selective high speed tape placement laser-assisted tape laying cost and eco efficiency generative composite manufacturing adaptive process design

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Mechanical joining of materials with limited ductility: Analysis of process-induced defects

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AIP Conference Proceedings 2017年第1期1896卷

作者： M. Jäckel S. Coppieters M. Hofmann N. Vandermeiren D. Landgrebe D. Debruyne T. Wallmersberger K. Faes 1Fraunhofer Institute for Machine Tools and Forming Technology IWU (Dresden Germany) 2KU Leuven Technology Campus Ghent Department of Materials Engineering (Ghent Belgium) 3TU Dresden Institute for Solid Mechanics (Dresden Germany) 4Belgium Welding Institute (Ghent Belgium)

The paper shows experimental and numerical analyses of the clinching process of 6xxx series aluminum sheets in T6 condition and the self-pierce riveting process of an aluminum die casting. In the experimental investigations the damage behavior of the materials when using different tool parameters is analyzed. The focus of the numerical investigations is the damage prediction by a comparison of different damage criteria. Moreover, strength-and fatigue tests were carried out to investigate the influence of the joining process-induced damages on the strength properties of the joints.

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Next generation hardware development: Framework for a tailorable development method

Next generation hardware development: Framework for a tailor...

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Portland International Conference on Management of Engineering and technology (PICMET)

作者： Günther Schuh Tim Wetterney Felix Lau Stephan Schröder Laboratory for Machine Tools and Production Engineering (WZL) RWTH Aachen University Aachen Germany Fraunhofer-Institute for Production Technology IPT Aachen Germany

ISBN: (纸本)9781509035953

Companies are adapting their traditional development processes, aiming for project-specific designs that are referred to as “Agile Product Development” - flexible, adaptive and accelerated processes. Implementing these principles supports developers to react to challenges such as shortened innovation cycles and increased market dynamics. The project-specific tailoring of a development process has to be carried out right from the start. Early on, companies have to create a unique path for each development project by choosing the right development approach - plan-driven, agile or hybrid -, assembling properly skilled development teams and creating an enabling environment and applicable process design. But, due to the lack of appropriate methodologies for a project-specific tailoring, companies find it difficult to adjust development methods according to the project requirements at hand. Therefore, development projects often do not meet expected budgets, deadlines or product goals. As a first step, the authors present a selection of essential development method elements based on a literature review. These elements, classified in content- and process-related elements, form the basis for a comprehensive method framework. The method framework supports companies in identifying and configuring crucial method elements based on which project-specific development strategies can be derived.

关键词： technology management Technological innovation Adaptation models Complexity theory Personnel Software Life estimation

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Development of a Dynamic Substructuring Framework to Facilitate in Situ Machining Solutions Using Mobile machine tools

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Procedia Manufacturing 2015年 1卷 756-767页

作者： Mohit Law Hendrik Rentzsch Steffen Ihlenfeldt Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany

In situ machining of large parts using mobile machines that are moved to part location(s) allows these parts to be machined, repaired and maintained directly on the site of operation. However, every new part and location that the machine is moved to results in different boundary conditions for the machine-part system which singularly influences the dynamics of the combined system and makes for difficult planning of first-time right machining solutions. To facilitate the planning of in situ machining solutions, this paper presents a dynamic substructuring framework that can predict assembled system dynamics by combining measured and/or modelled substructural response of the individual components under varying base/part/contact/configuration characteristics. Substructural coupling is formulated in the frequency and the continuous-time domains for representative examples of the mobile machine being connected to two different part/base models. The frequency based substructuring approach is used to predict tool point dynamics, results of which are instructive for designing of machining strategies to ensure stable productive cutting conditions. State-space substructural coupling predicts the changing nature of the plant model under the varying influences, which provides guidelines for designing appropriate control strategies and selection of appropriate CNC control parameters. Methods presented aid establishment of experimental guidelines for planning of first-time right in situ machining solutions.

关键词： Dynamic substructuring mobile machine tool in situ machining varying boundary conditions receptances state-space coupling modular synthesis mutability

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