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Dynamics of a driven harmonic oscillator coupled to pairwise interacting Ising spins in random fields

Physical Review E 2021年第5期104卷 054212-054212页

作者： Paul Zech Andreas Otto Günter Radons Institute of Physics Chemnitz University of Technology 09107 Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany Institute of Mechatronics Reichenhainer Str. 88 09126 Chemnitz Germany

In general we are interested in dynamical systems coupled to complex hysteresis. Therefore as a first step we investigated recently the dynamics of a periodically driven damped harmonic oscillator coupled to independent Ising spins in a random field. Although such a system does not produce hysteresis, we showed how to characterize the dynamics of such a piecewise-smooth system, especially in the case of a large number of spins [Zech, Otto, and Radons, Phys. Rev. E 101, 042217 (2020)]. In this paper we extend our model to spin dimers, thus pairwise interacting spins. We show in which cases two interacting spins can show elementary hysteresis, and we give a connection to the Preisach model, which allows us to consider an infinite number of spin pairs. This thermodynamic limit leads us to a dynamical system with an additional hysteretic force in the form of a generalized play operator. By using methods from general chaos theory, piecewise-smooth system theory, and statistics we investigate the chaotic behavior of the dynamical system for a few spins and also in the case of a larger number of spins by calculating bifurcation diagrams, Lyapunov exponents, fractal dimensions, and self-averaging properties. We find that the fractal dimensions and the magnetization are in general not self-averaging quantities. We show how the dynamical properties of the piecewise-smooth system for a large number of spins differs from the system in its thermodynamic limit.

关键词： Bifurcations Chaos Spin dynamics Chaotic systems Ising model Phase space methods

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Comparison of Resistive and Optical Strain Measurement for Early Fracture Detection

Comparison of Resistive and Optical Strain Measurement for E...

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作者： Carabello, Alina Neupetsch, Constanze Werner, Michael Rotsch, Christian Drossel, Welf-Guntram Zajonz, Dirk Chemnitz University of Technology Adaptronics and Lightweight Design in Production Chemnitz Germany Fraunhofer Institute for Machine Tools and Forming Technology Iwu Chemnitz/ Dresden Germany Zeisigwaldkliniken Bethanien Chemnitz Germany

To increase learning success in surgical training, physical simulators are supplemented by measurement technology to generate and record objective feedback and error detection. An opportunity to detect fractures following hip stem implantation early can be measurement of occurring strains on bone surface. These strains can be determined while using strain gauges, digital image correlation (DIC) or photoelasticity. In this research strain gauges and DIC were compared regarding their suitability as strain measurement tools for use in physical simulators. Therefore a testing method was described to replicate the implantation of a hip stem. Testing devices modelled on a realistic prosthesis were pressed into prepared porcine femora in a two-step procedure with a material testing machine. The local strains occurring on bone surface were determined using an optical measurement system for DIC and strain gauges. The initial fractures in the tested femora are located medial-anterior in most cases (73,6%). With increasing indentation depth of the test device, the strains on bone surface increase. Comparing the local strains determined by DIC and strain gauges consistencies in curves are noticeable. Maximal determined strains before fracturing amount to 0,69% with strain gauges and 0,75% with DIC. In the range of the fracture gap, strain gradients are determined by using DIC. However the detected surfaces are of low quality caused by gaps and motion artefacts. The results show strains on bone surfaces for early fracture detection are measurable with strain gauges and DIC. DIC is assessed as less suitable compared to strain gauges. Furthermore strain gauges have greater level of integration and economic efficiency, so they are preferred the use in surgical training simulators. © 2020 by Walter de Gruyter Berlin/Boston 2020.

关键词： Image correlation

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Digital innovation hubs for robotics - TRINITY approach for distributing knowledge via modular use case demonstrations 8

Digital innovation hubs for robotics - TRINITY approach for ...

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8th CIRP Conference of Assembly technology and Systems, CATS 2020

作者： Lanz, Minna Reimann, Jan Ude, Aleš Kousi, Niki Pieters, Roel Dianatfar, Morteza Makris, Sotiris Tampere University Tampere Finland Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany Jožef Stefan Institute Ljubljana Slovenia University of Patras Patras Greece

Robots are no longer stand-alone systems on the factory floor. The demand for industrial robots (market) is anticipated to be growing to 65 billion euros by the year 2023. Within all areas of robotics, the demand for collaborative and more flexible systems is rising as well. The level of desired collaboration and increased flexibility will only be reached if the systems are developed as a whole, e.g. perception, reasoning and physical manipulation. The rising need for collaborative robots in the automation industry is acting as a driver for this market and is expected to serve as a market opportunity for future growth. However, at the same time especially smaller companies have difficulties to formulate a concrete vision and strategies for the uptake of robotics, finding skilled workforce to develop and deploy the robot systems and/or work in the manufacturing industry. A number of Digital Innovation Hubs (DIHs) have been developed to enhance the knowledge and technology transfer from laboratories to factory floors, mitigating the skills gap and supporting the formulation of innovation ecosystems with the specific focus on small and medium-sized companies around Europe. The main aim of this paper is to introduce the concept and approach taken in H2020 TRINITY-project that aims to develop a Robotics Innovation Hub focused on Agile Production. The paper will introduce the concept and technical approach of the project, and discusses the preliminary results, challenges and opportunities of these kind of DIHs. © 2020 The Author(s).

关键词： Industrial robots

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Metal Foams with Ceramic Inserts for Security Applications 11th

Metal Foams with Ceramic Inserts for Security Applications

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11th International Conference on Porous Metals and Metallic Foams, MetFoam 2019

作者： Vogel, René Drebenstedt, Claudia Szyniszewski, Stefan Bittner, Florian Fras, Teresa Blanc, Ludovic Fraunhofer Institute for Machine Tools and Forming Technology IWU Chemnitz Germany University of Surrey Guildford United Kingdom Fraunhofer Institute for Wood Research Wilhelm-Klauditz-Institut WKI Hannover Germany Saint-Louis France

ISBN: (纸本)9783030427979

Protective performance and a low weight of armour plates are the most important objective in security applications. Metallic foams can provide a high level of protection without an extensive mass and were used as a part of various laminated armour systems in the past. Embedding small ceramic parts in metallic foam combines the hardness of ceramics with the flexibility of the lightweight cellular matrix. The material has an extreme cutting resistance against mechanical tools such as angle grinder, drill bits, or other cutting devices. In several testing campaigns, aluminium foams were combined with different internal layouts of stacked or integrated ceramics. The cellular core was foamed directly to steel cover sheets or was bonded to different steel alloy faceplates. In additional tests, blast wave propagation of the metallic foam ceramic composite (MFCC) panels was evaluated. Furthermore, several ballistic tests were performed and compared to state-of-the-art armour materials. It was possible to achieve better performance in this comparison to standard armoured steel at a lower overall weight. © 2020, The Minerals, Metals & Materials Society.

关键词： Metals

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Examination of the variance in human pathways in HRC with heavy duty-robots for safe process planning

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Procedia CIRP 2020年 88卷 234-239页

作者： Mohamad Bdiwi Ann-Kathrin Harsch Paul Reindel Matthias Putz Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainerstr. 88 09126 Chemnitz Germany

Compared to robots, human pathways are individually changeable. Particularly the human-robot-collaboration (HRC) with heavy-duty robots carry high risk potentials. To ensure safety and efficiency, the human variance in pathways should be determined in the planning of HRC. Hence this paper presents a method to investigate human pathway variations in a real study. In systematically selected tasks, human pathways are examined for 100 participants in manual and human-robot collaboration (HRC) scenarios. As a result, the variations of pathways are presented depending on various features: in nearly all cases the variance of women’s walking pathways is smaller than that of men.

关键词： Human factors Production planning Human-Robot-Collaboration (HRC)

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The Challenge of Open Cellular Metal Foam Production 11th

The Challenge of Open Cellular Metal Foam Production

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11th International Conference on Porous Metals and Metallic Foams, MetFoam 2019

作者： Hannemann, Christian Uhlig, Mandy Hipke, Thomas Meier, Iris Fraunhofer-Institute for Machine Tools and Forming Technology Reichenhainer Str. 88 Chemnitz09126 Germany

ISBN: (纸本)9783030427979

Five years ago fraunhofer-iwu started research in open cellular metal structures as the potential applications increased based upon their exceptional properties. Heat exchangers, filters, and battery electrodes are examples of potential applications. As casted aluminum foams were in serial production and fraunhofer in close cooperation with the manufacturer, the interest was limited to prototyping of individual foams especially in combination with solid regions for fixing, encasing, or sub-division. New parameter combinations and technological processes were developed and the advantages, limitations, and potentials are described within this document. Alternatively, galvanic coating of PUR foams with copper, nickel, and other metals is common, again buyable and state of the art. R&D activities related to application development and adapted geometries not yet realizable by conventional mass production will be shown. Investigations for graded strut-structures and cylindrical tube-like parts were intensified to reach serial production level. The lecture represents investigations, results, dropped, and new approaches of all routes. © 2020, The Minerals, Metals & Materials Society.

关键词： Metal foams

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Application of Fourier-related data reduction methods in sheet metal forming

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Procedia CIRP 2021年 99卷 260-265页

作者： Christian Schwarz Patrick Link Steffen Ihlenfeldt Welf-Guntram Drossel Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Strasse 88 Chemnitz 09126 Germany Institute of Mechatronic Engineering TU Dresden Helmholtzstrasse 7a Dresden 01062 Germany Institute for Machine Tools and Production Processes TU Chemnitz Reichenhainer Strasse 70 Chemnitz 09126 Germany

Due to the increasing digitalization, modern solutions are needed to work effectively with rapidly growing amounts of data in the automotive production. This paper shows two potential fields of application for the practical use of data reduction methods. In particular, the combination of Fourier-related transformation methods (e.g. discrete Fourier transform) and surrogate models for the useful 3D visualization of complex interrelationships is shown using the example of press hardening and deep drawing.

关键词： Press hardening Deep drawing FEM Sensitivity analysis Discrete Fourier Transform (DFT) Discrete Cosin Transform (DCT)

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An investigation of abrasive waterjet machining of cubic boron nitride (CBN) with a softer abrasive material

An investigation of abrasive waterjet machining of cubic bor...

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20th CIRP Conference on Electro Physical and Chemical Machining, ISEM 2020

作者： Morczinek, F. Putz, M. Chemnitz University of Technology Reichenhainer Str. 70 Chemnitz09126 Germany Fraunhofer Institute for Machine Tools an Forming Technology IWU Reichenhainer Str. 88 Chemnitz09126 Germany

For an effective machining of high-performance materials, high-strength cutting materials, e.g. cubic boron nitride (CBN), with high resistance to any kind of wear are used. However, these materials must also be able to be machined in order to produce geometric elements such as chip breakers or chip grooves. According to the current state of the art, grinding and laser beam technology are used for this purpose. In this paper, an attempt was made to use the erosive removal mechanism of abrasive water jet technology to cut a harder material with a softer abrasive. Within the framework of a full factorial test plan, the removal rate, the macroscopic kerf geometry on CBN were investigated by means of abrasive water jet machining. It could be proven that it is possible to remove a harder material with a softer abrasive by means of abrasive water jet technology. © 2020 The Authors. Published by Elsevier B.V.

关键词： Abrasion

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Position and force controlled pneumatic chuck for high precision machining 21

Position and force controlled pneumatic chuck for high preci...

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21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021

作者： Eckert, Udo Ben-Hanan, Uri Koriath, Hans-Joachim Mende, Mattias Weiss, Avi Wertheim, Rafi Azaria, Udi Fraunhofer Institute for Machine Tools and Forming Technology Chemnitz09126 Germany ORT Braude College Snunit Street 51 PO Box 78 Karmiel2161002 Israel Henri Azaria PAL Ltd.

ISBN: (纸本)9780995775190

This paper presents the development of a clamping system, including force controlled jaws, a method for position and orientation control in the XY, XZ and YZ planes, based on a visual pattern identification and a numerical compensation of the workpiece position, integrated into the machine tool control unit. Reproducible correction of workpiece position and orientation were investigated, evaluated, and combined to form the new adaptive workpiece clamping system to ensure accurate positioning and clamping repeatability. The developed system is made of an air (pneumatic) chuck with 3 clamping jaws, used for holding the workpiece with a defined clamping force, controlled by air pressure. A tilting device combined with a rotating table for inclination adjustment of the XY plane, controlled by the vision identification device, is used to measure and correct the position and orientation of the workpiece. A developed algorithm for X and Y motion of the machine tool axes as a function of the visually identified values enables repositioning of the workpiece after re-clamping. The clamping forces are measured by strain gauges. The design of the associated jaws is based on FEM analysis to ensure small elastic deformations, allowing for accurate clamping forces. The visual identification of the workpiece position and movement algorithm were tested with the pneumatic chuck on a high precision CNC machine tool. The developed system provided in X and Y direction a repeatability of pattern positioning within 1.1 µm, which is three times better compared to the initial chuck reclamping repeatability. © 2021 Proceedings of the 21st International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

关键词： Pneumatics

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Synergy Analysis and verification of connected Cyber Physical Systems using virtual commissioning

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Procedia CIRP 2021年 99卷 639-644页

作者： Christoph Allmacher Anna Seiderer Philipp Klimant Michael Kuhl Institute for Machine Tools and Production Processes Chemnitz University of Technology Reichenhainer Str. 70 09126 Chemnitz Germany Mittweida University of Applied Sciences Technikumplatz 17 09648 Mittweida Germany Fraunhofer Institute for Machine Tools and Forming Technology IWU Reichenhainer Str. 88 09126 Chemnitz Germany

The design of cyber physical systems in today’s production and intralogistics is influenced by the increasing availability and exchange of data. On the one hand, synergies between connected systems can be used to develop lightweight applications by sharing and reusing data. On the other hand, the possible combinations between these systems increase the complexity and design options. This paper presents a method to structure possible design options systematically and proposes virtual commissioning as solution for their analysis and verification to enable early design decisions. The method is demonstrated using an automated guided vehicle combined with a tactile warning device.

关键词： Virtual commissioning Automated guided vehicle Tactile warning device

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