@inproceedings{22724,
abstract = {{
Predictive Maintenance as a desirable maintenance strategy in industrial applications relies on suitable condition monitoring solutions to reduce costs and risks of the monitored technical systems. In general, those solutions utilize model-based or data-driven methods to diagnose the current state or predict future states of monitored technical systems. However, both methods have their advantages and drawbacks. Combining both methods can improve uncertainty consideration and accuracy. Different combination approaches of those hybrid methods exist to exploit synergy effects. The choice of an appropriate approach depends on different requirements and the goal behind the selection of a hybrid approach.
In this work, the hybrid approach for estimating remaining useful lifetime takes potential uncertainties into account. Therefore, a data-driven estimation of new measurements is integrated within a model-based method. To consider uncertainties within the system, a differentiation between different system behavior is realized throughout diverse states of degradation.
The developed hybrid prediction approach bases on a particle filtering method combined with a machine learning method, to estimate the remaining useful lifetime of technical systems. Particle filtering as a Monte Carlo simulation technique is suitable to map and propagate uncertainties. Moreover, it is a state-of-the-art model-based method for predicting remaining useful lifetime of technical systems. To integrate uncertainties a multi-model particle filtering approach is employed. In general, resampling as a part of the particle filtering approach has the potential to lead to an accurate prediction. However, in the case where no future measurements are available, it may increase the uncertainty of the prediction. By estimating new measurements, those uncertainties are reduced within the data-driven part of the approach. Hence, both parts of the hybrid approach strive to account for and reduce uncertainties.
Rubber-metal-elements are employed as a use-case to evaluate the developed approach. Rubber-metal-elements, which are used to isolate vibrations in various systems, such as railways, trucks and wind turbines, show various uncertainties in their behavior and their degradation. Those uncertainties are caused by diverse inner and outer factors, such as manufacturing influences and operating conditions. By expert knowledge the influences are described, analyzed and if possible reduced. However, the remaining uncertainties are considered within the hybrid prediction method. Relative temperature is the selected measurand to describe the element’s degradation. In lifetime tests, it is measured as the difference between the element’s temperature and the ambient temperature. Thereby, the influence of the ambient temperature on the element’s temperature is taken into account. Those elements show three typical states of degradation that are identified within the temperature measurements. Depending on the particular state of degradation a new measurement is estimated within the hybrid approach to reduce potential uncertainties.
Finally, the performance of the developed hybrid method is compared to a model-based method for estimating the remaining useful lifetime of the same elements. Suitable performance indices are implemented to underline the differences between the results.}},
author = {{Bender, Amelie and Sextro, Walter}},
booktitle = {{Proceedings of the European Conference of the PHM Society 2021}},
editor = {{Do, Phuc and King, Steve and Fink, Olga}},
keywords = {{Hybrid prediction method, Multi-model particle filtering, Uncertainty quantification, RUL estimation}},
number = {{1}},
title = {{{Hybrid Prediction Method for Remaining Useful Lifetime Estimation Considering Uncertainties}}},
doi = {{https://doi.org/10.36001/phme.2021.v6i1.2843 }},
volume = {{6}},
year = {{2021}},
}
@article{21232,
author = {{Itner, Dominik and Gravenkamp, Hauke and Dreiling, Dmitrij and Feldmann, Nadine and Henning, Bernd}},
issn = {{0041-624X}},
journal = {{Ultrasonics}},
title = {{{Efficient semi-analytical simulation of elastic guided waves in cylinders subject to arbitrary non-symmetric loads}}},
doi = {{10.1016/j.ultras.2021.106389}},
year = {{2021}},
}
@inbook{29936,
author = {{Ramaswami, Arjun and Kenter, Tobias and Kühne, Thomas and Plessl, Christian}},
booktitle = {{Applied Reconfigurable Computing. Architectures, Tools, and Applications}},
isbn = {{9783030790240}},
issn = {{0302-9743}},
publisher = {{Springer International Publishing}},
title = {{{Evaluating the Design Space for Offloading 3D FFT Calculations to an FPGA for High-Performance Computing}}},
doi = {{10.1007/978-3-030-79025-7_21}},
year = {{2021}},
}
@article{37547,
author = {{Vochatzer, Stefanie and Engelmann , Sebastian }},
journal = {{Journal der Schreibwissenschaft}},
number = {{22}},
pages = {{52--63}},
publisher = {{WBV}},
title = {{{ Autoethnografie und Kreatives Schreiben}}},
doi = {{10.3278/JOS2102W052}},
volume = {{3}},
year = {{2021}},
}
@article{51202,
abstract = {{When joining lightweight parts of various materials, clinching is a cost efficient solution. In a production line, the quality of a clinch point is primarily controlled by measurement of dimensions, which are accessible from outside. However, methods such as visual testing and measuring the bottom thickness as well as the outer diameter are not able to deliver any information about the most significant geometrical characteristic of the clinch point, neck thickness and undercut. Furthermore, ex-situ destructive methods such as microsectioning cannot detect elastic deformations and cracks that close after unloading. In order to exceed the current limits, a new non-destructive in-situ testing method for the clinching process is necessary. This work proposes a concept to characterize clinch points in-situ by combining two complementary non-destructive methods, namely, computed tomography (CT) and ultrasonic testing. Firstly, clinch points with different geometrical characteristics are analysed experimentally using ex-situ CT to get a highly spatially resolved 3D-image of the object. In this context, highly X-ray attenuating materials enhancing the visibility of the sheet-sheet interface are investigated. Secondly, the test specimens are modelled using finite element method (FEM) and a transient dynamic analysis (TDA) is conducted to study the effect of the geometrical differences on the deformation energy and to qualify the TDA as a fast in-situ non-destructive method for characterizing clinch points at high temporal resolution.}},
author = {{Köhler, Daniel and Sadeghian, Behdad and Kupfer, Robert and Troschitz, Juliane and Gude, Maik and Brosius, Alexander}},
issn = {{1662-9795}},
journal = {{Key Engineering Materials}},
keywords = {{Mechanical Engineering, Mechanics of Materials, General Materials Science}},
pages = {{89--96}},
publisher = {{Trans Tech Publications, Ltd.}},
title = {{{A Method for Characterization of Geometric Deviations in Clinch Points with Computed Tomography and Transient Dynamic Analysis}}},
doi = {{10.4028/www.scientific.net/kem.883.89}},
volume = {{883}},
year = {{2021}},
}
@article{51199,
abstract = {{AbstractRecent developments in automotive and aircraft industry towards a multi-material design pose challenges for modern joining technologies due to different mechanical properties and material compositions of various materials such as composites and metals. Therefore, mechanical joining technologies like clinching are in the focus of current research activities. For multi-material joints of metals and thermoplastic composites thermally assisted clinching processes with advanced tool concepts are well developed. The material-specific properties of fibre-reinforced thermoplastics have a significant influence on the joining process and the resulting material structure in the joining zone. For this reason, it is important to investigate these influences in detail and to understand the phenomena occurring during the joining process. Additionally, this provides the basis for a validation of a numerical simulation of such joining processes. In this paper, the material structure in a joint resulting from a thermally assisted clinching process is investigated. The joining partners are an aluminium sheet and a thermoplastic composite (organo sheet). Using computed tomography enables a three-dimensional investigation that allows a detailed analysis of the phenomena in different joining stages and in the material structure of the finished joint. Consequently, this study provides a more detailed understanding of the material behavior of thermoplastic composites during thermally assisted clinching.}},
author = {{Gröger, Benjamin and Köhler, Daniel and Vorderbrüggen, Julian and Troschitz, Juliane and Kupfer, Robert and Meschut, Gerson and Gude, Maik}},
issn = {{0944-6524}},
journal = {{Production Engineering}},
keywords = {{Industrial and Manufacturing Engineering, Mechanical Engineering}},
number = {{2-3}},
pages = {{203--212}},
publisher = {{Springer Science and Business Media LLC}},
title = {{{Computed tomography investigation of the material structure in clinch joints in aluminium fibre-reinforced thermoplastic sheets}}},
doi = {{10.1007/s11740-021-01091-x}},
volume = {{16}},
year = {{2021}},
}
@article{23431,
abstract = {{As an effective and accurate method for modelling composite materials, mean-field homogenization is still not well studied in modelling non-linear and damage behaviours of UD composites. Investigated micro FE-simulations show that the matrix of UD composites exhibits different average plastic behaviour, named as average asymmetric matrix plasticity (AAMP), when the composite behaves different under shear, longitudinal and transverse loadings. In this study, a non-linear mean-field debonding model (NMFDM) combining a mean-field model and a fibre–matrix interface debonding model, is developed to simulate UD composites under consideration of AAMP, fibre–matrix interface damage and progressive failure. AAMP is considered by using so-called stress mode factor, which is expressed in terms of basic invariants of the matrix deviatoric stress tensor and is used as an indicator for detection of differences in the loading mode. The material behaviour of UD composites with imperfect interface is assumed identical as for perfect interface and stiffness reduced fibres. Progressive failure criteria are established with consideration of fibre breakage and matrix crack for different fibre orientations. As a representative example for the NMFDM, a C30/E201 UD composite is studied. To verify the model, experiments are conducted on polymers, carbon fibres and UD CFRPs. Finally, the model is applied to simulate a perforated CFRP laminate, which shows excellent prediction ability on deformation, debonding and progressive failure.}},
author = {{Cheng, C. and Wang, Z. and Jin, Z. and Ju, X. and Schweizer, Swetlana and Tröster, Thomas and Mahnken, Rolf}},
issn = {{1359-8368}},
journal = {{Composites Part B: Engineering}},
keywords = {{Non-linear mean-field homogenization Average asymmetric plasticity of matrix Fibre–matrix interface debonding Micro-mechanical FE-simulation Progressive failure}},
title = {{{Non-linear mean-field modelling of UD composite laminates accounting for average asymmetric plasticity of the matrix, debonding and progressive failure}}},
doi = {{10.1016/j.compositesb.2021.109209}},
volume = {{224}},
year = {{2021}},
}
@inproceedings{24159,
abstract = {{The online fitting of a microscopic traffic simulation model to reconstruct the current state of a real traffic
area can be challenging depending on the provided data. This paper presents a novel method based on limited
data from sensors positioned at specific locations and guarantees a general accordance of reality and
simulation in terms of multimodal road traffic counts and vehicle speeds. In these considerations, the actual
purpose of research is of particular importance. Here, the research aims at improving the traffic flow by
controlling the Traffic Light Systems (TLS) of the examined area which is why the current traffic state and
the route choices of individual road users are the matter of interest. An integer optimization problem is derived
to fit the current simulation to the latest field measurements. The concept can be transferred to any road traffic
network and results in an observation of the current multimodal traffic state matching at the given sensor
position. First case studies show promosing results in terms of deviations between reality and simulation.}},
author = {{Malena, Kevin and Link, Christopher and Mertin, Sven and Gausemeier, Sandra and Trächtler, Ansgar}},
booktitle = {{VEHITS 2021 Proceedings of the 7th International Conference on Vehicle Technology and Intelligent Transport Systems}},
isbn = {{978-989-758-513-5}},
keywords = {{Microscopic Traffic Simulation, Online State Estimation, Mixed Road Users, Sensor Fusion, Integer Programming, Route Choice, Vehicle2Infrastructure}},
location = {{Online Streaming}},
pages = {{386--395}},
publisher = {{SCITEPRESS}},
title = {{{Online State Estimation for Microscopic Traffic Simulations using Multiple Data Sources*}}},
volume = {{7}},
year = {{2021}},
}
@inproceedings{24166,
abstract = {{This paper deals with a novel method for the online fitting of a microscopic traffic simulation model to the current state of a real world traffic area. The traffic state estimation is based on limited data of different measurement sources and guarantees general accordance of reality and simulation in terms of multimodal road traffic counts and vehicle speeds. The research is embedded in the challenge of improving the traffic by controlling the traffic light systems (TLS) of the examined area. Therefore, the current traffic state and the predicted route choices of individual road users are the matter of interest. The concept is generally transferable to any road traffic system. To give an impression of the accuracy and potential of the approach, the validation and first application results are presented.}},
author = {{Malena, Kevin and Link, Christopher and Mertin, Sven and Gausemeier, Sandra and Trächtler, Ansgar}},
booktitle = {{2021 IEEE Transportation Electrification Conference & Expo (ITEC)}},
isbn = {{978-1-7281-7584-3}},
publisher = {{IEEE}},
title = {{{Validation of an Online State Estimation Concept for Microscopic Traffic Simulations◆}}},
doi = {{10.1109/itec51675.2021.9490087}},
year = {{2021}},
}
@article{22272,
abstract = {{The number of multi-material joints is increasing as a result of lightweight design. Self-piercing riveting (SPR) is an important mechanical joining technique for multi-material structures. Rivets for SPR are coated to prevent corrosion, but this coating also influences the friction that prevails during the joining process. The aim of the present investigation is to evaluate this influence. The investigation focuses on the common rivet coatings Almac® and zinc-nickel with topcoat as well as on uncoated rivet surfaces. First of all, the coating thickness and the uniformity of the coating distribution are analysed. Friction tests facilitate the classification of the surface properties. The influence of the friction on the characteristic joint parameters and the force-stroke curves is analysed by means of experimental joining tests. More in-depth knowledge of the effects that occur is achieved through the use of numerical simulation. Overall, it is shown that the surface condition of the rivet has an impact on the friction during the joining process and on the resulting joint. However, the detected deviations between different surface conditions do not restrict the operational capability of SPR and the properties of uncoated rivet surfaces, in particular, are similar to those of Almac®-coated rivets. It can thus be assumed that SPR with respect to the joining process is also possible without rivet coating in principle.}},
author = {{Uhe, Benedikt and Kuball, Clara-Maria and Merklein, Marion and Meschut, Gerson}},
journal = {{Key Engineering Materials}},
keywords = {{Coating, Friction, Joining}},
pages = {{11--18}},
title = {{{Influence of the Rivet Coating on the Friction during Self-Piercing Riveting}}},
doi = {{10.4028/www.scientific.net/KEM.883.11}},
volume = {{883}},
year = {{2021}},
}
@phdthesis{6563,
abstract = {{Designprozesse von Schallwandlern werden durch zunehmende Rechenkapazitäten immer mehr durch simulative Betrachtungen unterstützt. Dabei ist vor allem die Wahl der Materialparameter der verwendeten Materialien wichtig für ein realitätsnahes Simulationsergebnis. Bei Schallwandlern werden häufig Piezokeramiken als aktive Elemente genutzt, welche sich durch eine Verkopplung mechanischer und elektrischer Eigenschaften auszeichnen. Zur Bestimmung ihrer Materialparameter stellt der IEEE Standard on Piezoelectricity ein standardisiertes Verfahren dar. Dazu sind fünf Impedanzmessungen an vier unterschiedlich gefertigten Probekörpergeometrien notwendig. Da an jedem einzelnen Probekörper nur eine Untermenge aller notwendigen Materialparameter bestimmt werden kann, werden diese dann zu einem kompletten Materialparametersatz zusammengefügt. Aufgrund der unterschiedlichen Prozessbedingungen, bei denen die jeweiligen Probekörper hergestellt werden, ist dieser Materialparametersatz jedoch inkonsistent und kann nie das Verhalten einer einzelnen Probe beschreiben. Daher wird in der vorliegenden Arbeit ein Messverfahren entwickelt, mit dem es möglich ist, alle relevanten Materialparameter unter besonderer Berücksichtigung von Dämpfung an einem einzelnen Probekörper allein durch Impedanzmessungen zu bestimmen. Als Probekörper wird dazu eine in der Anwendung häufig verwendete Scheibengeometrie verwendet. Um eine hinreichend hohe Sensitivität auf alle Materialparameter zu gewährleisten, wird diese mit einer optimierten Elektrodentopologie gefertigt. Da in diesem Fall keine analytische Betrachtung mehr möglich ist, wird das Messverfahren durch einen inversen Ansatz realisiert.}},
author = {{Feldmann, Nadine}},
pages = {{184}},
publisher = {{Universität Paderborn}},
title = {{{ Ein modellbasiertes Messverfahren zur Charakterisierung von Piezokeramiken unter Verwendung eines einzelnen scheibenförmigen Probekörpers}}},
doi = {{10.17619/UNIPB/1-1264}},
year = {{2021}},
}
@article{21341,
abstract = {{The progress in numerical methods and simulation tools promotes the use of inverse problems in material characterisation problems. A newly developed procedure can be used to identify the behaviour of piezoceramic discs over a wide frequency range using a single specimen via fitting simulated and measured impedances by optimising the underlying material parameters. Since there is no generally accepted damping model for piezoelectric ceramics, several mechanical damping models are examined for the material identification. Three models have been chosen and their ability to replicate the measured impedances is evaluated. On the one hand, the common Rayleigh model is considered as a reference. On the other hand, a Zener model and a model using complex constants are extended to model the transversely isotropic material. As the Rayleigh model is only valid for a limited frequency range, it fails to model the broadband behaviour of the material. The model using complex constants leads to the best fit over a wide frequency range while at the same time only adding three additional parameters for modelling damping. Thus, damping can be assumed approximately frequency-independent in piezoceramics.}},
author = {{Feldmann, Nadine and Schulze, Veronika and Claes, Leander and Jurgelucks, Benjamin and Meihost, Lars and Walther, Andrea and Henning, Bernd}},
issn = {{2196-7113}},
journal = {{tm - Technisches Messen}},
number = {{5}},
pages = {{294 -- 302}},
title = {{{Modelling damping in piezoceramics: A comparative study}}},
doi = {{10.1515/teme-2020-0096}},
volume = {{88}},
year = {{2021}},
}
@inproceedings{25265,
abstract = {{Waveguide-based methods can be used for the non-destructive determination of acoustic material parameters. One of these methods is based on transmission measurements of cylindrical polymeric specimens. Here, the experimental setup consists of two transducers, which excite and receive the waveguide modes at the faces of the cylinder. The measurement, as well as a forward model, are used to determine material parameters of the polymeric specimen in an inverse approach.
1-3 piezoelectric composites are used as an active element because they can be approximated by a thickness vibration only. This allows an easy identification of Mason model parameters to characterise the transducers’ vibration behaviour.
However, sensitivity analysis shows a high uncertainty in the determination of the mechanical shear parameters due to the uniform excitation. To increase the sensitivity to these shear motions, arbitrary excitations were investigated by means of numerical simulation.
In order to be able to realise the determined optimal excitation, new transducer prototypes were designed. By subdividing the electrodes of the active element, for example, ring-shaped excitation is feasible. Furthermore, it can be shown that modelling these transducers with a one-dimensional Mason model is sufficient.}},
author = {{Dreiling, Dmitrij and Itner, Dominik and Feldmann, Nadine and Scheidemann, Claus and Gravenkamp, Hauke and Henning, Bernd}},
booktitle = {{Fortschritte der Akustik - DAGA 2021}},
location = {{Wien}},
publisher = {{Deutsche Gesellschaft für Akustik e.V. (DEGA)}},
title = {{{Application and modelling of ultrasonic transducers using 1-3 piezoelectric composites with structured electrodes}}},
year = {{2021}},
}
@unpublished{19603,
abstract = {{Micro- and smart grids (MSG) play an important role both for integrating
renewable energy sources in conventional electricity grids and for providing
power supply in remote areas. Modern MSGs are largely driven by power
electronic converters due to their high efficiency and flexibility.
Nevertheless, controlling MSGs is a challenging task due to highest
requirements on energy availability, safety and voltage quality within a wide
range of different MSG topologies. This results in a high demand for
comprehensive testing of new control concepts during their development phase
and comparisons with the state of the art in order to ensure their feasibility.
This applies in particular to data-driven control approaches from the field of
reinforcement learning (RL), whose stability and operating behavior can hardly
be evaluated a priori. Therefore, the OpenModelica Microgrid Gym (OMG) package,
an open-source software toolbox for the simulation and control optimization of
MSGs, is proposed. It is capable of modeling and simulating arbitrary MSG
topologies and offers a Python-based interface for plug \& play controller
testing. In particular, the standardized OpenAI Gym interface allows for easy
RL-based controller integration. Besides the presentation of the OMG toolbox,
application examples are highlighted including safe Bayesian optimization for
low-level controller tuning.}},
author = {{Bode, Henrik and Heid, Stefan Helmut and Weber, Daniel and Hüllermeier, Eyke and Wallscheid, Oliver}},
booktitle = {{arXiv:2005.04869}},
title = {{{Towards a Scalable and Flexible Simulation and Testing Environment Toolbox for Intelligent Microgrid Control}}},
year = {{2020}},
}
@inproceedings{19606,
abstract = {{Mobile shopping apps have been using Augmented Reality (AR) in the last years to place their products in the environment of the customer. While this is possible with atomic 3D objects, there is is still a lack in the runtime configuration of 3D object compositions based on user needs and environmental constraints. For this, we previously developed an approach for model-based AR-assisted product configuration based on the concept of Dynamic Software Product Lines. In this demonstration paper, we present the corresponding tool support ProConAR in the form of a Product Modeler and a Product Configurator. While the Product Modeler is an Angular web app that splits products (e.g. table) up into atomic parts (e.g. tabletop, table legs, funnier) and saves it within a configuration model, the Product Configurator is an Android client that uses the configuration model to place different product configurations within the environment of the customer. We show technical details of our ready to use tool-chain ProConAR by describing its implementation and usage as well as pointing out future research directions.}},
author = {{Gottschalk, Sebastian and Yigitbas, Enes and Schmidt, Eugen and Engels, Gregor}},
booktitle = {{Human-Centered Software Engineering. HCSE 2020}},
editor = {{Bernhaupt, Regina and Ardito, Carmelo and Sauer, Stefan}},
keywords = {{Product Configuration, Augmented Reality, Model-based, Tool Support}},
location = {{Eindhoven}},
publisher = {{Springer}},
title = {{{ProConAR: A Tool Support for Model-based AR Product Configuration}}},
doi = {{10.1007/978-3-030-64266-2_14}},
volume = {{12481}},
year = {{2020}},
}
@inproceedings{19738,
author = {{Wende, Marc and Philippi, Kai and Kenig, Eugeny}},
booktitle = {{10. ProcessNet-Jahrestagung und 34. DECHEMA-Jahrestagung der Biotechnologen }},
location = {{Aachen}},
title = {{{Numerische Simulation von Gravidestillationsapparaten zur Trennung eines binären Ethanol/Wasser-Gemisches}}},
year = {{2020}},
}
@techreport{20145,
abstract = {{Der Karosseriebau ist zunehmend durch die Verwendung unterschiedlicher Werkstoffe in Mischbauweise gekennzeichnet, was zu einem Einsatz von mechanischen Fügeverfahren geführt hat. Hieraus resultieren die Zielsetzungen, die mechanischen Fügeverfahren in ihrer Effizienz und ihren Einsatzbereichen zu erweitern, sowie die Anzahl der Experimente zu reduzieren und Entwicklungszyklen zu verkürzen. Dies erfolgt mit Unterstützung der numerischen Simulation. Neben der Beschreibung des plastischen Verhaltens gilt es auch, das Schädigungsverhalten abzubilden.
Der Fügeprozess bzw. die Fügerichtung erfolgt senkrecht zur Blechoberfläche und führt somit zu einem dreidimensionalen Zustand der Fügelemente. Hieraus leitet sich die Herausforderung ab, das Werkstoffversagen in Abhängigkeit der Beanspruchungssituation zu beschreiben. Ein einfacher Ansatz zur Abbildung des Durchdringens ist ein geometrisches Trennkriterium.
Ein solches Kriterium basiert i.d.R. auf einem experimentell beobachteten Verhalten und ist somit nicht prognosefähig für Variationen bzgl. Werkzeugkonfigurationen, Blechdicken- und Werkstoffgüten-Kombinationen. In diesem Projekt wird das Schädigungsmodell GISSMO (Generalized Incremental Stress State dependent damage Model) verwendet, um die Entwicklung der duktilen Schädigung zu beschreiben und den Bruchbeginn während des Stanzniet- und Schneidclinchens vorherzusagen.
Der Spannungszustand während der Prozesssimulation wird untersucht und die verschiedenen Schädigungsproben werden experimentell erprobt, um die Versagenskurven zu charakterisieren. Die Versagenskurven werden im Schädigungsmodell GISSMO definiert. Um die Genauigkeit des Modells zu gewährleisten, wird die Verifizierung des Modells durch die Simulation von Schädigungsproben mit dem Schädigungsmodell durchgeführt.
Zur Validierung des Modells wird die Simulation des Fügeprozesses mit dem Schädigungsmodell durchgeführt und die Ergebnisse von Simulation und Experiment verglichen. Darüber hinaus werden Sensitivitätsanalysen durchgeführt, um die Einflüsse der Fertigungsprozesse, der Lackierung und des Diskretisierungsgrades auf das Schädigungsverhalten des Materials zu identifizieren.
Das IGF-Vorhaben „Methodenentwicklung zur Schädigungsmodellierung für die numerische Prozesssimulation mechanischer Fügeverfahren" der Forschungsvereinigung EFB e.V. wurde unter der Fördernummer AiF 19452N über die Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF) im Rahmen des Programms zur Förderung der Industriellen Gemeinschaftsforschung (IGF) vom Bundesministerium für Wirtschaft und Energie aufgrund eines Beschlusses des Deutschen Bundestages gefördert. Der Abschlussbericht ist als EFB-Forschungsbericht Nr. 527 erschienen und bei der EFB-Geschäftsstelle und im Buchhandel erhältlich.}},
author = {{Otroshi, Mortaza and Meschut, Gerson}},
isbn = {{978-3-86776-582-4}},
pages = {{182}},
publisher = {{Europäische Forschungsgesellschaft für Blechverarbeitung e.V.}},
title = {{{Methodenentwicklung zur Schädigungsmodellierung für die numerische Prozesssimulation mechanischer Fügeverfahren}}},
year = {{2020}},
}
@inproceedings{20146,
abstract = {{Joining technology is regarded as a key technology for reducing energy consumption and CO2 imitation as well as the use of innovative materials and development of new, resource-saving products. Punch riveting is a widely used and established joining process in many sectors. The white and brown goods, electrical engineering, construction and, in particular, the automotive industry are some of the sectors mentioned here.
Since the design and assessment of punch rivet components with regard to structural durability can only be carried out experimentally using prototypes due to a lack of experience and calculation concepts, the improvement of this uneconomical and time-consuming procedure is the goal of this contribution.
Therefore, a numerical simulation and design method for cyclically loads punched riveted joints shall be introduced. This concept shall be based on the notch strain concept.
The following steps are necessary to achieve the goal shown above:
Tensile tests on all materials involved in the joint for determination of tensile strength and quasi-static stress-strain curves
Estimation of the cyclic material properties from the tensile strength in order to obtain the strain-life curve and the cyclic stress-strain curve
Estimation of mean stress sensitivity from the tensile strength to conduct an amplitude transformation for variable amplitude loadings.
Execution of a 2D forming simulation of the joining process to determine the geometry and the stresses and degrees of deformation present in the connection
Transferring the results of the forming simulation into a static-mechanical load simulation for determining the relation between the external load and the elastic-plastic strain at the critical point
Estimation of the service life by means of the damage parameter Wöhler curves calculated from the strain-life curve
In order to verify the simulation and calculation method, service life investigations have been carried out on punched riveted components under constant and variable amplitude load.
The test results, as well as the workflow through the fatigue assessment and its accuracy in estimation the fatigue life will be shown in this contribution.}},
author = {{Masendorf, Lukas and Wächter, Michael and Horstmann, Stephan and Otroshi, Mortaza and Esderts, Alfons and Meschut, Gerson}},
isbn = {{978-3-9820591-0-5}},
keywords = {{punch rivet, notch strain conept, structural durability}},
location = {{Darmstadt, Germany}},
publisher = {{Deutscher Verband für Materialforschung und -prüfung e.V.}},
title = {{{Linear damage accumulation of self-pierce riveted joints}}},
year = {{2020}},
}
@article{20233,
abstract = {{The challenge of designing new tunable nonlinear dielectric materials with tailored properties has attracted an increasing amount of interest recently. Herein, we study the effective nonlinear dielectric response of a stochastic paraelectric-dielectric composite consisting of equilibrium distributions of circular and partially penetrable disks (or parallel, infinitely long, identical, partially penetrable, circular cylinders) of a dielectric phase randomly dispersed in a continuous matrix of a paraelectric phase. The random microstructures were generated using the Metropolis Monte Carlo algorithm. The evaluation of the effective permittivity and tunability were carried out by employing either a Landau thermodynamic model or its Johnson’s approximation to describe the field-dependent permittivity of the paraelectric phase and solving continuum-electrostatics equations using finite element calculations. We reveal that the percolation threshold in this composite governs the critical behavior of the effective permittivity and tunability. For microstructures below the percolation threshold, our simulations demonstrate a strong nonlinear behaviour of the field-dependent effective permittivity and very high tunability that increases as a function of dielectric phase concentration. Above the percolation threshold, the effective permittivity shows the tendency to linearization and the tunability dramatically drops down. The highly reduced permittivity and extraordinarily high tunability are obtained for the composites with dielectric impenetrable disks at high concentrations, in which the triggering of the percolation transition is avoided. The reported results cast light on distinct nonlinear behaviour of 2D and 3D stochastic composites and can guide the design of novel composites with the controlled morphology and tailored permittivity and tunability.}},
author = {{Myroshnychenko, Viktor and Smirnov, Stanislav and Jose, Pious Mathews Mulavarickal and Brosseau, Christian and Förstner, Jens}},
issn = {{1359-6454}},
journal = {{Acta Materialia}},
pages = {{116432}},
title = {{{Nonlinear dielectric properties of random paraelectric-dielectric composites}}},
doi = {{10.1016/j.actamat.2020.10.051}},
volume = {{203}},
year = {{2020}},
}
@inproceedings{20273,
author = {{Biegler, Max and Rethmeier, Michael and Böhne, Christoph and Meschut, Gerson}},
booktitle = {{Joining in Car Body Engineering}},
title = {{{Resistance spot welding simulation can determine the critical stress- and strain-conditions leading to liquid metal embrittlement formation}}},
year = {{2020}},
}