Dokument-ID Dokumenttyp Autoren/innen Persönliche Herausgeber/innen Haupttitel Abstract Auflage Verlagsort Verlag Herausgeber (Institution) Erscheinungsjahr Titel des übergeordneten Werkes Jahrgang/Band ISBN Veranstaltung Veranstaltungsort Beginndatum der Veranstaltung Enddatum der Veranstaltung Ausgabe/Heft Erste Seite Letzte Seite URN DOI Lizenz Datum der Freischaltung OPUS4-29851 Vortrag Wu, Cheng-Chieh Finite-Elemente-Methode "zu Fuß" 2013 Doktoranden-Kolloquium am Institut für Geodäsie der TU Berlin Doktoranden-Kolloquium am Institut für Geodäsie der TU Berlin Berlin, Germany 2013-05-21 2013-05-21 2016-02-20 OPUS4-29852 Vortrag Wu, Cheng-Chieh Untersuchung neuer Ansätze zur Schadensfrüherkennung an Tragwerken mittels messungs- und modellbasiertem Strukturmonitoring 2013 Doktorandenseminar der Deutschen Geodätischen Kommission Doktorandenseminar der Deutschen Geodätischen Kommission Hanover, Germany 2013-05-23 2013-05-24 2016-02-20 OPUS4-29967 Posterpräsentation Wu, Cheng-Chieh Integration der Finite-Elemente-Methode in die Ausgleichsrechnung zur Parameteridentifikation 2014 17. Internationaler Ingenieursvermessungskurs 2013 17. Internationaler Ingenieursvermessungskurs 2013 Zurich, Switzerland 2014-01-14 2014-01-17 2016-02-20 OPUS4-30174 Beitrag zu einem Tagungsband Neitzel, F.; Weisbrich, S.; Wu, Cheng-Chieh Wieser, A. Integration der Finite-Elemente-Methode in die Ausgleichsrechnung zur Parameteridentifikation Die Strukturüberwachung von Ingenieurbauwerken beruht heutzutage auf einer Auswertung räumlich und zeitlich verteilter hybrider Messungen, die z. B. mittels Tachymeter, Neigungssensoren, faseroptischen Sensoren (FOS), Dehnmessstreifen (DMS), GPS etc. erfasst werden. Für eine gemeinsame Auswertung müssen neue Methoden adaptiert werden, da diese, wie Lienhart (2012) aufzeigt, nur unter Verwendung eines mechanischen 'Bauwerkmodells erfolgen kann. In vielen Ingenieurwissenschaften, wie z. B. dem Bauingenieurwesen, findet die Modellierung physikalisch-mechanischer Eigenschaften von Strukturen mithilfe der Finite-Elemente-Methode (FEM) statt. Die Verifizierung eines derartigen Modells erfolgt vorwiegend lediglich durch stellenweise Messung von z. B. Durchbiegungen und einer anschließenden Gegenüberstellung mit den berechneten Modellwerten. Dies ist meist der Tatsache geschuldet, dass für die FE-Modellierung in der Regel kommerzielle Programme verwendet werden, und somit auf viele Teilprozesse des Auswertealgorithmus nicht zugegriffen werden kann. Aus diesem Grund erfolgt in vielen akademischen Fragestellungen die FE-'Modellierung mit Open-Source-Software, wie z. B. FEniCS (2013) oder OpenSees (2013), wodurch auch eine kombinierte Auswertung von Messungen und Modell nach der Methode 'der kleinsten Quadrate ermöglicht wird. In diesem Beitrag wird eine messungs- und modellbasierte Strukturanalyse (MeMoS) durch (die Integration der Finite-Elemente-Methode in die Ausgleichungsrechnung am Beispiel eines Vier-Punkt-Biegeversuchs vorgestellt. In numerischen Untersuchungen wird gezeigt, wie diese integrierte Analyse für eine Parameteridentifikation angewendet werden kann. Für diese Untersuchungen wird ein Finite-Elemente-Modell mit bekannten Randbedingungen und Materialeigenschaften aufgestellt. Die Durchbiegungen, die als Beobachtungen in die Ausgleichung eingehen, werden mithilfe von Simulationsrechnungen erzeugt; der zu fidentifizierende Parameter ist der Elastizitätsmodul eines Balkens. Es wird untersucht, mit welcher Genauigkeit Durchbiegungsmessungen durchgeführt werden müssen und an welcher Stelle des Bauwerks diese Messungen erfolgen sollen, um den Elastizitätsmodul möglichst genau zu bestimmen. Des Weiteren wird der Einfluss der Anzahl der Messstellen auf den zu identifizierenden Parameter untersucht. Wichmann 2014 17. Internationaler Ingenieurvermessungskurs 14 978-3-87907-535-5 17. Internationaler Ingenieurvermessungskurs Zurich, Switzerland 14.01.2014 17.01.2014 301 310 2016-02-20 OPUS4-55046 Zeitschriftenartikel Wu, Cheng-Chieh; Völker, Daniel; Weisbrich, S.; Neitzel, F. Holl, H. The finite volume method in the context of the finite element method The finite volume method (FVM), like the finite element method (FEM), is a numerical method for determining an approximate solution for partial differential equations. The derivation of the two methods is based on very different considerations, as they have historically evolved from two distinct engineering disciplines, namely solid mechanics and fluid mechanics. This makes FVM difficult to learn for someone familiar with FEM. In this paper we want to show that a slight modification of the FEM procedure leads to an alternative derivation of the FVM. Both numerical methods are starting from the same strong formulation of the problem represented by differential equations, which are only satisfied by their exact solution. For an approximation of the exact solution, the strong formulation must be converted to a so-called weak form. From here on, the two numerical methods differ. By appropriate choice of the trial function and the test function, we can obtain different numerical methods for solving the weak formulation of the problem. While typically in FEM the basis functions of the trial function and test function are identical, in FVM they are chosen differently. In this paper, we show which trial and test function must be chosen to derive the FVM alternatively: The trial function of the FVM is a "shifted" trial function of the FEM, where the nodal points are now located in the middle of an integration interval rather than at the ends. Moreover, the basis functions of the test function are no longer the same as those of the trial function as in the FEM, but are shown to be a constant equal to 1. This is demonstrated by the example of a 1D Poisson equation. Amsterdam Elsevier Ltd. 2022 Materials Today: Proceedings 62 2679 2683 10.1016/j.matpr.2022.05.460 2022-06-16 OPUS4-53422 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Völker, Daniel; Weisbrich, S.; Neitzel, F. Holl, H. The Finite Volume Method in point of view of Finite Element Method The best-known discretization methods for solving engineering problems formulated as partial differential equations are finite difference method (FDM), finite element method (FEM) and finite volume method (FVM). While the finite volume method is used in fluid mechanics, the finite element method is predominant in solid state mechanics. At first glance, FVM and FEM are two highly specialized methods. However, both methods can solve problems of both solid mechanics and fluid mechanics well. Since experimental mechanics deals not only with solid state physics but also with fluid mechanics problems, we want to understand FVM in the sense of FEM in this work. In the long term, we want to use the variational calculus to unify many important numerical methods in engineering science into a common framework. In this way, we expect that experiences can be better exchanged between different engineering sciences and thus innovations in the field of experimental mechanics can be advanced. But in this work, we limit ourselves to the understanding of the FVM with the help of the variational calculus already known in FEM. We use a simple 1D Poisson equation to clarify the point. First, we briefly summarize the FVM and FEM. Then we will deal with the actual topic of this paper, as we establish the FEM and the FVM on a common basis by variation formulation. It is shown here that the FVM can be understood in terms of the finite element method with the so-called Galerkin-Petrov approach. Johannes Kepler University 2021 Book of Abstracts 37th Danubia Adria Symposium on Advances in Experimental Mechanics 978-3-9504997-0-4 37th Danubia Adria Symposium on Advances in Experimental Mechanics Linz, Österreich 21.09.2021 24.09.2021 12 13 2021-09-30 OPUS4-53424 Posterpräsentation Wu, Cheng-Chieh The Finite Volume Method in point of view of Finite Element Method The best-known discretization methods for solving engineering problems formulated as partial differential equations are finite difference method (FDM), finite element method (FEM) and finite volume method (FVM). While the finite volume method is used in fluid mechanics, the finite element method is predominant in solid state mechanics. At first glance, FVM and FEM are two highly specialized methods. However, both methods can solve problems of both solid mechanics and fluid mechanics well. Since experimental mechanics deals not only with solid state physics but also with fluid mechanics problems, we want to understand FVM in the sense of FEM in this work. In the long term, we want to use the variational calculus to unify many important numerical methods in engineering science into a common framework. In this way, we expect that experiences can be better exchanged between different engineering sciences and thus innovations in the field of experimental mechanics can be advanced. But in this work, we limit ourselves to the understanding of the FVM with the help of the variational calculus already known in FEM. We use a simple 1D Poisson equation to clarify the point. First, we briefly summarize the FVM and FEM. Then we will deal with the actual topic of this paper, as we establish the FEM and the FVM on a common basis by variation formulation. It is shown here that the FVM can be understood in terms of the finite element method with the so-called Galerkin-Petrov approach. 2021 37th Danubia Adria Symposium on Advances in Experimental Mechanics Linz, Austria 21.09.2021 24.09.2021 2021-09-30 OPUS4-37529 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Aulova, Alexandra; Rogelj Ritonja, Alenka; Emri, Igor Approximate model for geometrical complex structures Many engineering structures are made of composite materials or metal foam. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. Ljubljana Narodna in univerzitetna knjižnica, Ljubljana 2016 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics - BOOK OF ABSTRACTS 978-961-94081-0-0 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics Portorož, Slovenia 20.09.2016 23.09.2016 52 53 2016-09-27 OPUS4-37521 Posterpräsentation Wu, Cheng-Chieh Determination of an approximate anisotropic model for a given geometrical complex isotropic structure by means of finite element method and least-squares adjustment Many engineering structures are made of composite materials or metal foam. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. 2016 PhD Day 2016 Berlin, Germany 01.09.2016 2016-09-27 OPUS4-37522 Vortrag Wu, Cheng-Chieh Ersatzmodell von komplexen geometrischen Strukturen für FEA Der Grad der Finite-Elemente-Diskretisierung wird vom Verhältnis der Details zur Objektgröße bestimmt. Die Diskretisierung eines großen Objektes mit vielen kleinen Details führt zu einer hohen Anzahl an Elementen bzw. Knotenpunkten. Die Berechnung solcher Körper erfordern nicht nur sehr hohe Rechenzeit, sondern was die Berechnung unmöglich macht, ist der sehr hohe Speicherbedarf. Mit Hilfe eines Ersatzkörpers wird dieses Problem umgangen. 2016 VDI/VDE-GMA Fachausschuss 2.12 "Strukturanalyse und -überwachung in der Bautechnik im Fachbereich Prozessmesstechnik und Strukturanalyse" Darmstadt, Germany 08.09.2016 2016-09-27 OPUS4-37523 Posterpräsentation Wu, Cheng-Chieh Approximate model for geometrical complex structures Many engineering structures are made of composite materials or metal foam. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. 2016 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics Portorož, Slovenia 20.09.2016 23.09.2016 2016-09-27 OPUS4-37524 Vortrag Wu, Cheng-Chieh Approximate model for geometrical complex structures Many engineering structures are made of composite materials or metal foam. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. 2016 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics Portorož, Slovenia 20.09.2016 23.09.2016 2016-09-27 OPUS4-31376 Vortrag Wu, Cheng-Chieh On optimal measurement set-ups for parameter identification from an integrated structural analysis of hybrid measurements and finite element model 2014 XIVth Bilateral Czech/German Symposium "Experimental Methods and Numerical Simulation in Engineering Science" XIVth Bilateral Czech/German Symposium "Experimental Methods and Numerical Simulation in Engineering Science" Wuppertal, Germany 2014-06-04 2014-06-07 2016-02-20 OPUS4-32044 Vortrag Wu, Cheng-Chieh Integrated structural analysis of hybrid measurement and finite element method for damage detection within a slender beam 2014 31st Danubia Adria Symposium on Advances in Experimental Mechanics 31st Danubia Adria Symposium on Advances in Experimental Mechanics Kempten, Germany 2014-09-24 2014-09-27 2016-02-20 OPUS4-32045 Vortrag Wu, Cheng-Chieh Advances in Structural Monitoring by an Integrated Analysis of Sensor Measurements and 3D Building Model 2014 9th International 3DGeoInfo 2014 9th International 3DGeoInfo 2014 Dubai, United Arab Emirates 2014-11-11 2014-11-13 2016-02-20 OPUS4-30913 Beitrag zu einem Tagungsband Weisbrich, S.; Wu, Cheng-Chieh; Neitzel, F. Harte, R. On optimal measurement set-ups for parameter identification from an integrated structural analysis of hybrid measurements and finite element model One major ambition in Structural Health Monitoring (SHM) is to develop the ability to detect, identify and localize damage as well as to predict the lifespan of civil structures (Worden et al. 2007). This would allow well-informed decision on whether to repair or to demolish these structures. The word monitoring in SHM brings up several frequently ignored questions: What type of sensors and accuracies are needed to monitor a given structure? Where are the optimal sensor placements? How many sensors are necessary? How to analyse spatially distributed hybrid measurements? Or, in short: What is the sensor configuration best suited for structural health monitoring? If these questions are not explicitly addressed, the usefulness of the measurement data for an evaluation is left to coincidence. Bergische Universität Wuppertal 2014 XIVth Bilateral Czech/German Symposium 'Experimental methods and numerical simulation in engineering science' XIVth Bilateral Czech/German Symposium 'Experimental methods and numerical simulation in engineering science' Wuppertal, Germany 04.06.2014 07.06.2014 46 47 2016-02-20 OPUS4-31540 Posterpräsentation Wu, Cheng-Chieh Integrated structural analysis of hybrid measurement and finite element method for damage detection within a slender beam 2014 31st Danubia Adria Symposium on Advances in Experimental Mechanics 31st Danubia Adria Symposium on Advances in Experimental Mechanics Kempten, Germany 2014-09-24 2014-09-27 2016-02-20 OPUS4-30619 Beitrag zu einem Tagungsband Becker, T.; Weisbrich, S.; Euteneuer, F.; Wu, Cheng-Chieh; Neitzel, F. Neue Möglichkeiten in der Bauwerksüberwachung durch integrierte Analyse von Sensormessungen und 3D-Bauwerksmodell Die Verwendung offener Standards bietet eine Vielzahl von Möglichkeiten, gerade im Bereich des Datenaustausches, Datenlagerung, aber auch der Interoperabilität. GML und CityGML sind hervorragende Beispiele für die Beschreibung von Realweltobjekten mittels eines offenen Standards wohingegen SensorML dazu dient, Messungen, Sensoren und Messplattformen zu beschreiben. Die Verwendung solcher Standards eröffnet dem Nutzer nicht nur die Möglichkeiten der Verwendung einer gemeinsamen standardisierten Sprache, sondern auch die Nutzung von offenen Servicestandards, wie Web Feature Service (WFS), Web Map Service (WMS) oder von Sensor Observation Services (SOS). Die Kombination von Geodaten- und Sensorstandards in einer Dienste- und Servicearchitektur geht über bisherige am Markt existierende Lösungen hinaus und schafft eine neuartige Plattform für die Bauwerksüberwachung, die weit mehr als ein simples Datenhaltungsmodell darstellt. Die in diesem Beitrag vorgestellte Plattform ermöglicht eine direkte Integration von Sensordaten sowie deren Bereitstellung durch eine offene Standardsprache. Dabei sind alle Zwischenschritte jederzeit über eine offene Diensteschnittstelle adressierbar und können so verschiedenen Akteuren zur Verfügung gestellt werden. Das große Potential und der Mehrwert eines derartigen Informationssystems liegt vor allem in der permanenten Verfüg-barkeit von Mess- und Objektdaten und einer damit verbundenen integrierten Analyse der Sensormessdaten in Kombination mit einem Finite-Elemente-Modell (FEM), basierend auf den Objektdaten. Die automatische Ableitung eines FE-Modells aus dem 3D-Bauwerks-modell, die Visualisierung der FEM-Simulationsergebnisse anhand des Bauwerksmodells, die Bereitstellung von Messrohdaten und Sensorinformationen zu jedem Messzeitpunkt machen die Plattform zu einem universell einsetzbaren Werkzeug im Bereich der Bauwerksüberwachung. In diesem Beitrag werden die einzelnen Bausteine, die verwendeten Standards und die Interaktion der einzelnen Komponenten zu einem Gesamtsystem vorgestellt. 2014 34. Wissenschaftlich-technische Jahrestagung der DGPF 23 34. Wissenschaftlich-technische Jahrestagung der DGPF Hamburg, Germany 26.03.2014 28.03.2014 Paper 254, 1 10 2016-02-20 OPUS4-31728 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Integrated structural analysis of hybrid measurement and finite element method for damage detection within a slender beam One major ambition in Structural Health Monitoring (SHM) is to develop the ability to detect, identify and localize damage as well as to predict the lifespan of civil structures. This would allow well-informed decision on whether to repair or to demolish these structures. We want to focus on the issues of detection and localisation of damage caused by material degradation within a slender beam - a structure that is often used as a construction carrier. Verein Deutscher Ingenieure (VDI) 2014 31st Danubia-Adria Symposium on advances in experimental mechanics (Proceedings) 978-3-00-046740-0 31st Danubia-Adria Symposium on advances in experimental mechanics Kempten, Germany 24.09.2014 27.09.2014 191 192 2016-02-20 OPUS4-34485 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Inverse finite element adjustment of material parameters from integrated analysis of displacement field measurement Zilina Faculty of Mechanical Engineering, Univerzity of Zilina, Slovakia 2015 32nd Danubia-Adria Symposium on advances in experimental mechanics (Proceedings) 978-80-554-1094-4 32nd Danubia-Adria Symposium on advances in experimental mechanics Starý Smokovec, Slovakia 2015-09-22 2015-09-25 78 79 2016-02-20 OPUS4-34333 Zeitschriftenartikel Abali, B. E.; Wu, Cheng-Chieh; Müller, W.H. An energy-based method to determine material constants in nonlinear rheology with applications Many polymer-type materials show a rate-dependent and nonlinear rheological behavior. Such a response may be modeled by using a series of spring-dashpot systems. However, in order to cover different time scales the number of systems may become unreasonably large. A more appropriate treatment based on continuum mechanics will be presented herein. This approach uses representation theorems for deriving material equations and allows for a systematic increase in modeling complexity. Moreover, we propose an approach based on energy to determine thematerial parameters.This method results in a simple linear regression problemeven for highly nonlinearmaterial equations. Therefore, the inverse problem leads to a unique solution. The significance of the proposed method is that the stored and dissipated energies necessary for the procedure are measurable quantities. We apply the proposed method to a 'semi-solid' material and measure its material parameters by using a simple-shear rheometer. Berlin Springer 2016 Continuum mechanics and thermodynamics 28 5 1221 1246 10.1007/s00161-015-0472-z 2016-02-20 OPUS4-34369 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Inverse finite element adjustment of material parameters from integrated analysis of displacement field measurement The integration of finite element method (FEM) into the least-squares adjustment presented in [1] is further extended for a joint evaluation of an elastostatic model and displacement field measurement. For linear solids which obey the HOOKE's law, the material parameters determination from measurements is being examined. In many literature, see for example [2], parameters are iteratively tuned until the computed FEM results are in accordance with the measurements. In contrast to these debatable approaches, we follow a rigorous and direct method. The "classical" FEM procedure starts with known material constants and ends up with computed fields such as dis-placement or temperature field. We present a method to invert the FEM procedure using the most general least-squares adjustment - the GAUSS-HELMERT Model (GHM). From given fields, the material parameters are directly calculated. 2015 32nd Danubia-Adria Symposium on Advances in Experimental Mechanics 32nd Danubia-Adria Symposium on Advances in Experimental Mechanics Stary Smokovec, Slovakia 22.09.2015 25.09.2015 2016-02-20 OPUS4-32736 Beitrag zu einem Sammelband Becker, T.; Weisbrich, S.; Wu, Cheng-Chieh; Neitzel, F. Breunig, M.; Al-Doori, M.; Butwilowski, E.; Kuper, P.V.; Benner, J.; Haefele, K.H. Advances in structural monitoring by an integrated analysis of sensor measurements and 3D building model The use of open GIS standards offers a broad variety of potential, particularly in the field of data exchange, data storage, and interoperability. GML and CityGML are excellent examples for the ontological description of real world objects by means of an open standard whereas SensorML serves to describe measurements, sensors and measuring platforms. The use of such standards offers not only the possibility of using a common standardised language, but also the use of open service standards. The combination of spatial data and sensor standards in services and service-oriented architectures goes far beyond previous existing solutions on the market and provides a novel platform for monitoring structures. That in fact is far more than a simple data storage model. The methods and models presented in this contribution allow a direct integration of sensor data and its provision through an open standard language. In this case, all the intermediate steps at any time through an open service interface are addressed and may be made available and provided to different actors and stakeholders participating in a construction scenario. The great potential and the added value of such an information system is the permanent availability of measurement and object data and an associated integrated analysis of sensor data in combination with a finite element model (FEM). The automatic derivation of a finite element model from the 3D structure model, the visualisation of FEM, the provision of raw (measurement) data and sensor information for each time of measurement transform the platform into a universal tool in the field of structural monitoring. This contribution introduces the individual components, the standards used and the interaction between the components to an overall system. Springer 2015 3D Geoinformation science - The selected papers of the 3D GeoInfo 2014 978-3-319-12180-2 141 156 10.1007/978-3-319-12181-9_9 2016-02-20 OPUS4-48053 Zeitschriftenartikel Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F.; Kadoke, Daniel; Fischer, Michael; Kohlhoff, Harald Pastramă, Ştefan Dan; Constantinescu, Dan Mihai A Small-Scale Test Bridge for Measurement and Model-based Structural Analysis The Measurement- and Model-based Structural Analysis (MeMoS) integrates a finite element model into least squares adjustment and thus allows to evaluate a mechanical model and measurements in a combined analysis. To examine the capability to detect and localise damage using this integrated analysis MeMoS, a small-scale truss bridge made of aluminium profiles is built as a test specimen for this purpose. Elsevier Ltd. 2019 Materials Today: Proceedings 12 35th Danubia Adria Symposium on Advances in Experimental Mechanics Sinaia, Romania 25.09.2018 28.09.2018 2 319 328 10.1016/j.matpr.2019.03.130 2019-05-27 OPUS4-48181 Zeitschriftenartikel Kowitz, Astrid; Wu, Cheng-Chieh; Helmerich, Rosemarie; Hille, Falk; Kadoke, Daniel; Gründer, Klaus-Peter; Hauser, S.; Schwarzinger, H. Bland, S. Impact on a micro-reinforced UHPC: Experimental studies versus numerical modeling Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. Amsterdam Elsevier Ltd 2019 Materials Today: Proceedings 12 2 474 483 10.1016/j.matpr.2019.03.152 2019-06-07 OPUS4-35648 Posterpräsentation Wu, Cheng-Chieh Inverse finite element adjustment of material parameters from integrated analysis of displacement field measurement The integration of finite element method (FEM) into the least-squares adjustment presented in is further extended for a joint evaluation of an elastostatic model and displacement field measurement. For linear solids which obey the Hooke's law, the material parameters determination from measurements is being examined. 2015 32nd Danubia-Adria Symposium on advances in experimental mechanics Starý Smokovec, Slovakia 22.09.2016 25.09.2016 2016-04-05 OPUS4-35629 Zeitschriftenartikel Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Nicoletto, G.; Pastrama, S. D.; Emri, I. Inverse finite element adjustment of material parameters from integrated analysis of displacement field measurement The determination of material parameters from displacement field measurement is being examined for linear elastic solid. A frequently used approach to compute material constants can be found in many studies. Even though they presented the approach in many different variations, but in the end they are essentially based on the same algorithm: Parameters are iteratively tuned until the computed results are in accordance with the measurements. The main drawback of this approach is that mainly commercial software is used that hinders us to investigate its inner evaluation process. This leads to the question, how the results from this commercial software can be trusted. On the contrary to these debatable approaches, we present a method that inverts the procedure of finite element method by using the most general model for a least-squares adjustment - the GAUSS-HELMERT Model. Elsevier Ltd. 2016 Materials Today: Proceedings 3 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics Starý Smokovec, Slovakia 22.09.2015 25.09.2015 4 1211 1215 10.1016/j.matpr.2016.03.004 2016-04-04 OPUS4-50197 Dissertation Wu, Cheng-Chieh The measurement- and model-based structural analysis for damage detection Die vorliegende Arbeit soll einen Beitrag zur Überwachung von Ingenieurbauwerken leisten. Die Detektion von Schäden an Bauwerken basiert auf der Auswertung von räumlich und zeitlich verteilten Hybridmessungen. Die erfassten Daten können rein geometrisch oder physikalisch ausgewertet werden. Letzteres ist vorzuziehen, da die Schadensursache mittels geometrisch-physikalischer Gesetze ermittelt werden kann, um rechtzeitig eingreifen und die weitere Nutzung der Bauwerke sicherstellen zu können. Aus diesem Grund werden die kontinuumsmechanischen Feldgleichungen in Verbindung mit der Finite-Elemente-Methode und Hybridmessungen durch die Ausgleichungsrechnung zu einer einzigen Auswertemethode kombiniert. Dabei ergeben sich zwei Aufgabenstellungen. Die erste Aufgabe beschäftigt sich mit der Beziehung zwischen der Finite-Elemente-Methode und der Ausgleichungsrechnung. Die Finite-Elemente-Methode löst bestimmte Problemklassen, die durch ein System elliptischer partieller Differentialgleichungen beschrieben werden. Während die Methode der kleinsten Quadrate eine weitere Klasse von Problemen löst, die als ein überdeterminiertes Gleichungssystem formuliert ist. Die auffallende Ähnlichkeit zwischen den beiden Methoden ist seit vielen Jahrzehnten bekannt. Es bleibt jedoch ungeklärt, warum diese Ähnlichkeit besteht. Der Beitrag soll dies klären, indem die Variationsrechnung im Hinblick auf ihr methodisches Vorgehen untersucht wird. Obwohl das bekannte Gauß-Markov-Modell innerhalb der Methode der kleinsten Quadrate und die Finite-Elemente-Methode inhärent unterschiedliche Problemklassen lösen, wird gezeigt, dass beide Methoden durch die gleichen methodischen Schritte der Variationsrechnung abgeleitet werden können. Aus methodischer Sicht bedeutet dies, dass beide Methoden nicht nur ähnlich, sondern sogar gleich sind. Außerdem wird darauf hingewiesen, wo eine mögliche Querverbindung zu anderen Methoden besteht. Die zweite Aufgabenstellung stellt eine Messungs- und Modellbasierte Strukturanalyse (MeMoS) durch die Integration der Finite-Elemente-Methode in die Ausgleichungsrechnung vor. In numerischen Untersuchungen wird gezeigt, wie diese integrierte Analyse zur Parameteridentifikation sowohl einfacher als auch beliebig geformter Strukturbauteile eingesetzt werden kann. Darauf aufbauend wird untersucht, mit welchen Beobachtungstypen, mit welcher Genauigkeit und an welcher Stelle der Struktur diese Messungen durchgeführt werden müssen, um die Materialparameter möglichst genau zu bestimmen. Dies dient der Ermittlung eines optimalen und wirtschaftlichen Messaufbaus. Mit dieser integrierten Analyse kann auch ein Ersatzmodell einer geometrisch komplexen Struktur ermittelt werden. Die Frage der Erkennung und Lokalisierung von Schäden innerhalb einer Struktur wird mit Hilfe dieser Strukturanalyse behandelt. Die Messungs- und Modellbasierte Strukturanalyse wird mit zwei verschiedenen Testaufbauten, einer Aluminium-Modellbrücke und einem Biegebalken, validiert. Berlin Bundesanstalt für Materialforschung und -prüfung (BAM) 2019 BAM-Dissertationsreihe 166 1 184 urn:nbn:de:kobv:b43-501977 https://creativecommons.org/licenses/by-nc-nd/4.0/deed.de 2020-01-22 OPUS4-49288 Dissertation Wu, Cheng-Chieh The measurement- and model-based structural analysis for damage detection The present work is intended to make a contribution to the monitoring of civil engineering structures. The detection of damage to structures is based on the evaluation of spatially and temporally distributed hybrid measurements. The acquired data can be evaluated purely geometrically or physically. It is preferable to do the latter, since the cause of damage can be determined by means of geometrical-physical laws in order to be able to intervene in time and ensure the further use of the structures. For this reason, the continuum mechanical field equations in conjunction with the finite element method and hybrid measurements are combined into a single evaluation method by the adjustment calculation. This results in two challenges. The first task deals with the relationship between the finite element method and the method of least squares. The finite element method solves certain problem classes, which are described by a system of elliptical partial differential equations. Whereas the method of least squares solves another class of problems, which is formulated as an overdetermined system of equations. The striking similarity between both methods is known since many decades. However, it remains unresolved why this resemblance exists. The contribution is to clarify this by examining the variational calculus, especially with regard to its methodological procedure. Although the well-known Gauss-Markov model within the method of least squares and the finite element method solve inherently different problem classes, it is shown that both methods can be derived by following the same methodological steps of the variational calculus. From a methodical viewpoint, this implies that both methods are not only similar, but actually the same. In addition, it is pointed out where a possible cross-connection to other methods exists. The second task introduces a Measurement- and Model-based Structural Analysis (MeMoS) by integrating the finite element method into the adjustment calculation. It is shown in numerical examinations how this integrated analysis can be used for parameter identification of simple as well as arbitrarily shaped structural components. Based on this, it is examined with which observation types, with which precision and at which location of the structure these measurements must be carried out in order to determine the material parameters as precisely as possible. This serves to determine an optimal and economic measurement set-up. With this integrated analysis, a substitute model of a geometrically complex structure can also be determined. The issue of the detection and localisation of damage within a structure is studied by means of this structural analysis. The Measurement and Model-based Structural Analysis is validated using two different test setups, an aluminum model bridge and a bending beam. Berlin Technische Universität Berlin 2019 1 169 urn:nbn:de:101:1-2019100201583156925935 10.14279/depositonce-8845 https://creativecommons.org/licenses/by-sa/4.0/deed.de 2019-10-16 OPUS4-49290 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Weisbrich, S.; Burger, M.; Neitzel, F. A Four-Point Bending Test Apparatus for Measurement- and Model-based Structural Analysis By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible. Pilsen, Czech Republic University of West Bohemia 2019 36th Danubia Adria Symposium on Advances in Experimental Mechanics EXTENDED ABSTRACTS 978-80-261-0876-4 36th Danubia Adria Symposium on Advances in Experimental Mechanics Pilsen, Czech Republic 24.09.2019 27.09.2019 63 64 2019-10-16 OPUS4-49291 Posterpräsentation Wu, Cheng-Chieh A Four-Point Bending Test Apparatus for Measurement- and Model-based Structural Analysis By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localize damage was examined. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localization responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed. In this attempt, the systematic influences such as residual stress are kept as low as possible. 2019 36th Danubia Adria Symposium on Advances in Experimental Mechanics Pilsen, Czech Republic 24.09.2019 27.09.2019 2019-10-16 OPUS4-48789 Posterpräsentation Bartholmai, Matthias; Johann, Sergej; Wu, Cheng-Chieh Airborne remote gas sensing and mapping Leaking methane (CH4) from infrastructures, such as pipelines and landfills, is critical for the environment but can also pose a safety risk. To enable a fast detection and localization of these kind of leaks, we developed a novel robotic platform for aerial remote gas sensing. Spectroscopic measurement methods for remote sensing of selected gases lend themselves for use on mini-copters, which offer a number of advantages for inspection and surveillance over traditional methods. No direct contact with the target gas is needed and thus the influence of the aerial platform on the measured gas plume can be kept to a minimum. This allows to overcome one of the major issues with gas-sensitive mini-copters. On the other hand, remote gas sensors, most prominently Tunable Diode Laser Absorption Spectroscopy (TDLAS) sensors have been too bulky given the payload and energy restrictions of mini-copters. Here, we present the Unmanned Aerial Vehicle for Remote Gas Sensing (UAV-REGAS), which combines a novel lightweight TDLAS sensor with a 3-axis aerial stabilization gimbal for aiming on a versatile hexacopter. The proposed system can be deployed in scenarios that cannot be addressed by currently available robots and thus constitutes a significant step forward for the field of Mobile Robot Olfaction (MRO). It enables tomographic reconstruction of gas plumes and a localization of gas sources. We also present first results showing its performance under realistic conditions. 2017 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures (SMAR 2019) Potsdam, Germany 27.08.2019 29.08.2019 2019-09-02 OPUS4-48790 Posterpräsentation Bartholmai, Matthias; Johann, Sergej; Wu, Cheng-Chieh KonSens - RFID embedded² systems in concrete - validation experiments Structural Health Monitoring (SHM) is an important part of buildings surveillance and maintenance to detect material failure as early as possible and to contribute in protection of structures and their users. The implementation of Radio Frequency Identification (RFID) sensor systems without cable connection and battery into building components offers innovative possibilities to enable long-term in-situ SHM of addressed structures, bridges. The objectives of the presented study are complete embedding of RFID sensors systems in concrete, full passive communication with the systems, at best for the whole life span of structures. One challenge for this task is the highly alkaline environment in concrete, which requires non-degrading and robust encapsulation. Further Requirements are passive communication and energy supply, appropriate antenna design, placement and fixation in concrete, and the selection and implementation of sensors and connections. The concept is to develop and optimize a simple and robust system, which meets the requirements, as well as comprehensive validation in concrete specimen and real world applications. Two different systems were developed (HF and UHF RFID, respectively). First tasks were the implementation of analog sensors using the superposition principle for the signal adaption. Investigation of suitable materials for robust encapsulation and sensor protection against basic environments. Four materials were investigated in pH 13 solution for 14 days - 3D-Printer-Polymer was completely resolved - PVC has no noticeable decrease in weight - (VitaPro) glass filter for the sensor protector, has weight loss 2.7 % - The epoxy resin has increased by 1.8 % due to moisture expansion Different concrete samples were prepared for the validation of the systems. RFID sensors were embedded in different integration depths. Investigate the energy- and data transfer through concrete, also with varying moisture content. Additionally, signal strength data was used to optimize and validate the antenna characteristics in concrete. Next steps are to guarantee a sufficient energy supply for UHF RFID systems embedded in different concrete mixtures and further embedding the HF and UHF RFID systems in real bridges and buildings to validate the long term monitoring. 2019 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures (SMAR 2019) Potsdam, Germany 27.08.2019 29.08.2019 2019-09-02 OPUS4-48791 Posterpräsentation Bartholmai, Matthias; Johann, Sergej; Wu, Cheng-Chieh 3D-Gestalts- und -Verformungsmessung - Anwendungsbeispiele Der Fokus des Arbeitsfelds ist die messtechnisch fundierte Anwendung der 3D-Verfahrenskombination zur Lösung vielfältiger Messaufgaben mit optimaler Datenqualität für interne und externe Kunden. Das setzt insbesondere eine jeweils problembezogene Messmethodik voraus. Dazu setzen wir kameragestützte 3D-Koordinatenmessverfahren ein, die auf dem fotogrammetrischen Prinzip der Bildtriangulation beruhen. Darunter fallen folgende miteinander flexibel kombinierbare Verfahrensmodifikationen: Mehrbildfotogrammetrie, Messadapter für Geometriemerkmale, Streifenprojektionsverfahren, statische bis hochdynamische Stereofotogrammetrie auf Punktebasis oder aufgabenangepasster Oberflächenmuster und mechanisch-optische Taster. 2019 5th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures (SMAR 2019) Potsdam, Germany 27.08.2019 29.08.2019 2019-09-02 OPUS4-51551 Zeitschriftenartikel Wu, Cheng-Chieh; Weisbrich, S.; Burger, M.; Neitzel, F. Zemčík, R. A four-point bending test apparatus for measurement- and model-based structural analysis By means of a small-scale truss bridge, the ability of the Measurement- and Model-based Structural Analysis to detect and localise damage was examined in. Although there was no noteworthy difficulty in detecting damage, it turned out that damage localisation responds sensitively to systematic influences, i.e. non-modelled properties of the mechanical model. Therefore, another experiment is being conducted to re-examine the Measurement- and Model-based Structural Analysis. For this purpose, the bending test is carried out as it has been already theoretically respectively numerically discussed in. In this attempt, the systematic influences such as residual stress are kept as low as possible. Elsevier Ltd. 2020 Materials Today: Proceedings 32 36th Danubia Adria Symposium on Advances in Experimental Mechanics Pilsen, Czech Republic 24.09.2019 27.09.2019 2 156 161 10.1016/j.matpr.2020.04.028 2020-11-16 OPUS4-47001 Beitrag zu einem Tagungsband Kowitz, Astrid; Wu, Cheng-Chieh; Hille, Falk; Helmerich, Rosemarie; Kadoke, Daniel; Gründer, Klaus-Peter; Hauser, S.; Schwarzinger, H. Pastramă, Ş. D.; Constantinescu, D. M. Impact on a micro-reinforced UHPC: Experimental studies versus numerical modeling Within the presented research project, experimental and numerical investigations were performed to develop a thin-shelled, modular, mobile element system made of a micro-reinforced ultra-high-performance ductile concrete (DUCON®). Material parameters were experimentally determined to adapt the material model within the numerical analysis applying the Drucker-Prager relationship. Afterwards, for validation of the numerical models, quasi-static and high-velocity impact tests were performed on plate-like structures. Finally, a suitable geometry of transportable barrier elements will be designed, which provides a maximum of resistance against impact by a minimum of weight and a maximum of mobility. Bucarest, Romania Editura Printech 2018 35th Danubia-Adria Symposium on Advances in Experimental Mechanics, Extended Abstracts 978-606-23-0874-2 35th Danubia-Adria Symposium on Advances in Experimental Mechanics Sinaia, Romania 25.09.2018 28. 09.2018 11 12 2018-12-13 OPUS4-42794 Zeitschriftenartikel Wu, Cheng-Chieh; Weisbrich, S.; Neitzel, F. Emri, Igor Approximate model for geometrical complex structures Many engineering structures are nowadays made of composite materials or metal foam. These modern engineering materials contain very complex inner geometry. To simulate the deformational behaviour of these structures often requires a high number of discretisation elements. This in turn yields a very large system of linear equations that are extremely time and memory consuming or practically impossible to solve. It is therefore desirable to find an approach to overcome this obstacle. In this paper a numerical method is proposed to find an approximate substitute model for geometrical complex structures. Amsterdam, Netherlands Elsevier 2017 Materials Today: Proceedings 4 33rd Danubia Adria Symposium on Advances in Experimental Mechanics Portorož, Slovenia 20.09.2016 23.09.2016 5, Part 1 5995 6000 10.1016/j.matpr.2017.06.084 2017-11-09 OPUS4-46113 Posterpräsentation Wu, Cheng-Chieh A small-scale test bridge for measurement- and model-based structural analysis To examine the capability to detect and localise damage using the Measurement- and Model-based Structural Analysis (MeMoS), a small-scale truss bridge (1520 mm × 720 mm × 720 mm) made of aluminium profiles is built as a test specimen for this purpose. The truss frame of the test bridge is made of aluminium profiles with a sophisticated design of the cross-sectional area. In comparison, with solid profiles, only a fraction of the material is needed to produce the profiles, while their bending resistance decreases slightly. The profiles are built into a truss frame by connecting them by means of fastening sets made of steel. The bridge model is mounted on four steel bearings which each of them consist of a cylinder arranged between two plates. Fixed bearings are made by holding onto one end of the bridge. The bridge is subjected by an external load by placing a heavy object beneath it. At the same time, measurements can be conducted below the bridge. Therefore, the bridge specimen is elevated by attaching it on a pedestal with four columns. Damages can be induced by loosening the fastening pieces. 2018 35th Danubia-Adria Symposium on Advances in Experimental Mechanics Sinaia, Romania 25.09.2018 28.09.2018 2018-10-02 OPUS4-46116 Beitrag zu einem Tagungsband Wu, Cheng-Chieh; Kadoke, Daniel; Fischer, Michael; Kohlhoff, Harald; Weisbrich, S.; Neitzel, F. Pastramă, Ştefan Dan; Constantinescu, Dan Mihai A small-scale test bridge for measurement- and model-based structural analysis To examine the capability to detect and localise damage using the Measurement- and Model-based Structural Analysis (MeMoS), a small-scale truss bridge (1520 mm × 720 mm × 720 mm) made of aluminium profiles is built as a test specimen for this purpose. The truss frame of the test bridge is made of aluminium profiles with a sophisticated design of the cross-sectional area. In comparison, with solid profiles, only a fraction of the material is needed to produce the profiles, while their bending resistance decreases slightly. The profiles are built into a truss frame by connecting them by means of fastening sets made of steel. The bridge model is mounted on four steel bearings which each of them consist of a cylinder arranged between two plates. Fixed bearings are made by holding onto one end of the bridge. The bridge is subjected by an external load by placing a heavy object beneath it. At the same time, measurements can be conducted below the bridge. Therefore, the bridge specimen is elevated by attaching it on a pedestal with four columns. Damages can be induced by loosening the fastening pieces. Bukarest PRINTECH 2018 35TH DANUBIA ADRIA SYMPOSIUM ON ADVANCES IN EXPERIMENTAL MECHANICS Extended abstracts 978-606-23-0874-2 35th Danubia-Adria Symposium on Advances in Experimental Mechanics Sinaia, Romania 25.09.2018 28.09.2018 23 24 2018-10-02