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 OPUS4-29852 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 OPUS4-50197 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 OPUS4-53422 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 OPUS4-31376 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 OPUS4-30913 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 OPUS4-30619 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 OPUS4-48790 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 OPUS4-34369 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