TY - CONF A1 - Beck, Uwe A1 - Mitzkus, Anja A1 - Sahre, Mario A1 - Weise, Matthias A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Basedau, Frank A1 - Hofmann, Detlef A1 - Schukar, Vivien T1 - Faser-basierter magneto-optischer Schicht-Sensor zum Monitoring von Bauteilen N2 - In Glasfasern eingeschriebene Bragg-Gitter (FBG: fibre-based Bragg gratings) sind über die Verschiebung der Bragg-Wellenlänge in der Lage, Stauchungen und Dehnungen von Glasfasern hochgenau zu erfassen. In Kompositwerkstoffe eingebettete faseroptische Sensoren können Bauteile bezüglich ihrer mechanischen Integrität überwachen und früh-zeitig Informationen über Materialveränderungen gewinnen. Um die Zuverlässigkeit eines solchen Sensors zu gewährleisten, ist es wichtig, die korrekte Funktion des Sensors im Verbund mit der Werkstoff-Matrix on-line und in-situ sicherzu-stellen. Im Rahmen des DFG-Projekts FAMOS² (FAser-basierter Magneto-Optischer SchichtSensor) wurde ein selbstdiagnosefähiger Schichtsensor entwickelt, der mit Hilfe von magnetostriktiven Aktorschichten aus Nickel bzw. Eisen-Nickel validiert werden kann. Der FAMOS²-Schichtsensor wird durch ein PVD (physical vapour deposition)/ECD (electro-chemical deposition) Hybridschichtsystem realisiert, das auf dem Fasermantel im Bereich des FBG haftfest, homogen und langzeitfunktional abzuscheiden ist. Dabei wird in einem ersten Schritt ein etwa 100 Nanometer dünnes PVD-Schichtsystem aus Chrom und Kupfer als Haftvermittler auf der Glasfaser bzw. als leitfähige Startschicht für den nachfolgenden ECD-Prozess abgeschieden. Um eine rotationssymmetrische Schich-tabscheidung zu gewährleisten, erfolgt während der PVD-Beschichtung eine Rotation der Glasfasern. In einem zweiten Schritt wird dann unter Verwendung eines klassischen Watts-Elektrolyten in einer speziell entwickelten ebenfalls rotationssymmetrisch aufgebau-ten ECD-Durchströmungszelle dann die etwa 30 Mikrometer dicke, magnetostriktive Ak-torschicht auf dem PVD-Schichtsystem abgeschieden, im Vergleich sowohl reine Nickel-Schichten als auch Nickel-Eisen-Schichten. Ein äußeres Magnetfeld dehnt die magnetostriktive Aktorschicht und damit auch die Faser reversibel. Diese Dehnung führt zu einer Verschiebung der Bragg-Wellenlänge, welche direkt mit der Stärke eines zu messenden oder zu Validierungszwecken vorgegebenen Magnetfeldes korreliert. Die Anpassung der Beschichtungsverfahren an die Fasergeome-trie und die mechanischen Eigenschaften der Hybridschichten werden hinsichtlich der me-chanischen Integrität des faseroptischen Sensors diskutiert und der Nachweis der Selbst-diagnosefähigkeit erbracht. T2 - 13. ThGOT Thementage Grenz- und Oberflächentechnik und 11. Thüringer Biomaterial-Kolloquium CY - Zeulenroda, Germany DA - 13.03.2018 KW - Magneto-optischer Sensor KW - Faser-Bragg Gitter KW - Magnetostriktive Beschichtung KW - Selbstkalibrierung KW - Bauteilmonitoring PY - 2018 SN - 978-3-00-058187-8 SP - 1 EP - 5 CY - Jena AN - OPUS4-44599 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Mitzkus, Anja A1 - Gong, Xin A1 - Sahre, Mario A1 - Bartholmai, Matthias A1 - Beck, Uwe ED - Emri, Igor T1 - A contribution to intelligent automatic validation of structure-integrated fibre optic strain sensors N2 - An auto-validation tool for the reliability quantification of materials integrated fiber Bragg grating (FBG) strain sensors have been developed and tested. The FBG strain sensor was jacketed with a magnetostrictive layer based on iron-nickel which, when excited by a specific magnetic field, adds an artificial strain to the sensor. The fixed relationship between magnetic induction and wavelength shift of the FBG strain sensor characterizes the bond strength and adhesion between the sensor and the surrounding structure. Due to an easily applicable magnetic field, it is possible to validate the sensor performance in a non-contact, fast way without disturbing the data-acquisition process. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Fiber Bragg grating KW - Self-diagnosis KW - Magnetostriction KW - Strain KW - Auto-validation PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308489 DO - https://doi.org/10.1016/j.matpr.2017.06.073 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5935 EP - 5939 PB - Elsevier Ltd. AN - OPUS4-41583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Moldenhauer, Laura A1 - Helmerich, Rosemarie A1 - Köppe, Enrico A1 - Haamkens, Frank A1 - Wittmann, Jochen ED - Emri, Igor T1 - Experimental feasibility study about moisture in building materials measured with Bluetooth N2 - Structural health monitoring contributes to early damage detection in the built infrastructure. During the last two decades, sensor networks transferred from wired to wireless sensor networks. Several methods exist to measure moisture in building materials. Most of the introduced commercial moisture measurement methods provide information about the local or near surface moisture. A feasibility study is presented to demonstrate, how the Received Signal Strength Indicator (RSSI) of a Bluetooth Low Energy (BLE) signal, transmitted from the BLE-module embedded in building materials, correlate with changing moisture content. The feasibility of this influence was investigated in the presented study. The maximum and minimum RSSI were systematically recorded and analysed. T2 - 33nd Danubia Adria Symposium on Advances in Experimental Mechanics CY - Portoroz, Slovenia DA - 20.09.2016 KW - BLE KW - Long-Term Monitoring KW - Network KW - Structural Health Monitoring KW - Moisture Measurement KW - RSSI KW - Bluetooth Low Energy KW - Sensor PY - 2017 UR - http://www.sciencedirect.com/science/article/pii/S2214785317308398 DO - https://doi.org/10.1016/j.matpr.2017.06.053 SN - 2214-7853 VL - 4 IS - 5, Part 1 SP - 5889 EP - 5892 PB - Elsevier Ltd. AN - OPUS4-41585 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Daum, Werner A1 - Gong, Xing A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Schukar, Vivien A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe T1 - New self - diagnostic fiber optical sensor technique for structural health monitoring N2 - Fiber optic sensors have gained increasing importance in recent years and are well established in many areas of industrial applications. In this paper, we introduce a concept of a self-diagnostic fiber optic sensor. The presented sensor is to resolve the problems of embedded fiber optic sensors in complex structures and to enable the validation under operational conditions. For this purpose, different magnetostrictive coated fiber optic sensors were developed and various experiments were performed to verify their mode of Operation and to determine the respective reproducibility. The measuring principle is illustrated by obtained experimental results, which showed a change in wavelength from 1 pm at a magnetic field strength change of 0.25 mT. In addition, the temperature characteristics of the implemented magnetostrictive sensor were analyzed and an experimental factor of 1.5 compared to a reference fiber optic sensor was determined. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Self-diagnostic fiber optical sensor KW - Magnetostrictive metal coating KW - Magnetic field KW - Fiber bragg grating PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.038 SN - 2214-7853 VL - 3 IS - 4 SP - 1009 EP - 1013 AN - OPUS4-37131 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Schukar, Vivien A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Gong, Xin A1 - Basedau, Frank A1 - Bartholmai, Matthias A1 - Beck, Uwe T1 - Magnetic field detection with an advanced FBG-based sensor device N2 - A high-performance fiber Bragg grating-based (FBG) sensor device for the detection of small magnetic fields has been developed. Based on a smart multilayer coating exposed over the physical length of the FBG, magnetic fields exhibited by rotating machine parts, power generators or current cable can easily be detected, analysed and evaluated. Consequently, this innovative, in-process and non-contact inspection method leads to an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical concept is based on a magnetostrictive multilayer coating system that strains the high-resolution FBG element. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element forms the characteristic sensitivity curve. Intensive tests regarding the characterisation of the magnetic field FBG sensor have been carried out and its performance has been evaluated. T2 - EuroSensors XXX 2016 CY - Budapest, Hungary DA - 04.09.2016 KW - Strain KW - Fiber Bragg grating KW - Magnetostriction KW - Magnetic field PY - 2016 AN - OPUS4-37364 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Gaal, Mate A1 - Bartusch, Jürgen A1 - Schadow, Florian A1 - Köppe, Enrico A1 - Dohse, Elmar ED - Chimenti, D. E. ED - Bond, L. J. T1 - Focusing of ferroelectret air-coupled ultrasound transducers N2 - Air-coupled ultrasound has been applied increasingly as a non-destructive testing method for lightweight construction in recent years. It is particularly appropriate for composite materials being used in automotive and aviation industry. Air-coupled ultrasound transducers mostly consist of piezoelectric materials and matching layers. However, their fabrication is challenging and their signal-to-noise ratio often not sufficient for many testing requirements. To enhance the efficiency, air-coupled ultrasound transducers made of cellular polypropylene have been developed. Because of its small density and sound velocity, this piezoelectric ferroelectret matches the small acoustic impedance of air much better than matching layers applied in conventional transducers. In our contribution, we present two different methods of spherical focusing of ferroelectret transducers for the further enhancement of their performance in NDT applications. Measurements on carbon-fiber-reinforced polymer (CFRP) samples and on metal adhesive joints performed with commercially available focused air-coupled ultrasound transducers are compared to measurements executed with self-developed focused ferroelectret transducers. T2 - 42nd Annual Review of Progress in Quantitative Nondestructive Evaluation CY - Minneapolis, Minnesota, USA DA - 26.07.2015 KW - Ferroelectret KW - Transducer KW - Air-coupled KW - Ultrasonic KW - Focusing PY - 2016 SP - 080001 PB - AIP Publishing CY - Melville, NY, USA AN - OPUS4-35955 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Gong, Xin A1 - Bartholmai, Matthias A1 - Beck, Uwe T1 - Magnetic field detection with an advanced FBG-based sensor device N2 - A high-performance fiber Bragg grating-based (FBG) sensor device has been developed for the detection of small magnetic fields. Based on a smart multilayer jacket around the fibre over the physical length of the FBG, magnetic fields generated by rotating machine parts, power generators or power cable can be easily detected, analysed and evaluated. Consequently, this innovative, on-line and non-contact inspection method results in an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical principle is based on a magnetostrictive multilayer system that strains the high-resolution FBG element in presence of magnetic fields. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element describes the characteristic sensitivity curve. Intensive tests regarding characterisation of this magnetic field FBG sensor have been carried out and its performance has been evaluated. T2 - 30th Eurosensors Conference, EUROSENSORS 2016 CY - Budapest, Hungary DA - 04.09.2016 KW - Fiber Bragg grating KW - Magnetostriction KW - Strain KW - Magnetic field PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-376703 DO - https://doi.org/10.1016/j.proeng.2016.11.445 SN - 1877-7058 VL - 168 SP - 1270 EP - 1274 PB - Elsevier Ltd. AN - OPUS4-37670 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe A1 - Gong, Xing A1 - Bartholmai, Matthias ED - Aulova, Alexandra ED - Rogelj Ritonja, A. ED - Emri, I. T1 - A contribution to intelligent automatic validation of structure-integrated fibre optic strain sensors N2 - Sensors integrated into devices and structures provide essential data to control, optimize or manage machines and structural components. In the last years, processes, applications and machine parts became more and more intelligent. Consequently, the need for sensor validation increased significantly in order to rely on sensor data and measurement results. Structure-integrated fibre optic strain sensors, such as fiber Bragg gratings (FBG), are of special interest in the composite manufacturing industry. This type of sensor makes it possible to gain information and to collect measurement data about entire production processes and whole life-time cycles of composite-made machine parts and structures. However, validation concepts and approaches for this type of sensors are barely reported in literature. Furthermore, all the reported activities have the drawback that the sensor diagnosis strategy is implemented as limited mathematical models and/or complex time-consuming spectral analysis tools which are applied in data post-processing loops. However, to automate sensor validation and to apply real-time and in-field sensor fault detection, it is necessary to acquire measurement data and information about the measurement reliability at the same time. T2 - 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Fiber bragg grating KW - Magnetic field KW - Magnetostrictive metal coating KW - Self-diagnostic fiber optical sensor PY - 2016 SN - 978-961-94081-0-0 SP - 180 EP - 181 CY - Ljubljana AN - OPUS4-37645 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Köppe, Enrico A1 - Moldenhauer, Laura A1 - Haamkens, Frank A1 - Helmerich, Rosemarie T1 - Feuchtemessung in Bauteilen und anderen Strukturen mit Bluetooth Low Energy N2 - Die Langzeitüberwachung von Bauteilen (Structural Health Monitoring, SHM) ging in den letzten Jahren zunehmend von verkabelten Sensoren zu kabellosen Sensornetzwerken (WSN) über. Frühwarnsysteme sollen rechtzeitige Signale senden, wenn Schädigungsprozesse einsetzen, wenn ein Bauteil z. B. zu feucht wird (Deiche, Staumauern), oder wenn Feuchteprozesse in Bauteilen auftreten, die den Transport von schädlichen Stoffen ermöglichen. Mittels handelsüblicher multifunktionaler Sensoren wie einem Bluetooth Low Energy (BLE) wurden erste Machbarkeitsuntersuchungen zur Massenfeuchtemessung durchgeführt. Die untersuchten Parameter sind der sogenannte Received Signal Strength Indicator (RSSI) eines Bluetooth-Low-Energy(BLE)-Signals und die abgestrahlte Sendeleistung eines eingebetteten BLE-Moduls. Das BLE-Modul kommuniziert mit einem mobilen smarten Empfänger wie einem Tablet oder einem Smartphone als SmartHub. Die Veränderung des RSS-Indikators ist ein Maß für die Veränderung der Feuchte im Bauteil, während die ausgesandte Signalstärke konstant bleibt. Wenn das BLE-Signal einen feuchten Bereich im Baumaterial durchläuft, verändert sich der RSS-Indikator. Nach erfolgreicher Machbarkeitsstudie wurde nun ein aus dem Netzwerk MI4G (Modern Industry for Germany) zwischen der Bundesanstalt für Materialprüfung und dem Klein- und mittelständigen Unternehmen LinTech GmbH heraus beantragtes ZIM-Projekt bewilligt. Der Bericht zeigt erste Ergebnisse von Voruntersuchungen und gibt einen Ausblick auf weitere Forschungsaktivitäten. KW - Bluetooth KW - BLE KW - Feuchtemessung KW - Bauteil KW - Bluetooth Low Energy PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/bate.201600074/epdf DO - https://doi.org/10.1002/bate.201600074 SN - 0932-8351 A 1556 VL - 93 IS - 10 SP - 747 EP - 751 PB - Ernst & Sohn CY - Deutschland AN - OPUS4-38163 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Moldenhauer, Laura A1 - Helmerich, Rosemarie A1 - Köppe, Enrico A1 - Haamkens, Frank A1 - Wittmann, Jochen ED - Aulova, Alexandra ED - Rogelj Ritonja, Alenka ED - Emri, Igor T1 - Experimental feasibility study about moisture in building materials measured with bluetooth N2 - Structural health monitoring contributes to early damage detection in the built infrastructure. During the last two decades, the sensor networks transferred from wired to wireless sensor networks. Several methods exist to measure moisture in building materials. Most of the introduced commercial humidity measurement methods as provide information about the local or near surface moisture. A feasibility study is presented to demonstrate, how the Received Signal Strength Indicator (RSSI) of a BlueTooth® Low Energy (BLE) signal, transmitted from the BLE-module embedded in building materials with changing moisture content. The BLE-module communicates with a mobile Smart Device as tablet or mobile phone. The RSSI indicates to what extend the received signal strength is changed due to moisture, while the transmitted signal strength remains constant. T2 - The 33rd Danubia Adria Symposium on Advances in experimental mechanics CY - Portoroz, Slovenia DA - 20.09.2016 KW - Bluetooth KW - Moisture KW - Measurement KW - Water dipoles KW - RSSI PY - 2016 SN - 978-961-94081-0-0 SP - 60 EP - 61 PB - SSEM--Slovene Society of Experimental Mechanics CY - Ljubljana, Slovenia AN - OPUS4-38086 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Richter, Frank A1 - Köppe, Enrico A1 - Daum, Werner T1 - Tracking deformation history in split Hopkinson pressure bar testing N2 - The stress vs. strain curve of materials is affected the rate of imposed straining. Among the methods for dynamic testing the technique known as 'split Hopkinson pressure bar' (SHPB) has evolved into the most widely used one to exert high-speed straining. The theory behind it comprises simple equations to compute stress and strain. The reliability of the strain analysis can be assessed by digital image correlation (DIC). The present results indicate that the visually observed strain is smaller than predicted by theory. T2 - 32nd Danubia-Adria Symposium on advances in experimental mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Digitale Bildkorrelation (DIC) KW - Dynamische Tests KW - Spannungs-Dehnungs-Kurve KW - Digital image correlation (DIC) KW - Dynamic testing KW - Split Hopkinson pressure bar (SHPB) KW - Stress-strain curve PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.017 SN - 2214-7853 VL - 3 IS - 4 SP - 1139 EP - 1143 PB - Elsevier CY - Oxford AN - OPUS4-34487 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schukar, Vivien A1 - Gong, Xin A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe ED - Berghmans, F. ED - Mignani, A. G. T1 - Modelling and simulation of a fibre Bragg grating strain sensor based on a magnetostrictive actuator principle N2 - A new concept for the self-diagnosis of embedded fiber Bragg grating (FBG) strain sensors was developed, simulated and experimentally tested. This concept is based on a magnetostrictive metallic layer directly coated on the fibre cladding over the grating segment of the FBG sensor, so that an on-demand external magnetic field in a millitesla scale can produce a controllable artificial strain as an indication signal for the remote optical interrogator. The relationship between the pre-defined magnetic field and its induced Bragg wavelength shift characterizes this validation concept. Any deviation of the local bonding state of the interfaces from the initial or/and any change of shear strain transferring mechanism from composite matrix to the optical fibre core will result in alterations in this sensitive relationship, and thus triggers an immediate alert for a further inspection. The finite element method is used to simulate the strain of this configuration as result of different values of the magnetic field in order to optimize the geometrical sensor parameters. The simulations are verified by experiments results. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only. T2 - Optical Sensing and Detection IV CY - Brüssel, Belgium DA - 03.04.2016 KW - Fiber Bragg gratings KW - Actuators KW - Modeling and simulation KW - Finite element methods PY - 2016 SN - 9781510601444 DO - https://doi.org/10.1117/12.2224728 SN - 0277-786X SN - 1996-756X VL - 9899 SP - 9899-39 PB - SPIE Digital Library AN - OPUS4-38634 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Mitzkus, Anja A1 - Sahre, Mario A1 - Reinstädt, Philipp A1 - Griepentrog, Michael A1 - Beck, Uwe A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Basedau, Frank A1 - Hofmann, Detlef A1 - Gong, Xin A1 - Schukar, Vivien T1 - Altbekannter Watts-Elektrolyt, junge Hightech-Anwendung, Nickel- und Nickel-Eisen-Schichten als magnetostriktive Aktorschicht auf faseroptischen Sensoren N2 - Durch faseroptische Sensoren können Bauteile im Einsatz kontinuierlich überwacht und frühzeitig Informationen über Materialveränderungen gewonnen werden. Mittels einer magnetostriktiven Aktorschicht, welche den Sensor umhüllt, kann nun auch die korrekte Sensorfunktion jederzeit kontrolliert werden. Als Aktorschicht eignet sich galvanisch abgeschiedenes reines Nickel oder Nickel-Eisen in der Zusammensetzung 50:50. Um diese haftfest mit dem Sensor zu verbinden wurde ein ECD/PVD-Kombinationsschichtsystem entwickelt. Die mechanischen Eigenschaften der ECD-Schicht können sowohl mit einer auf die Fasergeometrie angepassten instrumentierten Eindringprüfung als auch einem 2-Punkt-Biegeversuch bestimmt werden. KW - Faseroptik-Sensoren KW - ECD-Aktorschicht KW - PVD-Haftfestigkeit KW - Nickel-/Nickel-Eisen- Magnetostriktion PY - 2016 SN - 2195-5891 SN - 2195-5905 VL - 12 SP - 1 EP - 4 AN - OPUS4-39129 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schadow, Florian A1 - Gaal, Mate A1 - Bartusch, Jürgen A1 - Dohse, E. A1 - Köppe, Enrico T1 - Focusing air-coupled ultrasonic transducers based on ferroelectrets N2 - Rising importance of composite lightweight structures in aircraft and automobile industries increases the demand on reliable non-destructive testing methods for these structures. Air-coupled ultrasonic testing emerged to suit these requirements as it does not require any liquid coupling medium. In conventional air-coupled ultrasonic transducers, matching layers are used in order to decrease the impedance mismatch between transducer and air. Matching layers can be omitted by using ferroelectrets, which are charged cellular polymers having ferroelectric and piezoelectric properties. Especially a low Young’s modulus, low density and low sound velocity of cellular polypropylene (cPP) are properties being required for well-matched air-coupled ultrasonic transducers. In our contribution we show recent enhancements of cPP transducers resulting in focused sound fields and thus improved lateral sensitivity. The influence of different transmitter apertures was evaluated using measurements of the emitted sound field. Further we show a transmission of a test specimen of carbon-fiber-reinforced plastic (CFRP) containing artificial damages. Results of focused transducers were compared to planar ferroelectret transducers, as well as to conventional air-coupled transducers. T2 - 19th World Conference on Non-Destructive Testing 2016 CY - München, Germany DA - 13.06.2016 KW - Air-coupled ultrasonic testing KW - Ferroelectrets KW - Cellular polypropylene KW - Focused sound fields KW - Focused transducers PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-355116 UR - http://www.ndt.net/search/docs.php3?showForm=off&id=19453 SP - 1 EP - 8 AN - OPUS4-35511 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Richter, Frank A1 - Köppe, Enrico A1 - Daum, Werner T1 - Tracking deformation history in split Hopkinson pressure bar testing N2 - The stress vs. strain curve of materials is affected the rate of imposed straining. Among the methods for dynamic testing the technique known as 'split Hopkinson pressure bar' (SHPB) has evolved into the most widely used one to exert high-speed straining. The theory behind it comprises simple equations to compute stress and strain. The reliability of the strain analysis can be assessed by digital image correlation (DIC). The present results indicate that the visually observed strain is smaller than predicted by theory. T2 - 32nd Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Split Hopkinson pressure bar (SHPB) KW - Digital image correlation (DIC) KW - Digitale Bildkorrelation (DIC) KW - Dynamic testing KW - Dynamische Tests KW - Stress-strain curve KW - Spannungs-Dehnungs-Kurve PY - 2015 SN - 978-80-554-1094-4 SP - 174 EP - 175 PB - University of Zilina, Slovakia CY - Zilina AN - OPUS4-35656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Bartholmai, Matthias A1 - Daum, Werner A1 - Gong, Xin A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Schukar, Vivien A1 - Westphal, Anja A1 - Sahre, Mario A1 - Beck, Uwe T1 - New self diagnostic fiber optical sensor technique for structural health monitoring N2 - Fiber optic sensors have gained increasing importance in recent years and are well established in many areas of industrial applications. In this paper, we introduce a concept of a self-diagnostic fiber optic sensor. The presented sensor is to resolve the problems of embedded fiber optic sensors in complex structures and to enable the validation under operational conditions. For this purpose, different magnetostrictive coated fiber optic sensors were developed and various experiments were performed to verify their mode of operation and to determine the respective reproducibility. The measuring principle is illustrated by obtained experimental results, which showed a change in wavelength from 1 pm at a magnetic field strength change of 0.25 mT. In addition, the temperature characteristics of the implemented magnetostrictive sensor were analyzed and an experimental factor of 1.5 compared to a reference fiber optic sensor was determined. T2 - 32nd Danubia-Adria Symposium on advances in experimental mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 PY - 2015 SN - 978-80-554-1094-4 SP - 1 EP - 2 CY - Zilina AN - OPUS4-35173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Subaric-Leitis, Andreas A1 - Köppe, Tabea T1 - Auswertung der Messunsicherheit eines Multisensorsystems zur Wege- und Positionsbestimmung sich bewegender Objekte in Gebäuden T2 - VDI/VDE-Mess- und Automatisierungstechnik, Messunsicherheit praxisgerecht bestimmen, Prüfprozesse in der industriellen Praxis CY - Braunschweig, Germany DA - 2015-11-19 PY - 2015 AN - OPUS4-35032 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Subaric-Leitis, Andreas A1 - Wilk, Tabea T1 - Auswertung der Messunsicherheit eines Multisensorsystems zur Weg- und Positionsbestimmung sich bewegender Objekte in Gebäuden N2 - In den letzten Jahren ist die Bestimmung der Position eines sich bewegenden Objektes eine immer interessanter werdende Information geworden. Die aktuelle Position oder der zurückgelegte Weg wird mittels miniaturisierter integrierter 3D-Sensoren bestimmt. Durch die Integration dieser Sensoren in moderne Smartphones oder in spezielle robuste Hardware sind die Anwendungsgebiete vielseitig. Die ermittelte Position innerhalb von Gebäuden ist dabei für den Kaufmann innerhalb eines Shoppingcenters aber auch für den Feuerwehrmann im Einsatz wichtig. Für den Kaufmann bedeutet es durch gezielte Angebote potenzielle Kunden anzusprechen und damit seinen Umsatz zu steigern. Für den Einsatzleiter der Feuerwehr ist die genaue Position seiner Feuerwehrmänner im Einsatz lebensrettend und bietet damit eine zusätzliche Sicherheit für die Einsatzkraft. Das hier vorgestellte Multisensorsystem, allgemein als Inertialsystem bezeichnet, und das darauf angewendete Verfahren zur Positionsbestimmung wird in diesem Bericht vorgestellt und näher beschrieben. Die systematischen und zufälligen Messunsicherheitsbeiträge des Inertialsystems und deren Auswirkungen auf die Bestimmung der aktuellen Position und somit auf den resultierenden zurückgelegten Weg werden erörtert. T2 - 7. VDI-Fachtagung Messunsicherheit 2015 - Messunsicherheit praxisgerecht bestimmen - Prüfprozesse in der industriellen Praxis CY - Braunschweig, Germany DA - 19.11.2015 PY - 2015 SN - 978-3-18-092269-0 SN - 0083-5560 N1 - Serientitel: VDI-Berichte – Series title: VDI-Berichte IS - 2269 SP - 173 EP - 181 PB - VDI-Verl. AN - OPUS4-35118 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Edel, M. A1 - Köppe, Enrico T1 - An advanced method for pedestrian dead reckoning using BLSTM-RNNs N2 - Location estimation and navigation, especially on smartphones has shown great progress in the past decade due to its low cost and ability to work without additional infrastructure. However, a challenge is the positioning, both in terms of step detection, step length approximation as well as heading estimation, which must be accurate and robust, even when the use of the device is varied in terms of placement or orientation. In this paper, we propose a scheme for retrieving relevant information to detect steps and to estimate the correct step length from raw inertial measurement unit (IMU) data. This approach uses Bidirectional Long Short-Term Memory Recurrent Neural Networks (BLSTM-RNNs). Designed to take contextual information into account, the network can process data gathered from different positions, resulting in a system, which is invariant with respect to transformation and distortions of the input patterns. An experimental evaluation on a dataset produced from 10 individuals demonstrates that this new approach achieves significant improvements over previous attempts and increase the current state-of-the-art results even in the presence of variations and degradations. We achieved a mean classification rate of 98.5% and a standard deviation of 0.70 for 10000 different test sequences and an average error of 1.45% regarding the step length. Thus is the best result on the task gathered in the experiments compared with competing techniques. T2 - IPIN 2015 - 6th International conference on indoor positioning and indoor navigation CY - Banff, Alberta, Canada DA - 13.10.2015 KW - Indoor positioning KW - Inertial tracking KW - Dead reckoning KW - Deep learning KW - Machine learning PY - 2015 SN - 978-1-4673-8402-5 DO - https://doi.org/10.1109/IPIN.2015.7346954 SN - 2162-7347 SP - Paper 1570149259, 1 EP - 6 AN - OPUS4-35119 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Enrico A1 - Hofmann, Detlef A1 - Daum, Werner T1 - Absolut messendes EFPI-Messsystem T2 - 17. ITG-/GMA-Fachtagung Sensoren und Messsysteme 2014 CY - Vienna, Austria DA - 2014-06-03 PY - 2014 AN - OPUS4-31533 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -