TY - CONF A1 - Brandes, K. A1 - Kubowitz, P. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Basedau, Frank T1 - Lagrange Multiplikator-Test zur Detektierung von zunehmender Strukturschädigung N2 - Mit einem auf Lagrange-Multipiikator-Tests basierenden Monitoring von Brücken ist es gelungen, in Belastungsversuchen an einer Holzbrücke (7,25 m Spannweite), an der relativ kleine Schädigungen künstlich herbeigeführt worden waren, die Zuverlässigkeit dieser Art des Monitorings zu bestätigen. Ausgangspunkte waren Messung von Durchbiegungen sowie Krümmungen und die Zusammenführung der jeweiligen Regression mit Nebenbedingungen, die den mechanischen Bedingungen gehorchen, unter Einschluss von Lagrange-Multiplikatoren, die sich als brauchbare Testparameter erwiesen. T2 - 8. Symposium Experimentelle Untersuchungen von Baukonstruktionen CY - Dresden, Germany DA - 24.09.2015 KW - Schadensfrüherkennung KW - Strukturschädigung KW - Monitoring PY - 2015 SN - 1613-6934 N1 - Serientitel: Schriftenreihe Konstruktiver Ingenieurbau Dresden – Series title: Schriftenreihe Konstruktiver Ingenieurbau Dresden IS - 40 SP - 147 EP - 157 CY - Dresden AN - OPUS4-34793 LA - deu 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 - Daum, Werner A1 - Rose, Peter T1 - Automatische Isolierung von Schweissnahtfehlern in Röntgenaufnahmen aus der zerstörungsfreien Materialprüfung T2 - 1. Internationale Fachtagung Automatische Bildverarbeitung CY - Berlin, Germany DA - 1985-10-17 PY - 1985 SP - 1 EP - 4 PB - Kammer der Technik CY - Berlin AN - OPUS4-34202 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Heidt, Heinrich A1 - Rose, Peter A1 - Raabe, P. A1 - Daum, Werner T1 - Digital image processing for radiography in nuclear power plants T2 - 7th International Conference on NDE in the nuclear industry CY - Grenoble, France DA - 1985-01-28 PY - 1985 SP - 317 EP - 319 CY - Grenoble AN - OPUS4-34215 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 - Bartholmai, Matthias A1 - Werner, Klaus-Dieter A1 - Kohlhoff, Harald A1 - Helmerich, Rosemarie A1 - Daum, Werner ED - Aulova, Alexandra ED - Rogelj Ritonja, A. ED - Emri, I. T1 - Long-Term measurement of vertical displacements at the outer concrete bridges of the Berlin Main Station N2 - Berlin Main Station is the largest multi-level station in Europe. Its daily passenger number amounts to over 300.000. Structures built for such a large number of people require a high-level safety standard. The station was built on the inner city site of the historic Lehrter Bahnhof. The conditions for building and start of operation were challenging by several reasons. The typical sandy ground with a high level of groundwater makes the permanent static stability of such a complex structure difficult. Several completed, ongoing, and planned construction activities in the immediate vicinity of the station influence the ground settlement of the whole area. On basis of the structural design an impact prediction was calculated, which expected certain vertical displacements particularly between the single columns of the outer concrete bridges of the building. These columns support the glass roof construction, which only allows a defined limit of displacement. In order to avoid damage, a concept for monitoring and adjusting potentially occurring displacements was developed for installation at the outer bridges of the station. T2 - 33rd Danubia- Adria Symposium on Advances in Experimental Mechanics CY - Portorož, Slovenia DA - 20.09.2016 KW - Berlin Main Station KW - Differential displacements KW - Hydraulic levelling system KW - Laser-based displacement measuring system KW - Monitoring KW - Strain measurements PY - 2016 SN - 978-961-94081-0-0 SP - 166 EP - 167 CY - Ljubljana AN - OPUS4-37646 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bartholmai, Matthias A1 - Werner, Klaus-Dieter A1 - Johann, Sergej A1 - Daum, Werner ED - Cosmi, F. T1 - Characterization of the temperature behavior of a piezoresistive accelerometer N2 - Piezoresistive accelerometers use a strain-sensing element, generally made of semiconductor material, e.g., silicon to convert the mechanical motion into an electrical signal. This element is usually designed in form of a cantilever beam loaded with a mass. Acceleration causes bending of the beam, which produces a change of electrical resistance proportional to the applied acceleration. Main advantages of piezoresistive accelerometers in comparison to other types, e.g., piezoelectric and capacitive, is their robust and highly dynamic behavior, which qualifies them for application in high impact shock applications. Mechanical damping is typically implemented with silicon oil in a way that the output signal is undistorted over a wide frequency range. These characteristics principally qualify them for the application in drop tests carried out at BAM, for which they are calibrated over the frequency range from 1 to 4 kHz. However, using silicon oil for damping, has the drawback of temperature dependent change of its viscosity, leading to temperature dependent deviation of the accelerometer’s sensitivity. This study presents experimental results of the temperature behavior of a piezoresistive accelerometer with a dynamic range up to ±5000 g. This type of accelerometer is applied for drop tests which are partially performed at temperatures of -40 or +100 °C. T2 - 34th Danubia-Adria Symposium on Advances in Experimental Mechanics CY - Trieste, Italy DA - 19.09.2017 KW - Accelerometer KW - Temperature behavior KW - Drop test PY - 2017 UR - https://www.openstarts.units.it/handle/10077/14921 SN - 978-88-8303-863-1 SP - 93 EP - 95 CY - Trieste AN - OPUS4-42109 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 N2 - In diesem Paper wird ein absolut messendes faseroptisches Messsystem zur Bestimmung des Gap-Abstandes von niedrig reflektierenden losen und festen extrinsischer Fabry-Pérot Interferometer (EFPI) vorgestellt. Die häufigste Methode zur Bestimmung von Dehnungen oder Bewegungen durch EFPI-Sensoren ist eine kontinuierliche relative Ermittlung einer Veränderung mit einer nachträglichen Auswertung. Unterbrechungen in der Datenerfassung oder Fehler bei der Interferenzstreifen-Auswertung führen zu einer nicht abschätzbaren Messunsicherheit. Damit war es bis dato nicht möglich, eine absolute Veränderung von eingesetzten EFPI-Sensoren zu bestimmen. Mit dem an der BAM entwickelten Verfahren, ist dies jetzt möglich, die absolute Veränderung zu bestimmen. Dieses System namens 'EFPI-Scan' wird in dem Papier dargestellt werden. T2 - Sensoren und Messsysteme 2014 - 17. ITG/GMA-Fachtagung CY - Nürnberg, Germany DA - 03.06.2014 PY - 2014 SN - 978-3-8007-3622-5 SN - 0932-6022 N1 - Serientitel: ITG-Fachbericht – Series title: ITG-Fachbericht VL - 250 SP - P16.2, 1 EP - 3 PB - VDE Verlag GmbH AN - OPUS4-32644 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Brandes, K. A1 - Daum, Werner A1 - Hofmann, Detlef A1 - Kubowitz, P. T1 - Lagrange multiplier test for structural damage of bridges N2 - Detecting spreading damage in bridges is a demanding task for engineers today when the ageing infrastracture of industriaiized countries is degradating more and more. To successfully deal with tbis problem, a really advanced method has been elaborated basing on Langrange Multiplier (LM) tests and following the principle of simplicity by Hilbert and extending comments by Helmholtz refering to a combination of measurement and analytical treatment. Finally, an easy mathematical fonnation has been created. T2 - 31st Danubia-Adria Symposium on advances in experimental mechanics CY - Kempten, Germany DA - 24.09.2014 PY - 2014 SN - 978-3-00-046740-0 SP - 213 EP - 214 AN - OPUS4-31725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Klunker, André A1 - Köppe, Tabea A1 - Daum, Werner T1 - Different numerical methods around the SHPB experiment N2 - The Split Hopkinson Pressure Bar (SHPB) is a materials testing apparatus primarily designed for the analysis of viscoplastic material behavior at very high strain rates. Because of its complexity it is common practice to simplify the underlying exact mechanical theory by making strong assumptions. On the one hand this has to be done to achieve any results at all on the other hand one commits systematic errors. Therefore we utilize different numerical and Simulation methods to analyze and minimize these errors. T2 - 31st Danubia-Adria Symposium on advances in experimental mechanics CY - Kempten, Germany DA - 24.09.2014 PY - 2014 SN - 978-3-00-046740-0 N1 - Geburtsname von Köppe, Tabea: Wilk, T. - Birth name of Köppe, Tabea: Wilk, T. SP - 189 EP - 190 AN - OPUS4-31726 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -