TY - JOUR A1 - Lebid, S. A1 - Habel, Wolfgang A1 - Daum, Werner T1 - How to reliably measure composite-embedded fibre Bragg grating sensors influenced by transverse and point-wise deformations? N2 - Embedded conventional fibre Bragg grating (FBG) sensors with acrylate coating have been chosen for monitoring novel textile-reinforced composite materials with a complicated wavy structure as a result of reinforcing textures. Problems of monitoring this type of material occur due to the harsh fabrication technology of the composite and its complicated structure. Embedded fibre sensors are exposed to the influence of transverse and point-wise deformations. To what extent will these effects influence the measurement signal of a sensor? Temperature cycles, tension and vibration tests were carried out to answer this question. Transverse and point-wise deformation and micromechanical indentation tests on non-embedded FBG sensors were carried out to clarify the reliability of recorded signals. KW - FBG sensors KW - Textile-reinforced composites KW - Measurement reliability PY - 2004 UR - http://www.iop.org/EJ/abstract/0957-0233/15/8/001/ U6 - https://doi.org/10.1088/0957-0233/15/8/001 SN - 0957-0233 SN - 1361-6501 VL - 15 SP - 1441 EP - 1447 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-3846 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krebber, Katerina A1 - Lenke, Philipp A1 - Liehr, Sascha A1 - Nöther, N. A1 - Wendt, Mario A1 - Wosniok, Aleksander A1 - Daum, Werner T1 - Structural health monitoring by distributed fiber optic sensors embedded into technical textiles N2 - Technical textiles with embedded distributed fiber optic sensors have been developed for the purposes of structural health monitoring in geotechnical and civil engineering. The distributed fiber optic sensors are based on Brillouin scattering in silica optical fibers and OTDR in polymer optical fibers. Such 'smart' technical textiles are used for reinforcement of geotechnical and masonry structures. The embedded fiber optic sensors provide online information about the condition of the structure and about the occurrence and location of any damage or degradation.-------------------------------------------------------------------------------------------------------------------------------------------------------- Technische Textilien mit integrierten faseroptischen Sensoren eröffnen neue Möglichkeiten der Zustandsüberwachung (structural health monitoring) in Geotechnik und Ingenieurbau. Die verteilt messenden Sensoren basieren auf der Brillouin-Streuung in Glasfasern und auf der OTDR in polymeroptischen Fasern. Derartige 'intelligente' technische Textilien werden in erster Line zur Verstärkung von geotechnischen Bauwerken und von Gebäuden genutzt. Die integrierten Sensoren liefern eine zeitnahe Information über den bestimmungsgemäßen Zustand des Bauwerks sowie über die Entstehung und den Ort von lokalen Bauwerksschäden. KW - Fiber optic sensor KW - Distributed sensor KW - Brillouin scattering KW - Polymer optical fiber KW - Strain sensor KW - Smart geotextiles KW - Faseroptischer Sensor KW - Verteilter Sensor KW - Brillouin-Streuung KW - Polymeroptische Faser KW - Dehnungssensor KW - Intelligentes Geotextil PY - 2012 U6 - https://doi.org/10.1524/teme.2012.0238 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 79 IS - 7-8 SP - 337 EP - 347 PB - Oldenbourg CY - München AN - OPUS4-26387 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Appajaiah, Anilkumar A1 - Wachtendorf, Volker A1 - Daum, Werner T1 - Characterization of thermo-oxidative stability of polymer optical fibers using chemiluminescence technique N2 - The thermo-oxidative stability of commercially available polymer optical fibers (POFs) and their components (cores and claddings) was investigated. All the bare POFs (core and cladding only) studied here were based on poly(methyl methacrylate) (PMMA) core. The fibers were exposed to 100 °C/low humidity for about 4200 h. Chemiluminescence (CL) technique was applied to investigate the thermo-oxidative stability and for measuring the transmission loss during exposure a prototype device called multiplexer was used. POFs exhibited variation in thermo-oxidative stability although they possessed identical core material PMMA. This was due to difference in the chemical compositions of claddings. Claddings were more susceptible to the thermo-oxidative degradation compared to cores. The thermo-oxidative degradation of both the cladding and the core was found in POFs as a result of climatic exposure. POFs showed an early drop-off followed by a slow decline of transmission. The early drop-off of transmission was attributed to physical changes like thermal expansion and the slow decline of transmission to chemical changes like oxidative degradation of POFs. A good linear relationship between optical transmission stability and thermo-oxidative stability of POFs was established from these studies. KW - Polymer optical fibers (POFs) KW - Chemiluminescence (CL) KW - Thermo-oxidative stability KW - Aging KW - Optical transmission stability PY - 2006 U6 - https://doi.org/10.1016/j.polymdegradstab.2006.05.006 SN - 0141-3910 SN - 1873-2321 VL - 91 IS - 11 SP - 2605 EP - 2613 PB - Applied Science Publ. CY - London AN - OPUS4-13984 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Köppe, Tabea A1 - Bartholmai, Matthias A1 - Daum, Werner ED - Ognjanovic, M. ED - Stankovic, M. ED - Ristic, M. T1 - Introduction in the system of the split Hopkinson pressure bar and validation of the method N2 - The Split Hopkinson Pressure Bar (SHPB) or Kolsky Bar is known as a method for analysing mechanical properties of a material under dynamic load. Referring to the name it is a splitted Hopkinson Pressure Bar. The Hopkinson Bar is related to its inventor Bertram Hopkinson (1914). He used it to analyze stone samples under dynamic load. Later his construction was improved by Davies (1948) [1] and Kolsky (1949) [2], who had the idea to split the bar and put a sample in between. The technique is used to measure a lot of different mechanical properties of a material e.g. the dynamic Young’s modulus, deformation behaviour or to chart the dynamic stress-strain diagram. Further applications are the measurement of the elastic wave and the analysis of the propagation of the wave [2]. In the last years there was still an interest in measuring dynamic properties with a SHPB. Nevertheless no comprehensive validation of the system exists. Another problem is that the stress and the strain in the sample are only calculated with simplified estimations. The aim of this paper is to give a first impression of important points validating the system. On account of different setups of the SHPB a validation of the used system is necessary. Hence it is important to look at the theory. Further in this paper the measurement results will be shown in a strain over time diagram. T2 - DAS-29 - 29th Danubia-Adria-symposium on advances in experimental mechanics CY - Belgrade, Serbia DA - 2012-09-26 PY - 2012 SN - 978-86-7083-762-1 N1 - Geburtsname von Köppe, Tabea: Wilk, T. - Birth name of Köppe, Tabea: Wilk, T. SP - 52 EP - 53 CY - Belgrade, Serbia AN - OPUS4-26638 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Daum, Werner A1 - Gründer, Klaus-Peter A1 - Kadoke, Daniel A1 - Protz, Christian A1 - Zencker, Uwe T1 - Optical 3D dynamic deformation analysis of a ram container during a drop test T2 - 30th Danubia-Adria symposium on advances in experimental mechanics CY - Primosten, Croatia DA - 2013-09-25 KW - Steel sheet container KW - Drop test KW - Numerical simulation KW - Optical digitization KW - High speed stereo photogrammetry PY - 2013 SN - 978-953-7539-17-7 SP - 45 EP - 46 AN - OPUS4-29414 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 U6 - 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 - JOUR A1 - Habel, Wolfgang R. A1 - Krebber, Katerina A1 - Daum, Werner T1 - Results in standardization of FOS to support the use of SHM systems N2 - Measurement and data recording systems are important parts of a holistic Structural Health Monitoring (SHM) system. New sensor technologies such as fiber-optic sensors are often used; however, standards (or at least guidelines) are not yet available or internationally approved. This lack in standardization makes the acceptance of FOS technologies in complex SHM systems substantially difficult. A standard family for different FOS technologies is therefore being developed that should help to design SHM systems in an optimal way. International standardization activities take place in several standardization bodies such as IEC and ASTM, and within SHM societies such as ISHMII. The paper reports on activities in standardization of fiber-optic sensors, on results already achieved, and on newly started projects. Combined activities of fiber sensor experts and SHM experts from Civil Engineering are presented. These contributions should help owners of structures as well as developers of sensors and monitoring systems to select effective and validated sensing technologies. Using these standards, both parties find recommendations how to proceed in development of SHM systems to evaluate the structural behavior based on e.g. standardized fiber optic sensors, and to derive necessary measures, e.g. the optimal maintenance strategy. T2 - Sixth European Workshop on Optical Fibre Sensors CY - Limerick, Ireland DA - 30.05.2016 KW - Fiber-optic sensor KW - Standard KW - Temperature KW - Strain KW - Monitoring KW - Structural health KW - Application PY - 2016 U6 - https://doi.org/10.1117/12.2236863 SN - 0277-786X VL - 9916 SP - 991625-1 EP - 991625-4 AN - OPUS4-37053 LA - eng 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 - TY - CONF A1 - Köppe, Tabea A1 - Daum, Werner T1 - Pulse shaping and alignment tests with the split Hopkinson pressure bar for validation N2 - The Split Hopkinson Pressure Bar (SHPB) is a method for material characterization which works at strain rates from 102 - 104 1/s. This method can be used for example in the field of military engineering, in the field of deformation technology, automobile indurstry, aerospace industry or in other industrial fields. Controlled tests with the SHPB device enable Information about the dynamic material deformaion behaviour in the named strain rate area. The setup of the SHPB is not standarized and the measurement principle is dependent on simplifications. Due to this amongst others the problem with the dispersion of the measurement signal occurs. Furthermore it is possible that measurement uncertainties appear caused by the misalignment of the SHPB setup. In this work the influence of the alignment and a dispersion correction by pulse shaping is presented. On the one side for the alignment calibration tests are done. And on the other side for the dispersion influence correction with pulse shaping tests are done with TiA16V4. This material was choosen due to the fact that it can be compared with existing literature data. 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 - 242 EP - 243 AN - OPUS4-31730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -