TY - JOUR A1 - Bartelmeß, Jürgen A1 - Zimmek, David A1 - Bartholmai, Matthias A1 - Strangfeld, Christoph A1 - Schäferling, M. T1 - Fibre optic ratiometric fluorescence pH sensor for monitoring corrosion in concrete N2 - In this communication a novel concept for pH sensing is introduced which is specifically adapted to monitor carbonation induced corrosion in concrete structures. The method is based on a ratiometric measurement principle, exploiting the pH sensitive colour switching of thymol blue in the basic pH regime and the emissive properties of two different (Zn)CdSe/ZnS core shell quantum dots. The transition point of thymol blue in a Hydrogel D4 matrix was determined to be at around pH 11.6, which fits ideally to the intended application. Next to the fundamental spectroscopic characterization of the ratiometric response, a new design for a sensor head, suitable for the incorporation into concrete matrices is presented. Toward this, a manufacturing process was developed which includes the preparation of a double layer of polymers containing either thymol blue or a quantum dot mixture inside a porous ceramic tube. Results of a proof-of-priciple performance test of the sensor head in solutions of different pH and in cement specimens are presented, with encouraging results paving the way for future field tests in concrete. KW - Fiber optic sensing KW - PH monitoring in concrete KW - Embedded sensors KW - Ratiometric fluorescence PY - 2020 DO - https://doi.org/10.1039/c9an02348h VL - 145 IS - 6 SP - 2111 EP - 2117 PB - Royal Society of Chemistry AN - OPUS4-50381 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bartholmai, Matthias A1 - Johann, Sergej A1 - Kammermeier, Michael A1 - Müller, Maximilian A1 - Strangfeld, Christoph T1 - Transmission characteristics of RFID sensor systems embedded in concrete N2 - Completely embedded sensor systems for long-term operation offer innovative possibilities for structural health monitoring of concrete structures. Measuring of relevant parameters, e.g., temperature, humidity, or indication of corrosion can be performed with low energy sensors. This allows to implement passive RFID sensor systems without cable connection and battery, which are power supplied exclusively by the electromagnetic field from the external reader device. To evaluate characteristics and conditions of this concept, a systematical investigation of the transmission characteristics with variation of relevant parameters, as communication frequency, installation depth, type of concrete, moisture content, etc. is currently carried out in an interdisciplinary research project at BAM. First results are presented in this paper. T2 - IEEE Sensors 2016 CY - Orlando, FL, USA DA - 30.10.2016 KW - Embedded sensors KW - Energy harvesting KW - Wireless sensors KW - RFID sensors KW - Transmission characteristics KW - Structural health monitoring PY - 2016 SN - 978-1-4799-8287-5 SN - 1930-0395 SP - 1541 EP - 1543 PB - IEEE AN - OPUS4-38388 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Kammermeier, Michael A1 - Koeppe, Tabea A1 - Werner, Klaus-Dieter ED - Nicoletto, G. ED - Pastrama, S.D. ED - Emri, I. T1 - High dynamic measurement of strain and acceleration using a multichannel measuring system with single cable serial connection N2 - Strain and acceleration measurement during high dynamic drop tests, e.g., of containments for dangerous goods is performed using high speed multichannel measuring systems. So far established and operated systems need a cable connection of every strain gauge and acceleration sensor with the measuring device, often counting up to a number of more than 100 cables, corresponding to the number of applied sensors. The result is a massive cable harness consisting of all single cables, which is difficult to handle and causes a number of practical problems. An innovative approach is proposed by using a single cable measuring system, consisting of measuring modules with data bus connection and local data acquisition. Promising results were presented in a previous study. This paper follows up with additional results from full-scale testing of a further enhanced single cable system for the application in drop tests. T2 - 32nd DANUBIA ADRIA SYMPOSIUM on Advances in Experimental Mechanics CY - Starý Smokovec, Slovakia DA - 22.09.2015 KW - Multichannel measuring KW - Single cable serial connection KW - Dangerous goods container KW - Drop test KW - High impact testing PY - 2016 DO - https://doi.org/10.1016/j.matpr.2016.03.023 SN - 2214-7853 VL - 3 IS - 4 SP - 931 EP - 935 PB - Elsevier Ltd. AN - OPUS4-35689 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Kammermeier, Michael A1 - Werner, Klaus-Dieter A1 - Köppe, Tabea T1 - Single cable, multichannel measuring system for heavy load, high impact drop tests N2 - Multichannel measuring systems are used to measure strains and accelerations during drop tests of containments for dangerous goods. Conventional systems require cabling of each sensor and co-falling of the cable harness, causing problems in the test preparation and execution. Promising results of a single cable measuring system, consisting of measuring modules with data bus connection and local data acquisition were presented in a previous study. This paper follows up with results from laboratory and full-scale testing of an further enhanced single cable system for the application in drop tests.---------------------------------------------------------------------------------------------------------------------------------------------------------------- Vielkanalmesssysteme werden zur Messung von Dehnungen und Beschleunigungen bei Fallversuchen von Gefahrstoffbehältern eingesetzt. Konventionelle Systeme erfordern die Verkabelung jeder einzelnen Messstelle und somit das Mitfallen eines Kabelbaums, wodurch Probleme bei der Versuchsvorbereitung und Durchführung entstehen. In einer vorangegangenen Studie wurden vielversprechende Ergebnisse durch Verwendung eines 1-Kabelmesssystems mit Datenbus und dezentraler Datenspeicherung erzielt. Dieser Artikel beinhaltet weiterführende Ergebnisse aus Labor- und Realversuchen mit einem weiterentwickelten System zur Anwendung bei Fallversuchen. KW - Multichannel measuring system KW - Single cable measuring KW - Dangerous goods container KW - Drop test KW - High Impact testing KW - Hopkinson bar KW - Vielkanalmesssystem KW - Gefahrstoffe KW - Behälter KW - Fallprüfung KW - Hochdynamische Prüfung KW - Hopkinsonstab PY - 2013 DO - https://doi.org/10.1524/teme.2013.0033 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 N1 - Geburtsname von Köppe, Tabea: Wilk, T. - Birth name of Köppe, Tabea: Wilk, T. VL - 80 IS - 7-8 SP - 249 EP - 255 PB - Oldenbourg CY - München AN - OPUS4-28963 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bartholmai, Matthias A1 - Köppe, Enrico A1 - Prager, Jens ED - Boller, C. T1 - Early damage detection of structural defects using guided waves N2 - Limited access to the object of relevance is often an essential problem in testing routines, e.g. for non-destructive testing of industry facilities or components of means of transportation. The presented project is about the development of a non-destructive testing method for application over great distances (up to 100 m). The method is based on directed excitation and measuring of Lamb waves (guided waves). It enables an effective differentiation of structural and defective indications as well as a classification of different defect types. The advantage of guided waves is the ability of propagation over great distances. This offers innovative possibilities for the investigation of large or difficult to access constructions. The testing method can be helpful in a broad variety of applications. It is useable for the characterization of plane or cylindrical, thin-walled surfaces of metal or fiber laminated materials. Particularly the investigation of aircraft wings and other aerospace components as well as the investigation of pipelines are addressed fields of application. T2 - EWSHM'12 - 6th European workshop on structural health monitoring 2012 CY - Dresden, Germany DA - 03.07.2012 KW - Lamb-waves KW - Ultrasound KW - Non-destructive evaluation KW - Early-damage-detection KW - Structural health monitoring PY - 2012 SN - 978-3-940283-41-2 VL - 2 SP - 1471 EP - 1478 CY - Berlin AN - OPUS4-26240 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Neumann, Patrick P. T1 - Adaptive ortsaufgelöste Gaskonzentrationsmessung mit einer Mikrodrohne KW - Gasmessung KW - Gasemission KW - Emissionskontrolle KW - Windvektor KW - Mikrodrohne KW - Data-Mapping KW - Gas measurement KW - Gas emission KW - Emission control KW - Wind vector KW - Micro-drone KW - Data mapping PY - 2011 DO - https://doi.org/10.1524/teme.2011.0158 SN - 0340-837X SN - 0178-2312 SN - 0171-8096 VL - 78 IS - 10 SP - 470 EP - 478 PB - Oldenbourg CY - München AN - OPUS4-24652 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Neumann, Patrick P. A1 - Lazik, D. T1 - Multifunctional sensor for monitoring of CO2 underground storage by comprehensive and spatially resolved measuring of gas concentrations, temperature and structural changes N2 - One of the main unsolved issues of CCS is the comprehensive surveillance of CO2 storage areas with reasonable effort and costs. This study presents an approach for distributed subsurface monitoring of gas storage areas. The concept combines different measurement technologies to one multifunctional sensor: membrane based measurement technology for in situ monitoring of gases in soil and fibre optical sensing of temperature and strain (as a measure for structural change). A test field of application-relevant dimensions is built up to validate and optimize the technology. T2 - GHGT 11 - Greenhouse gas control technologies conference CY - Kyoto, Japan DA - 2012-11-18 KW - Multifunctional sensor KW - Distributed sensor KW - Monitoring of CO2 KW - Subsurface monitoring KW - Gas storage areas KW - Membrane-based gas sensing KW - Fibre optical sensing PY - 2013 UR - http://reginnovations.org/key-scientific-articles/multifunctional-sensor-monitoring-co2-underground-storage-comprehensive-spatially-resolved-measuring-gas-concentrations-temperature-structural-changes/ DO - https://doi.org/10.1016/j.egypro.2013.06.303 SN - 1876-6102 VL - 37 SP - 4033 EP - 4040 PB - Elsevier CY - Amsterdam AN - OPUS4-28910 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Bartholmai, Matthias A1 - Neumann, Patrick P. A1 - Werner, Klaus-Dieter A1 - Ebert, Sebastian A1 - Lazik, D. T1 - Linear sensor for areal subsurface gas monitoring - calibration routine and validation experiments N2 - Membrane based linear gas sensors and fiber optical sensors feature similar geometries and complement each other in quantities to be measured. To the author's best knowledge, it is the first time that these sensors are combined to a multifunctional sensor for distributed measuring of gas concentrations, temperature, and strain. Objective is a comprehensive monitoring of underground gas storage areas. In the presented project a 400 m² test site and a corresponding laboratory system were just built up to characterize, validate, and optimize the combined sensor. Application of the sensor lines in a grid structure should enable spatial resolution of the measurement data and early detection of relevant events, as gas leakage, temperature change, or mechanical impact. A Calibration routine was developed which can be applied subsequent to underground installation. First measurement results indicate the potential of the method, with regard to highly topical energy transport and storage issues. T2 - IEEE Sensors 2014 conference CY - Valencia, Spain DA - 02.11.2014 KW - Linear sensor KW - Distributed sensor KW - Monitoring of CO2 KW - Subsurface monitoring KW - Gas storage areas KW - Membrane-based gas sensing KW - Fibre optical sensing PY - 2014 SN - 978-1-4799-0161-6 DO - https://doi.org/10.1109/ICSENS.2014.6985157 SP - 942 EP - 945 AN - OPUS4-32083 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Schartel, Bernhard T1 - Layered silicate polymer nanocomposites: new approach or illusion for fire retardancy? Investigations of the potentials and the tasks using a model system N2 - Polymeric nanocomposites are discussed as one of the most promising advanced materials whose nanoscale effects can be exploited for industry. Layered silicate polypropylene-graft-maleic anhydride nanocomposites are investigated as a model to clarify the potential of such materials in terms of fire retardancy. The nanostructure is characterized using transmission electron microscopy (TEM) and shear viscosity. The fire behavior is characterized using different external heat fluxes in cone calorimeter, limiting oxygen index and UL 94 classification. A comprehensive fire behavior characterization is presented which enables an assessment of the materials’ potential with respect to different fire scenarios and fire tests. The influence of morphology and the active mechanisms are discussed, such as barrier formation and changed melt viscosity. To our knowledge, it is the first attempt to illuminate the concept’s strengths, such as the reduction of flame spread, and weaknesses, such as the lack of influence on ignitability, in a clear, comprehensive and detailed manner. KW - Fire retardancy KW - Nanocomposites KW - Cone Calorimeter KW - LOI KW - UL94 KW - Flame retardance KW - poly(propylene) (PP) KW - Organoclay PY - 2004 UR - http://www3.interscience.wiley.com/cgi-bin/jissue/109085890 SN - 1042-7147 SN - 1099-1581 VL - 15 IS - 7 SP - 355 EP - 364 PB - John Wiley & Sons, Ltd. CY - Chichester AN - OPUS4-3706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Bartholmai, Matthias A1 - Schartel, Bernhard T1 - Assessing the performance of intumescent coatings using bench-scaled cone calorimeter and finite difference simulations N2 - A method was developed to assess the heat insulation performance of intumescent coatings. The method consists of temperature measurements using the bench-scaled experimental set-up of a cone calorimeter and finite difference simulation to calculate the effective thermal conductivity dependent on time/temperature. This simulation procedure was also adapted to the small scale test furnace, in which the standard time-temperature curve is applied to a larger sample and thus which provides results relevant for approval. Investigations on temperature and calculated effective thermal conduction were performed on intumescent coatings in both experimental set-ups using various coating thicknesses. The results correspond to each other as well as showing the limits of transferability between both fire tests. It is shown that bench-scaled cone calorimeter tests are a valuable tool for assessing and predicting the performance of intumescent coatings in larger tests relevant for approval. The correlation fails for processes at surface temperatures above 750°C, which are not reached in the cone calorimeter, but are attained in the small scale furnace set-up. KW - Intumescent coatings KW - Cone calorimetry KW - Numerical analysis KW - Small scale test furnace PY - 2007 SN - 0308-0501 SN - 1099-1018 VL - 31 IS - 3 SP - 187 EP - 205 PB - Heyden CY - London AN - OPUS4-14645 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -