TY - JOUR A1 - Schukar, Vivien A1 - Baitinger, Eugen A1 - Kusche, Nadine A1 - Steinke, F. A1 - Habel, Wolfgang T1 - Use of spectral conditions to separate strain and temperature effects in fibre Bragg grating sensors embedded in load-carrying anisotropic laminates N2 - This work presents a further development of the methods of simultaneous determination of temperature and axial strain using a single fibre Bragg grating (FBG). The reflected spectrum of composite-embedded FBG sensors has been analyzed in order to separate temperature and load effects. We found out that during the curing process of the laminates, a superstructure has been introduced on the FBG. Analyzing this effect, a temperature and strain separation was implemented by simply calculating and comparing the integrated intensity of the spectral response signal. A mathematical four-parametric model has been developed to calculate the reflected spectrum of a superstructured fibre Bragg grating. The mathematically achieved data has been evaluated with experimentally determined data from fibre Bragg gratings embedded in glass-fibre reinforced composite materials. KW - Fibre Bragg grating KW - Patch KW - Four-parametric KW - model KW - Superstructure KW - Temperature KW - Strain PY - 2013 U6 - https://doi.org/10.1007/s11340-013-9773-y SN - 0014-4851 SN - 1741-2765 VL - 54 IS - 3 SP - 421 EP - 429 PB - Springer CY - Norwell, Mass. AN - OPUS4-29452 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schilder, Constanze A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Münzenberger, Sven A1 - Habel, Wolfgang T1 - Experimental qualification by extensive evaluation of fibre optic strain sensors N2 - Fibre optic strain sensors used in practical applications have to provide reliable measurements. Therefore, the applied sensor and the sensor systems must be validated experimentally. This can be achieved with facilities which use physically independent measurement systems in order to avoid the influences caused by the application of a reference sensor. This paper describes the testing methods of the specially developed validation facility KALFOS for the qualification and evaluation of surface-applied strain sensors. For reliable sensor results, the performance of fibre optic strain patches with and without FBG under combined thermal and mechanical loading was investigated. Additionally, the strain gauge factor of the fibre optic strain patches with FBG was determined experimentally and compared to the specified strain gauge factor. These results will be the basis for the development of guidelines and standards concerning the application of the sensors. KW - Evaluation KW - Qualification KW - Strain transfer KW - Fibre optic sensors KW - Fibre Bragg grating KW - Patch KW - Strain gauge KW - Validation facility KW - Laser extensometer KW - Electronic speckle pattern interferometry PY - 2013 U6 - https://doi.org/10.1088/0957-0233/24/9/094005 SN - 0957-0233 SN - 1361-6501 VL - 24 IS - 9 SP - 094005-1 EP - 094005-7 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-29424 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Hofmann, Detlef A1 - Basedau, Frank A1 - Habel, Wolfgang A1 - Woschitz, H. A1 - Lienhart, W. ED - Jaroszewicz, L.R. T1 - Field examples for optical fibre sensor condition diagnostics based on distributed fibre-optic strain sensing N2 - Fibre optic sensors for monitoring in safety-relevant structures have to be validated in order to proof their reliability under typical structural load conditions. The reliable use of optical fibre sensors depends strongly on an appropriate and qualitative application. Diagnostics of the physical condition of embedded and surface-applied fibre optic strain sensors are demonstrated on field examples. Distributed strain measurement based on Rayleigh backscattering is used to determine breakage of the fibre, interface adhesion problems and to identify application related strain transfer mechanisms. T2 - EWOFS 2013 - 5th European workshop on optical fibre sensors CY - Kraków, Poland DA - 19.05.2013 KW - Fibre Bragg grating KW - Rayleigh backscattering KW - Condition diagnostics KW - Strain KW - Strain transfer PY - 2013 SN - 978-0-81949-634-8 U6 - https://doi.org/10.1117/12.2025567 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8794 IS - Paper 8794 - 181 SP - 879433-1 EP - 879433-4 AN - OPUS4-28570 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Tkachenko, Viktoriya A1 - Hofmann, Detlef A1 - Basedau, Frank ED - Xu, Y. L. ED - Zhu, S. ED - Xia, Y. ED - Ni, Y.Q. ED - Law, S.S. ED - Yin, J. H. ED - Su, Z.Q. T1 - Values gained from composite-embedded sensor fibres - trustworthy results or vague estimations; possibilities and limitations of getting reliable measurement results T2 - SHMII-6 - 6th International conference on structural health monitoring of intelligent infrastructure CY - Hong Kong, China DA - 2013-12-09 KW - Composite materials KW - Embedded sensors KW - Monitoring KW - Early damage detection KW - Validation KW - Reliability KW - Maintenance KW - Repair PY - 2013 SN - 978-962-367-768-4 SP - 1 EP - 11(?) AN - OPUS4-29912 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Kusche, Nadine T1 - Fibre-optic strain sensors are making the leap from lab to industrial use-reliability and validation as a precondition for standards N2 - Currently, fibre-optic sensors (FOSs) are commonly used if special requirements make the application of electrical sensors impossible, or economic benefit is promised. The scientific background of FOS technology is well developed; however, there are still some restrictions with respect to long-term reliable use. For widespread practical use, sensor products must be manufactured, characterized and validated according to standards. Guidelines on how to apply sensors and evaluate their operation on-site including special facilities to evaluate applied sensors are needed. This paper will focus on important aspects, such as when FOSs may be used under real practical conditions, and will present validation methodologies to evaluate the overall quality of the sensor system's function. It will also indicate the lack of knowledge and methods to be elaborated to promote the use of FOS. KW - Fibre-optic sensor KW - Application KW - Reliability KW - Validation KW - Strain transfer KW - Standards KW - Guideline PY - 2013 U6 - https://doi.org/10.1088/0957-0233/24/9/094006 SN - 0957-0233 SN - 1361-6501 VL - 24 SP - 094006-1 - 094006-13 PB - IOP Publ. Ltd. CY - Bristol AN - OPUS4-29916 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -