TY - CONF A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Kusche, Nadine T1 - Calibration facility for quality certification of surface-attached fiber optic and electrical strain sensors N2 - Strain measurement in structures witli the purpose of long-term structurai health inonitoring must provide reliable inforination about the structure’s behavior over the whole period of use. The user must be sure that installed sensors are validated and work to the utmost satisfactiou. For this purpose, sensor Systems are tested using special facilities. Bccause it is not easy to characterize the strain transfer quality from the host structure into surface-applied strain sensors, a unique testing facility has been developed. Originally developed for fiber Bragg grating based sensors, the KALFOS facility (= calibration of fiber optic sensors) can also be used for electrical strain sensors. Calibration ineasurements are referenced by unbinsed Digital Image Correlation (D1C) and Electronic Speckle Pattern Interferometer (ESPI) methods. The strain transfer behavior can experimentally be analyzed and investigated under combined thermal and mechanical loading conditions and allows revealing wealuiesses in couimonly used attachment methodologies. The deformation of all members (particularly the coating/substrate - adhesive combination) in the sensing area is physically independently gained and recorded. Results achievcd allow precise description of the strain transfer function, Validation of the longterm strain sensor characteristics, matching of specific measurement requirements with environmental conditions, and, moreover, the verification of Standards for use of strain sensors. T2 - IEEE Sensors 2011 conference CY - Limerick, Ireland DA - 28.10.2011 KW - Fibre optic sensors KW - Structural health monitoring KW - Validation KW - Strain sensor KW - Surface application reliability PY - 2011 SN - 978-1-4244-9288-6 U6 - https://doi.org/10.1109/ICSENS.2011.6127253 SP - 1337 EP - 1340 AN - OPUS4-24655 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Schilder, Constanze A1 - Köppe, Enrico A1 - Habel, Wolfgang ED - Chang, F.-K. T1 - Development and qualification of FBG-based strain patches and rosettes N2 - A fibre Bragg grating (FBG) strain patch specially adapted for long-term and high-strain applications was developed and characterised. Additionally, in the case of unknown main stress axis, two fibre optic strain rosettes were developed. The design concept for the patch and the rosettes is based on a glass fibre reinforced plastic (gfrp) carrier material. The patches were characterised due to their strain gauge factor and fatigue behaviour. As a result, FBG strain patches with linear strain behaviour and excellent fatigue resistance were developed and can be used as part of a monitoring system for aerospace structures or wind turbine power plants. The rosettes were designed to be small in geometrical size and their strain transfer behaviour was characterised. T2 - 8th International workshop on structural health monitoring 2011 CY - Stanford, CA, USA DA - 13.09.2011 KW - Fibre Bragg grating KW - Patch KW - Rosette KW - Strain gauge factor KW - Fatigue behaviour KW - Validation PY - 2011 SN - 978-1-60595-053-2 VL - 2 SP - 1457 EP - 1465 PB - DEStech Publications, Inc. AN - OPUS4-24512 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Schilder, Constanze A1 - Kusche, Nadine A1 - Schukar, Vivien A1 - Habel, Wolfgang ED - Liao, Y. ED - Jin, W. ED - Sampson, D.D. ED - Yamauchi, R. ED - Chung, Y. ED - Nakamura, K. ED - Rao, Y. T1 - Experimental qualification and validation of fibre optic strain sensors N2 - Strain sensors used in practical applications must provide reliable measurement data. To achieve this, sensor systems must be validated by using experimental facilities that enable physically independent statements about the performance of the sensor components. The paper describes qualification and validation procedures using a special facility to qualify surface-applied strain sensors and to achieve reliable sensor results. Based on examples concerning fibre optic strain sensor patches with and without FBG sensors, the determination of the strain gauge factor also under combined thermal and mechanical loading will be presented. These results are the basis for development of guidelines and standards. T2 - OFS2012 - 22nd International conference on optical fiber sensors CY - Beijing, China DA - 2012-10-15 KW - Fiber Bragg gratings KW - Sensors PY - 2012 U6 - https://doi.org/10.1117/12.968801 SN - 0277-786X SN - 1996-756X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE IS - 8421 SP - 1 EP - 4(?) PB - SPIE, the International Society for Optical Engineering CY - Bellingham, Wash. AN - OPUS4-27321 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 - Kusche, Nadine A1 - Münzenberger, Sven A1 - Schukar, Vivien T1 - KALFOS - a validation facility for strain transfer characterization of surface-applied strain sensors N2 - Strain sensors embedded in or attached to structural components have to measure the real deformation of the structure over the whole period of use. The user must know how reliably installed sensors provide strain measurement results. For this purpose, test facilities or coupon tests are used. In order to characterize the strain transfer quality from the host structure into surface-applied strain sensors, a unique testing facility has been developed. This facility can be used both for fiber optic and resistance strain sensors. Originally developed for fiber Bragg grating based sensors, the KALFOS facility (=calibration of fiber optic sensors) uses Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometer (ESPI) as unbiased referencing methods. It is possible to determine experimentally the strain transfer mechanism under combined thermal and mechanical loading conditions. This experimental characterization method will reveal weaknesses in commonly used strain sensors, and the investigation of the material systems used for fiber optic and other strain sensors (particularly the coating/substrate - adhesive combination). The KALFOS facility allows matching of specific measurement requirements with environmental conditions. T2 - SAE 2011 AeroTech Congress & Exhibition CY - Toulouse, France DA - 18.10.2011 KW - Fiber optic sensors KW - Structural health monitoring KW - Validation KW - Strain sensor KW - Surface application PY - 2011 U6 - https://doi.org/10.4271/2011-01-2606 IS - Paper 2011-01-2606 SP - 1 EP - 7 AN - OPUS4-24643 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Habel, Wolfgang A1 - Schukar, Vivien A1 - Kusche, Nadine ED - Peters, K.J. ED - Ecke, W. ED - Matikas, T.E. T1 - The role of experimental validation in achieving reliable measurement data with applied FBG strain sensors N2 - Fiber-optic strain sensors are increasingly used in very different technical fields. Sensors are provided with specifications defined by the manufacturer or ascertained by the interested user. In some cases, sensor specification is not sufficiently validated and must therefore additionally be validated in a laboratory, primarily to ensure reliable measurement information over the intended period of operation. Even if the performance of delivered sensor is well specified, the sensor's strain characteristics and the performance of an applied sensor can significantly differ from the virgin sensor's performance. In this case, applied sensors do not provide full reliability and lead sometimes to uncertain measurement results. This contribution will therefore focus on the role of validation in avoiding a decrease or even deterioration of the sensor function of applied sensors. Experimental validation - not only modelling - is very important, however, before experimental investigations are planned knowledge about key issues and problems that influence the measurement results must be available. Few aspects to be considered and investigated will be discussed. Selected experimental facilities to reveal weaknesses in the sensor function will be described; an outlook to open questions is given. T2 - Smart sensor phenomena, technology, networks, and systems integration 2013 CY - San Diego, CA, USA DA - 2013-03-10 KW - Fibre-optic sensor KW - Strain sensor KW - Reliability KW - Durability KW - Sensor characteristics KW - Application-related changes KW - Adhesive stability KW - Validation PY - 2013 U6 - https://doi.org/10.1117/12.2009677 SN - 0277-786X N1 - Serientitel: Proceedings of SPIE – Series title: Proceedings of SPIE VL - 8693 IS - Paper 12 SP - 86930C-1 - 86930C-11 AN - OPUS4-29911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -