Filtern
Dokumenttyp
- Beitrag zu einem Tagungsband (18)
- Zeitschriftenartikel (9)
- Vortrag (6)
- Posterpräsentation (5)
- Beitrag zu einem Sammelband (2)
- Forschungsbericht (1)
Schlagworte
- Validation (11)
- Reliability (8)
- Strain sensor (7)
- Fiber Bragg grating (5)
- Strain transfer (5)
- Durability (4)
- Fibre Bragg grating (4)
- Fibre optic sensors (4)
- Fibre-optic sensor (4)
- Magnetic field (4)
- Patch (4)
- Strain (4)
- Application (3)
- Fiber bragg grating (3)
- Magnetostrictive metal coating (3)
- Self-diagnostic fiber optical sensor (3)
- Sensor characteristics (3)
- Structural health monitoring (3)
- Adhesive stability (2)
- Application-related changes (2)
- Electronic speckle pattern interferometry (2)
- Fiber Bragg gratings (2)
- Guideline (2)
- Magnetostriction (2)
- Magnetostriktive Beschichtung (2)
- Monitoring (2)
- Qualification (2)
- Standards (2)
- Strain gauge (2)
- Strain gauge factor (2)
- Surface application (2)
- Surface application reliability (2)
- 3D-image correlation (1)
- Actuators (1)
- Adhesive (1)
- Auto-validation (1)
- Bauteilmonitoring (1)
- Calibration (1)
- Composite materials (1)
- Condition diagnostics (1)
- Creep (1)
- Digital image correlation (1)
- ECD-Aktorschicht (1)
- Early damage detection (1)
- Embedded sensors (1)
- Evaluation (1)
- Faser-Bragg Gitter (1)
- Faser-Bragg-Gitter (FBG) (1)
- Faseroptik-Sensoren (1)
- Fatigue behavior (1)
- Fatigue behaviour (1)
- Fiber optic sensors (1)
- Fiber optics (1)
- Fiber-optic sensor (1)
- Finite element methods (1)
- Four-parametric (1)
- Harsh impacts (1)
- Laser extensometer (1)
- Long-term stability (1)
- Magneto-optischer Sensor (1)
- Maintenance (1)
- Materials behaviour (1)
- Modeling and simulation (1)
- Nickel-/Nickel-Eisen- Magnetostriktion (1)
- Offshore application (1)
- PVD-Haftfestigkeit (1)
- Push-out test (1)
- Rayleigh backscattering (1)
- Repair (1)
- Rosette (1)
- Selbstkalibrierung (1)
- Self-diagnosis (1)
- Sensors (1)
- Sensorvalidierung (1)
- Speckle-interferometry (1)
- Strain measurement (1)
- Structural Health Monitoring (SHM) (1)
- Superstructure (1)
- Temperature (1)
- Temperature sensitivity (1)
- Testing (1)
- Validation facility (1)
- model (1)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (6)
Fiber optic sensors are increasingly used because of their outstanding performance or if special requirements avoid the application of conventional electrical sensors. The scientific background for optical fiber sensors is well developed; however, the characteristic of sensors applied in rather harsh environment are almost always different from characteristics determined in laboratory or before its installation. In order to achieve long-term stable function and reliable measurement data after application and under harsh environmental conditions, guidelines for characterization and specification of sensor components are needed as well as methodologies for testing the sensor performance must be developed. Performance tests carried out revealed that there are still some restrictions with respect to long-term reliable use: first, some sensor products available on the market are not very often appropriately characterized, described and validated; second, application procedures are not always defined due to a lack of understanding the micromechanical issues in the interface zone between sensor and measuring object. Application procedures and profound knowledge of materials behaviour are necessary to get results from the sensor that can be reliably used. The paper describes first guidelines to prove the quality of fiber optic strain sensors, a testing facility developed for unbiased tests and certification of surface-applied sensors as well as result from comparison of commercially available strain sensors.
How do application-related issues influence the reliability of fiber optic strain measurements?
(2011)
Fibre optic strain sensors are increasingly used and sensor systems are provided with specifications. Even if the performance is well specified, the strain characteristics of the sensor, strain transfer factor, mechanical stability under thermal influences, the performance of applied strain sensors can seriously differ from virgin sensor's the performance. The contribution will focus on issues that can deteriorate the sensor function or reduce the reliability of measurement results. Aspects are considered how to come to reliable strain measurements and how to validate strain measurements of applied sensors. Related to this topic, European activities like the recently started European COST TD1001 action, called (OfSeSa) will be presented.
In Germany, the first guideline for the use of fiber Bragg grating strain sensors, 'Optical Strain Sensor based on Fiber Bragg Grating' (Berlin, Germany: Beuth-Verlag, 2010), has been developed by the GESA guideline group of VDI, 'The Association of German Engineers' and published by Beuth-Verlag. This guideline provides the basic specifications of this sensor type and the sensor characteristics, which have to be known for a reliable sensor performance. In conformity to this guideline, experimental investigations on the strain transfer characteristics of fiber Bragg grating patches have been carried out. A comparison between patches and resistance strain gauges during tensile tests and combined temperature and tensile loading was carried out. The evaluated strain gauge factor and the temperature sensitivity of the strain gauge factor have been compared to the manufacturer's data. The overall performance of the patches has been evaluated. The experimental investigations showed that there are considerable disagreements between the manufacturer's specifications and the observed characteristics.
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.
A high-performance fiber Bragg grating-based (FBG) sensor device has been developed for the detection of small magnetic fields. Based on a smart multilayer jacket around the fibre over the physical length of the FBG, magnetic fields generated by rotating machine parts, power generators or power cable can be easily detected, analysed and evaluated. Consequently, this innovative, on-line and non-contact inspection method results in an increase in quality and reliability of high-performing machine parts, devices and cables. The basic physical principle is based on a magnetostrictive multilayer system that strains the high-resolution FBG element in presence of magnetic fields. Subsequently, a fixed relationship between induced magnetic field and wavelength change of the FBG element describes the characteristic sensitivity curve. Intensive tests regarding characterisation of this magnetic field FBG sensor have been carried out and its performance has been evaluated.
A new concept for the self-diagnosis of embedded fiber Bragg grating (FBG) strain sensors was developed, simulated and experimentally tested. This concept is based on a magnetostrictive metallic layer directly coated on the fibre cladding over the grating segment of the FBG sensor, so that an on-demand external magnetic field in a millitesla scale can produce a controllable artificial strain as an indication signal for the remote optical interrogator. The relationship between the pre-defined magnetic field and its induced Bragg wavelength shift characterizes this validation concept. Any deviation of the local bonding state of the interfaces from the initial or/and any change of shear strain transferring mechanism from composite matrix to the optical fibre core will result in alterations in this sensitive relationship, and thus triggers an immediate alert for a further inspection. The finite element method is used to simulate the strain of this configuration as result of different values of the magnetic field in order to optimize the geometrical sensor parameters. The simulations are verified by experiments results. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.