Filtern
Dokumenttyp
- Beitrag zu einem Tagungsband (8)
- Zeitschriftenartikel (6)
- Posterpräsentation (2)
- Vortrag (1)
Schlagworte
- Validation (7)
- Fibre Bragg grating (5)
- Patch (5)
- Strain transfer (5)
- Fiber Bragg grating (3)
- Strain sensor (3)
- Structural health monitoring (3)
- Electronic speckle pattern interferometry (2)
- Fibre optic sensors (2)
- Fibre-optic sensor (2)
Eingeladener Vortrag
- nein (1)
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.
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.
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.
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.
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.