Smartly pre-packaged optical sensors
The motive for this research began with the need to transport flammable and explosive materials like hydrogen and natural gas safely. They are both transported under high pressure in tanks made out of composite materials. Obviously, lack of integrity of such a vessel would have catastrophic consequences. Composite materials are usually manufactured as many filaments, tapes or sheets simply stuck together. In order to monitor the mechanical properties, like shear stress of these layers, an optical fibre sensor is embedded in the structure. Unless properly bonded within the material, the sensor may affect the structure's properties, causing for instance lamina instabilities. Ironically then, the sensor itself can be the cause of mechanical failure. The sensor can also be mounted on the surface of the structure where it is then obviously subjected to environmental degradation. The ZEM project set out to dispense with all the above problems and a project partner was able to manufacture a really SMARTape optical sensor that also has market applications outside the field of application of this project. A fibre-reinforced composite tape with integrated optical fibre can easily and safely be embedded in a composite structure and just as easily be mounted on top of it. The sensors, prior to their market application, were of course extensively tested. Their properties include excellent mechanical, thermal and chemical performance. Moreover, they are compatible with other systems, in particular long-gauge interferometric SOFO sensors, well known in the civil engineering field. SOFO sensors have been in use for the last ten years for the monitoring of civil, geotechnical, oil and gas structures. The SMARTape optical fibre sensor is expected to find a number of applications in many multi-disciplinary areas of science and industry.
