Dielectric Sensors

Crosslinked plastics are used for multilayer composites such as coatings and adhesive bonds as well as for fiber-reinforced plastics (FRP) such as e. g. carbon fiber reinforced polymers (CFRP). For the metrological recording of the manufacturing process of these materials and also their long-term behavior methods with potential excitation as impedance spectroscopy have proven. These methods allow e. g. to monitor the polymerization of a component made of CFRP with an embedded dielectric sensor. In the process of polymeri-zation the movement of ions is inhibited, resulting in a change of permittivity and the resis-tive properties of the material. These measurements make it possible to monitor online the process of curing. This guarantees a consistent quality through an online process monitor-ing (OPM) and minimizes process times. Sensors for this task exist, but these are relatively large, so that the elements represent a foreign body in the material, which cannot be tolerated in the continuous operation of a component. That is why these sensors are only usable in laboratory tests for component development. If the sensors would be very small and well-adapted to the polymer matrix then it should be possible to let the sensors embedded in the material during the continuous operation of the composite structure. In the project minimally invasive film sensors are developed and embedded in FRP composite materials in order to obtain important information about the condition of the materials with these sensors. At the same time, these sensor structures should be designed in such a way that no significant weakening of the composite material structure arises by the embedded foreign body, so that the sensors can remain in the composite structure over the entire product life-cycle. The goal of the project is the verification of this approach. The processes for preparing the appropriate sensor structures and for their embedding as well as the procedures for analy-sis and evaluation of sensor data are still unknown today. The required basic scientific in-vestigations are carried out in the project…read more