German Research Foundation (DFG) - Project number: 553258609
The basic idea of the research project is based on the electrical conductivity of carbon fibers and their change in resistance when stretched. With this “self-sensing” approach, a possibility for complete sensor integration in fiber composite structures is being pursued.
Since the integrated sensor and the surrounding component are made of the same material, this approach can minimize negative effects of the sensor on the mechanical properties of the material due to different moduli of elasticity or expansion coefficients.
In this research project, the pultrusion process in particular is being investigated as a manufacturing method for sensors made of carbon fiber reinforced plastic (CFRP), as it enables the cost-effective production of sensors of almost any length. This is particularly interesting for use in very large components, such as CFRP belts of rotor blades for wind turbines.
Stretching the sensor in the longitudinal direction leads to a change in resistance. This phenomenon enables the use of CFRP for load monitoring of structures.
In piezoresistive sensors, the k-factor describes the sensitivity of the sensor and represents the relationship between the normalized change in resistance and the strain. The literature research indicates that the k-factor of carbon fibers is around 2, which corresponds to the value of conventional strain gauges, making these sensors suitable for load monitoring.