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During fiber composite production, the quality of the manufactured parts can be assured by measuring the progress of the curing reaction. Dielectric film sensors are particularly suitable for this measurement task, as they can quantify the degree of curing very specifically and locally. These sensors are usually manufactured on PI films, which can lead to delaminations after integration. Other authors report that this negative influence can be reduced by miniaturization and a suitable shaping of the sensors. This article pursues as an alternative, a novel approach to achieve a material closure instead of a geometrically generated form closure by choosing suitable thermoplastic materials. Thermoplastic films made of PEI, PES and PA6 are proposed as carrier substrates for thin film sensors. They are investigated with regard to their mechanical effects in FRP. The experiments show that the integration of PES and PEI in FRP has the best shear strength, but PA6 leads to a higher critical energy release rate during crack propagation in mode I. For PI, a locally strongly scattering critical energy release rate was observed. Neither in tensile nor in Compression After Impact (CAI) tests a significant influence of the films on these characteristic values could be proven. [ABSTRACT FROM AUTHOR]

During fiber composite production, the quality of the manufactured parts can be assured by measuring the progress of the curing reaction. Dielectric film sensors are particularly suitable for this measurement task, as they can quantify the degree of curing very specifically and locally. These sensors are usually manufactured on PI films, which can lead to delaminations after integration. Other authors report that this negative influence can be reduced by miniaturization and a suitable shaping of the sensors. This article pursues as an alternative, a novel approach to achieve a material closure instead of a geometrically generated form closure by choosing suitable thermoplastic materials. Thermoplastic films made of PEI, PES and PA6 are proposed as carrier substrates for thin film sensors. They are investigated with regard to their mechanical effects in FRP. The experiments show that the integration of PES and PEI in FRP has the best shear strength, but PA6 leads to a higher critical energy release rate during crack propagation in mode I. For PI, a locally strongly scattering critical energy release rate was observed. Neither in tensile nor in Compression After Impact (CAI) tests a significant influence of the films on these characteristic values could be proven.

The curing behavior of thermosetting polymer materials is crucial to the quality and performance of their composite products, which promotes the development of the curing process monitoring. A novel strategy for real-time monitoring of the curing process of thermosetting resin using magnetic fiber (MF) with sensitive stress impedance effect is proposed. Differential scanning calorimetry and dynamical mechanical analysis are performed to obtain the curing degree, modulus, and glass transition temperature (T g) as a calibration curve to establish a relationship with the impedance of MF embedded in resin during the curing cycle, which is determined by the internal stresses around the MF mainly induced by the crosslinking reaction and cooling shrinkage of resin. The dynamic physical properties of epoxy resin during curing process can be effectively and continuously monitored in real-time through the curing electrogram from the integrated MF sensor signal output, which can digitalize the evolution of resin crosslinking reaction and capture the gelation point, T g and local mechanical state. The MF sensors for curing process monitoring is a promising technology to be developed into a life-cycle structural health monitoring of polymer composites and instrumental to their smart manufacturing advancement. [Display omitted] [ABSTRACT FROM AUTHOR]