Influence of Tensile Stress on Microwave Scattering Parameters of Continuous Ferromagnetic Microwire Embedded Into Glass Reinforced Composites

In this work, continuous ferromagnetic microwires were integrated into glass fiber-reinforced composite (GFRP) plates. The microwires were placed in a single orientation maintaining a constant distance between them. A vector network analyzer (VNA) and two antennas were placed in the vicinity of the composite plates that were mounted in a universal testing machine. Therewith, reflection and transmission scattering parameters were determined by means of free space measurements, while simultaneously, the composite test specimens were submitted to tensile stresses. Force was progressively increased, and dynamic stress cycles were also applied. No external magnetic fields were applied to the composite structures during the measurements. The obtained results were compared with those generated with the same procedure applied to composite specimens without integrated microwires. The result reveals a clear dependence of scattering parameters with tensile force applied. Outcomes are considered as a baseline for a new detection method that can be further developed. This would allow to monitoring of GFRP in a non-destructive and contactless operation by embedding continuous ferromagnetic microwires within their structure.