Smart composites with embedded magnetic microwire inclusions allowing non-contact stresses and temperature monitoring

A novel sensing technique for non-destructive and non-contact monitoring of the composites utilizing ferromagnetic glass-coated microwire inclusions with magnetic properties sensitive to tensile stress and temperature is proposed. We provide in-situ studies of the evolution of the hysteresis loop of arrays consisting of Co- and Fe-rich microwires, as well as transmission and reflection parameters of the composites with microwire inclusions during the composites matrix polymerization. We observed remarkable change of the hysteresis loops upon matrix polymerization: remarkable coercivity change and transformation of linear hysteresis loop to rectangular or from rectangular to linear for arrays with Co-rich and Re-rich microwires respectively. Using the free space technique we observed considerable variation of the reflection in the range of 4-7 GHz and transmission upon the matrix polymerization. Observed dependencies are discussed considering variation of temperature and stresses during the thermoset matrix polymerization and their influence on magnetic properties of glass-coated microwires.