Pre-use interfacial shear strength prediction for fiber-reinforced thermosetting composites based on stress-impedance effect of ferromagnetic microwires

A new rapid evaluation method of composite interfacial shear strength (IFSS) on basis of impedance parameter utilizing the glass-coated cobalt-based ferromagnetic microwire (GCM) with sensitive stress-impedance effect is proposed. The intrinsic properties analysis and surface modification of GCM were performed to improve the sensitivity of stress-impedance effect and meet the application requirements in composites. The correlation between impedance increments and interfacial stress is investigated for GCM composites with different resin embedded lengths through experimental verification and finite element simulation. The impedance increment of microwire shows a high degree of dependence on IFSS of GCM/resin systems, which is mainly associated with the local interfacial stress from the resin. Based on this correlation mechanism and IFSS measured by microdroplet debonding test, IFSS of composites with different resin matrix were successfully calculated from the impedance parameter, and the interfacial bonding of resin matrix could be distinguished and sorted as relatively superior or inferior conveniently and rapidly. In comparison with the sophisticated, lengthy and expensive interface mechanical tests after the manufacture of fibers and resin, the pre-use efficient interfacial assessing of resin matrixes only using GCM shows potential to screen resin matrix with excellent interfacial properties towards advanced fiber-reinforced thermosetting resin matrix composite.