Real-time evaluating temperature-dependent interfacial shear strength of thermoplastic composites based on stress impedance effect of magnetic fibers

Abstract

Thermoplastic composites are susceptible to service environments. Precise evaluation of the temperature-dependent interfacial shear strength (IFSS) is essential for determining and predicting mechanical properties and service life. However, a great challenge exists in the measurement of temperature-dependent IFSS by micromechanical tests, due to polymer deformation at elevated temperatures. Here, we report a novel prediction methodology based on the interfacial stress impedance effect of magnetic fibers (MFs) for non-destructive and real-time evaluation of temperature-dependent IFSS. The MFs are optimized by annealing and surface modification to obtain a linear relationship between the impedance property of MF and the radial compressive stress. Through the impedance measurement and corresponding IFSS micromechanical test, a correlation model between the IFSS of composite and the impedance of MF is established. The IFSS at elevated temperatures calculated by this model are consistent with the results of the micromechanical test by more than 95 %, and allows for evaluating the IFSS of composites beyond the glass transition point. The prediction methodology utilizing MF features the merits of convenient operation from the impedance measurement as well as high reliability and wide operating temperature from the nonmechanical and nondestructive test, paving a novel avenue to real-time evaluate temperature-dependent IFSS of advanced thermoplastic composites.