Abstract
Targeted heating of nano-Fe3O4 reinforced thermoplastics using electromagnetic (EM) radiations allows for rapid dis-assembly and re-assembly of bonded structural joints. Alternate EM field causes local heating of the dispersed ferromagnetic nanoparticles (FMNP), thereby melting the surrounding thermoplastic. However, it is essential to accurately measure the temperature of the adhesive since overheating may cause degradation and underheating may introduce inefficient bonding. This paper presents an ultrasonic guided wave (GW) technique for monitoring the adhesive state and provides feedback to control the electromagnetic process. Experiments were performed on single lap-shear joints FMNP reinforced thermoplastics and non-conductive glass fiber reinforced polymer (GFRP) adherends. GW were made to propagate across the bond-line of the joint by actuating and sensing them using miniature piezoelectric wafers. Dispersion relations and dynamic wave propagation were obtained using finite element (FE) modeling. Fundamental longitudinal mode L0 at 35 kHz was found optimal for bond process monitoring. Mapping between the FE-simulated transmission coefficient of L0 and actual temperature of the thermoplastic adhesive was established using the dynamic mechanical analysis (DMA) test data. Real-time GW measurements were used as a feedback in the discrete control of the induction heater to provide optimal bonding. The developed ultrasonic technique was successfully validated by a high resolution, optical frequency domain reflectometer (OFDR) based fiber-optic temperature sensor which was embedded inside the adhesive bond-line. Experiments demonstrated good agreement between GW measurements and OFDR system. Overall, the results indicate the potential of GW technique for in-situ monitoring and controlled bonding of reversible lap-joints using electromagnetic heating.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
