Guided wave monitoring of Nano-Fe3O4 reinforced thermoplastic adhesive in manufacturing of reversible composite lap-joints using targeted electromagnetic heating. (September 2021)

• Record Type: Journal Article
• Authors: Palanisamy, Rajendra Prasath; Karpenko, Oleksii; Vattathurvalappil, Suhail Hyder; Deng, Yiming; Udpa, Lalita; Haq, Mahmoodul
• Is Part Of: NDT & E international. Volume 122(2021)
• Publication Date: 2021-09
• Subjects: Guided wave health monitoring -- Electromagnetic heating -- Ferromagnetic nanoparticles -- Thermoplastic adhesives -- Lap-shear joints -- Optical frequency domain reflectometry; Nondestructive testing -- Periodicals; Contrôle non destructif -- Périodiques; Electronic journals; 620.1127
• DOI: 10.1016/j.ndteint.2021.102481
• Languages: English
• ISSNs: 0963-8695

Abstract

Abstract: Targeted heating of nano- Fe 3 O 4 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 L 0 at 35 kHz was found optimal for bond process monitoring. Mapping between the FE-simulated transmission coefficient of L 0 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.