Structural health monitoring of composite laminates in thermoplastic induction welded joints using electromagnetic field technique

• Published in: Sensors and actuators. A. Physical. 2024-09, Vol.375, p.115540, Article 115540
• Main Authors: Mazzeschi, Mattia, Farhangdoust, Saman, Cañibano, Esteban, Merino, Juan C., Núñez, Karina C.
• Format: Article
• Language: English
• Subjects: Damage detection; Electromagnetic-based structural health monitoring; Induction welding; Thermoplastic composite
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2024.115540

This research paper explores the assessment of electrical property changes resulting from damage in a Carbon Fiber Reinforced Polymers (CFRP) laminate and its thermoplastic induction-welded joints. Controlled variations in electrical conductivity and dielectric permittivity were achieved by incorporating square Polytetrafluoroethylene (PTFE) adhesive tapes into both CFRP laminates and the bondline interfaces of induction-welded components. Two elementary and effective sensors, capable of measuring magnetic (Purely Magnetic sensor) and electric fields (Hybrid sensor), were employed to detect these property changes induced by a sinusoidal magnetic field generated by a nearby coil. Both sensors exhibited remarkable sensitivity in identifying variations induced by the smallest artificial defects, measuring 2×2 mm in size. Furthermore, the PM sensor displayed a discernible signal trend corresponding to changes in defect size ranging from 4 to 225 mm square, as well as variations in position within the thickness of the CFRP laminate, extending to a depth of 1.7 mm. These findings underscore the potential of electromagnetic-based structural health monitoring (ESHM) techniques for monitoring the condition of a thermoplastic composite structure and its induction-welded joints. [Display omitted] •Controlled variations of electrical conductivity and dielectric permittivity by incorporating PTFE adhesive tapes•Two sensors capable of measuring defect induced magnetic and electric fields variations.•Both sensors shows discernible signal trend corresponding to changes in defect size.•A potentially effective electromagnetically based SHM method for monitoring defects in CFRTP laminates is presented.