A smart multi-functional printed sensor for monitoring curing and damage of composite repair patch

A novel multifunctional diagnostic sensor is developed as a cost-effective, in-service structural health monitoring (SHM) system for determining the initial quality of curing of a bonded composite repair patch and assessing its long-term durability on composite structure. The proposed multi-functional sensor technology involves the creation of a "tailor-to-order" 2D conductive patterns onto step-sanded repair surface of composite repair patch using inkjet printing. In employing this methodology, bondline quality during curing and in service was successfully assessed via Impedance spectroscopy and resistance change measurements, respectively. The ability of this technology to effectively monitor the integrity of the bondline and the extent of damage in real-time was investigated by subjecting the scarf-repaired CFRP panels to 3-point bending fatigue and low-velocity impact tests. The obtained results were compared with those of transient infrared thermography (IrT) and ultrasound inspection techniques, thus validating the proposed method

Quality assessment and damage detection in nanomodified adhesively-bonded composite joints using inkjet-printed interdigital sensors

In this work, the development of a planar interdigital capacitive sensor, directly onto the surface of a composite, for determining the initial quality of curing of bonded composite joints and assessing their long-term durability is presented. The sensor consisted of an interlocking comb-shaped array of silver electrodes and used to monitor the progress of cure of an adhesive resin and the subsequent damage state of the bond line in adhesively-bonded composite joints using impedance spectroscopy. The obtained results from the mechanical characterization indicated that the developed sensor did not affect the quality of the bondline while the added weight of the sensor is negligible. The curing process of the adhesive epoxy was successfully monitored while the ability of the sensor to assess the developed damage created by the mechanical loading was confirmed using transient infrared thermography

Smart bondline monitoring of an efficient industrial thermoplastic aircraft window frame

In this work, a smart thermoplastic window frame for a regional aircraft has been designed and manufactured. The aim of the work was to design a smart sensing system for monitoring of a bonded thermoplastic aircraft window frame in operation. The conductive tracks were designed and inkjet-printed onto the window frame and their disruption was used as an indication of a damage event created within the bondline. Based on the electrical resistance measurements, the method was able to detect a damage that was created in the bondline due to an impact event. To verify the proposed methodology, ultrasonic C-scan inspection was also performed

Microcapsule-based self-healing materials: Healing efficiency and toughness reduction vs. capsule size

We report the synthesis of controlled sized Urea-Formaldehyde (UF) microcapsules containing an epoxy healing agent via in situ emulsification polymerization for the study of self-healing epoxy systems. Scanning Electron Microscopy (SEM) confirmed that the capsules possessed rough external surface which enhanced mechanical interlocking. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy were employed so as to determine the capsules thermal stability and decompositions and encapsulated healing agent percentage. To our knowledge it is the first time the solid-state NMR is used for the estimation of encapsulated healing agent. The obtained results clearly indicated that with decreasing capsule size, capsules remained thermally stable at high temperatures (approximetly up to 230 °C). Additionally, capsule size is for the first time directly correlated to both healing efficiency and the reduction of mechanical performance after self-healing system incorporation. Healing efficiency is proportional to capsule size with larger capsules resulting in 68% maximum load recovery. However, smaller capsules result to lower reduction of properties, i.e. 7% as oppose to 18% for larger ones. Although healing efficiency can be enhanced through the use of relatively large capsules, this is in expense of mechanical performance, i.e. there is an optimal capsule size

Green Biocomposites for Packaging Applications

In recent years, research on environmentally sustainable packaging has been gaining momentum, primarily driven by consumer ecological consciousness. Green biocomposites play an important role in novel and innovative materials for the emerging sustainable packaging industry, being intrinsically biobased and biodegradable. Therefore, the following chapter is aimed to make an overview of the main trends on green biocomposites study and development, their environmental impact and their importance in future production systems. A revision of the polymeric matrices and fillers most widely used for green biocomposites and bionanocomposites manufacture is done, and the results of the latest investigations on the subject are discussed. Besides, their role in active and intelligent packaging is reviewed as well as their implementation for 3D printing technologies. Finally, the relevance of these materials study and development in terms of environmental impact is herein considered, remarking the importance of adequate life cycle assessment of the developed green biocomposites in comparison to conventional materials used for similar packaging applications.Fil: Versino, Florencia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. Universidad Nacional de La Plata. Facultad de Ingenierí­a. Departamento de Ingeniería Química; ArgentinaFil: Lopez, Olivia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: García, María Alejandra. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentin