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Rapid Processing of Thermoset Composites Using Electromagnetic Fields
Abstract
This work addresses the out-of-oven processing of thermoset composites using electromagnetic (EM) fields. Recently, radio-frequency (RF) fields have been explored to rapidly and selectively heat conductive carbon materials. This phenomenon has opened up pathways for out-of-oven, energy efficient methodologies for materials synthesis and processing applications. This thesis is part of a thrust to integrate EM-induced heating into thermoset and composite manufacturing processes at an industrial scale.
A major portion of my research is focused on designing additive manufacturing methodologies for rapid production of thermoset-based nanocomposites. Current state-of-the-art technology for thermoset manufacturing involves oven-curing the resin in a mold. The process is highly energy-consuming and labor-intensive. The need of the hour is to come up with an additive manufacturing technique that enables rapid, free-form production of such parts in an energy efficient manner. A coplanar RF applicator was successfully used to rapidly heat and cure nano-filled thermosetting resins. RF heating was coupled with a conventional Direct Ink Writing (DIW) setup to successfully print multi-layered, nanocomposite structures.
The other broad area of my research involves the processing of continuous carbon fiber composites using electromagnetic fields. I have worked on three projects in this field: fabrication of carbon fiber composites, repair of carbon fiber composites, and recycling of carbon fiber composites. These three projects broadly address the entire life cycle of such composites, which are widely used in automotive and aerospace industries. The first project deals with rapid fabrication of composites using radio-frequency fields, and characterization and comparison against conventional, oven-cured composites. The second project involves the repair of cracks and dents in such composites, which are a result of repeated use, mechanical impact, and fatigue. Here, we have used low-frequency electric field plasma generated using a Dielectric Barrier Discharge (DBD) applicator; the electric field heats up a ‘patch’ of resin-impregnated carbon fiber tow, which acts as a structural additive to the damaged part. Finally, I have also worked on using Direct Current (DC) heating for recycling of carbon fiber composites. With age, mechanical stress and chemical degradation, the matrix holding the fibers together become unfit for further applications. But the fibers themselves remain pretty much unaffected. DC Heating can be used to heat these composites up to the target degradation temperature required to degrade the matrix; the underlying fibers can be reclaimed and re-infiltrated with resin to make composites again.
Subject
Electromagnetic fieldsRadio-frequency heating
Composites
Carbon materials
Additive Manufacturing
Citation
Sarmah, Anubhav (2023). Rapid Processing of Thermoset Composites Using Electromagnetic Fields. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /199806.