Design and Fabrication of Carbon Nanotube-Based Multifunctional Composites and Advanced Sensors for Composites Manufacturing

Polymer matrix composites are increasingly used in aerospace applications due to their high specific properties. Recently, wide application of composite materials leads to extensive research in improving manufacturing processes to increase production quality as well as potentially reduce cost. In addition, adding new functionality such as sensing, communication, lightning strike protection into composite structures to make multifunctional composites has gained more and more interests. Incorporation of functionalities triggers the development of integration technologies as well as innovate manufacturing approaches such as 3D printing or additive manufacturing. In this research, the design and fabrication of multifunctional composites by using different techniques including in-situ curing, 3D printing, and printed sensor network on composite structures are studied. In-situ curing in CNT/CF hybrid composites is presented in this work as an effective technique to manufacture multifunctional composites. By passing electrical current through highly conductive CNT layers, composite is fully cured by heat generated from CNT layers. FEM simulation is used to demonstrate uniformity of composite temperature which was in good agreement with the experiment result. In addition, 3D printing of functional ink using graphite nanoplatelets and milled carbon fiber is discussed. We successfully formulated conductive ink with thermal conductivity of 2W/mK and a density of 1.21 g/cm3. This research also introduced a new way of fabricating lightweight heat sink for thermal management by a combination of 3D printing technology with carbon nanotube sheet. Our heat sink offered effective thermal performance and extremely lightweight. Results indicate that the techniques are effective ways to transfer the properties of CNT sheets into lightweight thermal devices for thermal management applications. Furthermore, this work demonstrated feasibility and preliminary results of a fully printed wireless sensor that can potentially operate, monitor and transfer high quality of signal such as a change in relative permittivity. The sensors can effectively detect the change in permittivity of the environment Printed wireless sensor could open cost-effective and efficient way to monitor the large composite structure or manufacturing process.