Date of Award

Spring 2022

Document Type

Open Access Thesis

Department

Computer Science and Engineering

First Advisor

Paul Ziehl

Abstract

Aerospace manufacturing has seen continually increased use of carbon fiber reinforced polymers in aircraft structures. The favorable strength to weight ratios, as well as the increased resistance to fatigue and corrosion, compared to metallic structures, provide a common argument for further research and development of composite airframes. Two main classes of carbon fiber reinforced polymers can be distinguished, thermosetting polymers and thermoplastic polymers. Thermoset polymers have been relied on for decades for the ability to reliably produce strong laminates for aircraft structures. By comparison thermoplastic polymers experience less comparable utilization on primary structures despite boasting similar or greater performance capabilities due to their processing requirements. The path to bridging the utilization gap between the polymers begins with advancing thermoplastic composite manufacturing strategies to allow engineers to adapt thermoset designs for thermoplastic manufacturing.

The shift from thermoset to thermoplastic composites is needed to meet the high manufacturing rate required for urban air mobility (UAM) vehicles. The manufacturing rate of thermoset composites are increased through parallel manufacturing lines due to the long cure cycle of thermoset material. The consolidation cycle for thermoplastic composites is significantly shorter than a thermoset cure cycle, therefore, the manufacturing rate for thermoplastics can be increased without the need for multiple manufacturing lines. Another advantage in favor of thermoplastics is the capability to remelt and reconsolidate the polymer without negatively impacting its mechanical properties. The latter opens the opportunity to use fusion joining methodologies to assemble structures without the need for fasteners or adhesive, and thus lower the structural weight of the part. Induction welding is the fusion joining methodology used in this investigation. Induction welding allows for localized heat generation in the thermoplastic composite without contact between the structure and induction coil, therefore, making it an ideal candidate to explore the fastener free assembly of thermoplastic propeller blade demonstrator.

The research presented in this thesis focuses on the transition from using a thermoset to thermoplastic composite for the manufacturing of a UAM propeller blade demonstrator. The transition process involves a reevaluation of the internal structure of the propeller blade, and creation of a manufacturing plan to laminate, consolidate, and fusion join the individual components of the propeller blade. The objective is to showcase different aspects one must consider when transitioning from a thermoset material system to a thermoplastic one. In addition, the application of induction welding highlighted to achieve a fastener-free assembly which can aid in increasing the manufacturing rate to meet high production rate required for UAM vehicles.

Rights

© 2022, Samuel Leonard Jones III

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