Date of Award

Spring 5-6-2022

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Advisor

Roberto Lopez-Anido

Second Committee Member

Senthil Vel

Third Committee Member

Keith Berube

Additional Committee Members

Robert Hart

Abstract

Continuous fiber reinforced thermoplastic (CFRTP) composites have been proposed as an alternative to metals in structural applications. CFRTP composites can be used to create structures that are lighter weight, have better resistance to environmental factors, and have the potential to be recycled. However, one of the main challenges to CFRTP composites is connections between structural members. The goal of this thesis is to investigate the feasibility of joining CFRTP composites to both similar and dissimilar materials through literature review, coupon testing, design of a structural joint, and a small scale laboratory prototype of the joint. To achieve this goal the following steps were implemented.

1) Conduct a literature review to determine the state of the art in joining methods, optimal thermoplastic materials to use, and appropriate computer modeling techniques for joints.

2) Perform coupon level testing to obtain standard mechanical properties of the thermoplastic materials, and to characterize material joining methods.

3) Design a structural CFRTP composite joint.

4) Test a small scale prototype of the joint for design validation.

Two joining methods were selected to be examine: adhesive bonding and mechanical fastening. Carbon fiber-Polyphenylene sulfide (PPS) unidirectional composite tape was selected to consolidate plates with quasi-isotropic layups. Lap shear joints were examined using experimental evaluations. The experiments serve to characterize the mechanical properties required for structural design using the proposed joining methods: adhesive bonding strength and fastener bearing strength. In addition, a comprehensive program of standard tests for material characterization of the CFRTP composite were conducted to generate properties for structural analysis. A structural model of a connection in a bridging structure was developed using finite element analysis. Lastly, a prototype of the joint was constructed and tested.

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