Date Approved

6-28-2024

Embargo Period

6-28-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Mechanical Engineering

College

Henry M. Rowan College of Engineering

Advisor

Behrad Koohbor, Ph.D.

Keywords

Cold Spray;Composite;Damage;Impact;Polymer;Repair

Disciplines

Engineering | Materials Science and Engineering | Mechanical Engineering

Abstract

Fiber-reinforced polymer composites are widely used in industries and applications such as energy, automotive, defense, and aerospace. This study investigates the application of polymer cold spray, an emerging additive manufacturing process, for coating and repair of fiber-reinforced polymer (FRP) composites. The research starts with feasibility studies focused on the cold spray deposition of thermoplastic nylon-6 particles on woven glass fiber-reinforced composites (GFRP). A parametric study determines critical process parameters window, ensuring successful deposition and bonding without compromising the macroscale mechanical behavior. These findings indicate that the cold spray process does not adversely affect the fiber integrity or surface quality of the composites. Advancing from coating to repair, we explore polymer cold spray as a rapid method to repair and restore the mechanical properties of damaged GFRP composites. We assess the effect of impact energy on mechanical properties of GFRP panels and use a variety of powder materials for repair, including thermoplastics, thermosetting materials, and novel fiber-reinforced composite powders. Notably, when the damage was confined to the surface and near-surface levels, repairs by fiber-reinforced thermoset powder feedstock exhibits superior mechanical performance and improved recovery. This finding underscores the potential of fiber-reinforced thermoset powders in enhancing the durability and longevity for repairing the damaged composite materials.

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Available for download on Sunday, June 28, 2026

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