Document Type

Open Access Thesis

Embargo Period

9-1-2017

Degree Program

Mechanical Engineering

Degree Type

Master of Science (M.S.)

Year Degree Awarded

2016

Month Degree Awarded

September

Advisor Name

Jonghyun

Advisor Last Name

Lee

Co-advisor Name

Jonathan

Co-advisor Middle Initial

P

Co-advisor Last Name

Rothstein

Third Advisor Name

David

Third Advisor Middle Initial

P

Third Advisor Last Name

Schmidt

Abstract

Abstract

The cold spray process is an additive manufacturing technology primarily suited for ductile metals, and mainly utilized in coating surfaces, manufacturing of freeform parts and repair of damaged components. The process involves acceleration of solid micro-particles in a supersonic gas flow and coating build-up by bonding upon high velocity impact onto a substrate. Coating deposition relies on the kinetic energy of the particles. The main objective of this study was to investigate the mechanics of polymer cold spray process and deformation behavior of polymers to improve technological implementation of the process.

A finite element model was created to simulate metal particle impact for copper and aluminum. These results were compared to the numerical and experimental results found in the literature to validate the model. This model was then extended to cover a wide range of impact conditions, in order to reveal the governing mechanisms of particle impact and rebound during cold spray.

A systematic analysis of a single high-density polyethylene particle impacting on a semi-infinite high density polyethylene substrate was carried out for initial velocities ranging between 150m/s and 250m/s by using the finite element analysis software ABAQUS. A series of numerical simulations were performed to study the effect of a number of key parameters on the particle impact dynamics. These key parameters include: particle impact velocity, particle temperature, particle diameter, and particle density, composition of the polyethylene particle, surface composition and the thickness of a polyethylene film on a hard metal substrate. The effect of these parameter variations were quantified by tracking the particle temperature, deformation, plastic strain and rebound kinetic energy. The variation of these parameters helped define a window of deposition where the particle is mostly likely to adhere to the substrate.

First Advisor

Jonghyun Lee

Second Advisor

Jonathan P Rothstein

Third Advisor

David P Schmidt

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