Date of Graduation

12-2019

Document Type

Thesis

Degree Name

Bachelor of Science

Degree Level

Undergraduate

Department

Mechanical Engineering

Advisor/Mentor

Nair, Arun

Committee Member

Chen, Jingyi

Abstract

Emerging metallic composite materials implanted with graphene sheets are showing immense promise, with benefits being observed with regards to mechanical, thermal, and electrical material properties. This research aims to investigate the effects on ultrasonic wave propagation in Copper/Graphene Metal Matrix Composites (Cu/Gr MMCs) with varying graphene arrangements inspired from nacre and bone nanoscale material distributions. To accomplish this, the molecular dynamics (MD) method is utilized to simulate nanoscale wave propagation on a set of Cu/Gr MMCs with differing graphene arrangements and volume percentages ranging up to 4.56%. The computational model results are then analyzed to determine the variation in energy transmission through the set of MMCs and to observe changes in wave propagation patterns. The MD simulations concluded that the graphene arrangement does influence the nature of the propagating wave. It was also found that the volume percentage of graphene contributes more directly to the deviation in energy transmission rather than the graphene dispersion pattern, resulting in a linear relationship between energy transmitted and volume percentage. To test trends observed in MD simulations, ultrasonic experiments are conducted on 3D printed samples at the macroscale with varying volume percentages that mimic the MD models at the nanoscale. The ultrasonic experiments led to the conclusion that the highest amount of transmitted energy corresponds to the solid sample, similar to that observed in the single crystal copper during MD simulations. As the volume percentage changes in the 3D printed samples, the energy transmitted decreases by 17- 22%. Unlike the MD simulations, no overall trend was observed amongst the samples, however the bio-inspired samples did display a decreasing exponential trend of transmitted energy with an increase in volume percentage. Additional ultrasonic experiments with a larger sample set are necessary to validate/invalidate the trends observed in the MD simulations.

Keywords

Metal Matrix Composites; Computational Simulation; LAMMPS

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