Giri, Ashutosh
(2012)
Molecular Dynamics Simulations of the Mechanical Deformation of Nanoporous Gold.
Master's Thesis, University of Pittsburgh.
(Unpublished)
Abstract
Nanoporous (np) materials are a class of high strength and low density materials that have unique mechanical, chemical and physical characteristics that accompany them due to the size effect and high surface-area to volume ratio. Their mechanical properties play a vital role in many of their applications such as actuators, sensors and energy absorbers. In this work, the mechanical deformation behavior of np-Au under tensile and compressive stresses was studied by molecular dynamics simulations. The models representing np-Au were generated to capture the morphological features of np metals that have been processed via dealloying techniques. From the results of the simulations, it was found that these materials are brittle under uniaxial tensile loading and are very ductile under compressive loading. The engineering stress-strain relationship suggests that they have characteristic high yield strength and that these unique materials may even be stronger than bulk Au and also have the advantage of being highly porous. The macroscopic brittleness of np-Au presents a problem for useful application of these materials, but the microstructural features can be tailored to reduce the catastrophic failure. Under compression, their deformation behavior is similar to that of the Gibson and Ashby cubic unit cell model where cell wall bending is predicted to be the main deformation mechanism. One important difference between the predicted behavior according to the Gibson and Ashby model and the behavior observed from the atomistic simulations is that for the latter there is considerable strain hardening before foam densification occurs. By examining the crystallographic defects, the strain hardening behavior has been attributed to defects in the crystal structure that accumulates at the joints.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
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| Date: |
4 June 2012 |
| Date Type: |
Publication |
| Defense Date: |
2 April 2012 |
| Approval Date: |
4 June 2012 |
| Submission Date: |
9 May 2012 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
62 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Swanson School of Engineering > Mechanical Engineering |
| Degree: |
MSME - Master of Science in Mechanical Engineering |
| Thesis Type: |
Master's Thesis |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Thesis |
| Date Deposited: |
04 Jun 2012 20:19 |
| Last Modified: |
15 Nov 2016 13:58 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/12130 |
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