Ask a Librarian

Threre are lots of ways to contact a librarian. Choose what works best for you.

HOURS TODAY

Closed

Reference Desk

CONTACT US BY PHONE

(802) 656-2022

Voice

(802) 503-1703

Text

MAKE AN APPOINTMENT OR EMAIL A QUESTION

Schedule an Appointment

Meet with a librarian or subject specialist for in-depth help.

Email a Librarian

Submit a question for reply by e-mail.

WANT TO TALK TO SOMEONE RIGHT AWAY?

Library Hours for Sunday, August 25th

All of the hours for today can be found below. We look forward to seeing you in the library.
HOURS TODAY
10:00 am - 10:00 pm
MAIN LIBRARY

SEE ALL LIBRARY HOURS
WITHIN HOWE LIBRARY

MapsClosed

Media ServicesClosed

Reference DeskClosed

Cyber Cafe (All Night Study)Closed

OTHER DEPARTMENTS

Special CollectionsClosed

Dana Medical Library9:00 am - 11:00 pm

Classroom Technology ServicesClosed

 

CATQuest

Search the UVM Libraries' collections

UVM Theses and Dissertations

Browse by Department
Format:
Online
Author:
Alghamdi, Saleh Jaman
Dept./Program:
Department of Civil and Environmental Engineering
Year:
2019
Degree:
Ph. D.
Abstract:
Nacre, a natural composite consisting of biogenic aragonite and protein, possesses superior strength and toughness compared to its brittle aragonite components. In this work, we first show that dry nacreous sections exhibit complete brittle fracture along the tablet interfaces at the proportional limit under pure shear of torsion. We quantitatively separate the initial tablet sliding primarily resisted by nanoscale aragonite pillars from the following sliding resisted by various microscale toughening mechanisms. In addition, we use the pure shear of torsion to demonstrate how hydrated nacre resists the initial tablet sliding by tuning its nanoscale toughening mechanisms. In hydrated nacre, hydrogen bonds between water molecules and organic matrices provide temporal paths for stress redistributions, through which the shear resistance is gradually transferred from mineral bridges to contacted nanoasperities. In the subsequent sliding, dynamical interactions between nacreous tablets enable substantial plasticity before the catastrophic failure of hydrated nacre. Microscale growth layers between nacreous tables possess distinctive aragonite structures, including columns, spherulites and organic matrices. High temporal resolution experiments were performed to elucidate the tensile and shear behavior of growth layers under dry and hydrated conditions. Hydrated growth layers exhibited lower strengths and larger failure strain than hydrated nacre under both shear and tensile loadings. However, they successfully confined or deflected cracks within themselves when failure happened.
Note:
Access to this item embargoed until 04/15/2021.