Type
Text
Type
Thesis
Advisor
Robert V. Kukta. | Korach, Chad S. | Kao, Imin
Date
2010-12-01
Keywords
buckling, Carbon Nanotube, compression, Nanoindentation, Raman, VACNT array | Mechanical Engineering -- Materials Science -- Nanotechnology
Department
Department of Mechanical Engineering
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/70954
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
The use of carbon nanotubes (CNTs) in the form of vertically aligned arrays or films has been of interest due to the super-compressible response and the ability to be used as electrical and thermal contacts. CNT arrays have shown the remarkable ability to react as foam-like structures and exhibit localized, coordinated buckling within specific regions. An understanding of the buckling region evolution and the resulting effects on the bulk CNT array response are important, unanswered fundamental questions necessary for the future application of CNT arrays. Here, we report on the low-cycle compression of bulk vertically aligned CNT arrays to observe initiation and growth of the buckling as a function of compressive strain and the contacting substrate material. A critical strain of ~5.5% is found above which the buckling region length increased and below which remained at or below the applied strain. The results are corroborated with nanoindentation on the surfaces, which indicate a stiffening of the near surface by 9.4%-16.5% with increasing applied strain. Also, contact substrates with different stiffness, lithium niobate and a polymer gel, were compared, which resulted in changes of ~32% in total array height after cyclic compression. Raman spectroscopy on CNT arrays before and after compressive deformation was performed observing repeatable vibrational shifts in the strained regions. Also, to observe the applicability of CNT arrays as contact sensors, electrical resistance change during compression was measured and found to increase by 4 times in the parallel versus vertical direction. Observation and results of the buckling region nature and relationship with applied strain and contacting substrates are important for applying the nanotube arrays to energy absorbing cushions, tunable dampers, thermal contacts, contact sensing, chemical sensing, or in sliding contact.
Recommended Citation
Cao, Changhong, "Measurement of Vertically Aligned Carbon Nanotube Array Compression Response" (2010). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 162.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/162