Modeling the auxetic transition for carbon nanotube sheets

Abstract

A simple model is developed to predict the complex mechanical properties of carbon nanotube sheets (buckypaper) [Hall et al., Science 320 504 (2008)]. Fabricated using a similar method to that deployed for making writing paper, these buckypapers can have in-plane Poisson's ratios changed from positive to negative, becoming auxetic, as multiwalled carbon nanotubes are increasingly mixed with single-walled carbon nanotubes. Essential structural features of the buckypapers are incorporated into the model: isotropic in-plane mechanical properties, nanotubes preferentially oriented in the sheet plane, and freedom to undergo stress-induced elongation by both angle and length changes. The expressions derived for the Poisson's ratios enabled quantitative prediction of both observed properties and remarkable new properties obtainable by structural modification.

Inducing out‐of‐plane auxetic behavior in needle‐punched nonwovens

“…These researchers also experimentally found a large negative Poisson's ratio for stainless steel mats composed of fused nanowires which had been treated by a compression‐sintering protocol . Baughman et al found that the in‐plane Poisson's ratio for buckypaper changes from positive to negative on increasing the ratio of multi‐walled carbon nanotubes to single‐walled nanotubes. Commonly encountered cellulose‐fiber based paper, too, has been reported to increase in thickness when strained in tension .…”

Analysis of Auxetic Beams as Resonant Frequency Biosensors

“…Auxetic materials are solids that possess negative Poisson's ratio, and have been investigated for practical applications including fasteners, 25 arterial prostheses, 26 intervertebral disc, 27 drug releasing stents 28 and other prostheses, 29 cushions, 30,31 molecular lters, 32À35 antivibration glove, 36 novel textiles, 37 shoes for diabetic patients, 38 pressure vessels 39 and other thin-walled structures, 40 and shock absorbers. 41,42 It is of interest to note that although carbon nanotubes have been used as nanocantilever T.-C. Lim sensors and that auxetic nanotubes been investigated in recent years by Scarpa et al, 43 Yao et al; 44 and Coluci et al; 45 auxetic nanotubes have so far not being adopted as nanocantilevers for sensors. Further information on auxetic materials are available from Greaves et al, 46 and Evans and Lakes.…”

Dynamic response of sandwich panels with auxetic cores

“…Auxetic behavior could occur in some materials built of carbon nanotubes and in these cases, the value of Poisson's ratio varies in the range from +0.06 to −0.2 . The most recent research concerning microstructural materials indicates an auxetic behavior in graphene‐based structures.…”