Modeling and analysis of CNT wires subjected to external tensile loads

Abstract

Carbon nanotubes (CNTs) have been processed to yarns/wires/strands, as well as woven, non-woven and braided textiles via textile technologies, aiming to utilize their remarkable mechanical, electrical and thermal properties at micro/macro scales. Since CNT yarns/wires are the fundamental units of many structures, their mechanical properties, such as tensile modulus and strength, are crucial factors to determine the mechanical performance of such textiles under different conditions. This study develops a suitable model to predict the tensile strengths of CNT wires based on their twisting condition with the number of CNT yarn configuration. Femap finite element analysis software was used as a modeling tool while Automatic Dynamic Incremental Nonlinear Analysis (ADINA) software was used as a solver of advanced non-linear analysis (SOL 601) for twisted CNT wires consisting of 31 yarns. The numerical model was used to simulate CNT yarns interactions with each other, and 18.23%, 17.08%, and 16.02% strain cases were utilized to compare the experimental test results. It was observed that helix angles reduced to 12.4° on 18.23% strain case, whereas numerical model result showed 6° reduction on helix angles. Similar results were observed on 17.08% and 16.02% strain cases. Test data showed about 10.4° helix angle reduction for 17.08% strain and 9.4° helix angle reduction for 16.02% strain cases, whereas the numerical model produced 4.7° and 3.9° reductions for 17.08% and 16.02% strain cases, respectively. These variations may be because of the no-uniformity of CNT wires, local plastic deformations and sliding of individual CNTs in the yarns. Several small models were created using equivalent properties and analysis setup to ensure that models are converging prior to running the model of 31 yarn CNT twisted wires.