Role of Mesoscopic Friction and Morphology in Large Deformation of Carbon Nanotube Network: a Distinct Element Method Study

Carbon nanotubes (CNTs) are game-changing materials in various disciplines, but the limited capability for simulating CNT in bulk represents a significant obstacle for realizing their promising applications. We address this challenge by developing a new simulation methodology titled the mesoscopic Distinct Element Method (mDEM). With parameters input from atomistic simulations, mDEM bridges across the atomistic and mesoscopic length scales, providing an efficient tool to predict the large deformation mechanism of CNT network. Validated through experiments, mDEM is utilized in hypothesis-driven research to demonstrate the internal structural evolution of CNT network stretched until fracture. At small and moderate deformations, zipping relaxations along the applied strain direction dictates the microstructural evolution. At larger deformations, the occurrence of energetic elasticity promotes yarn densification, by relaxing CNT waviness and eliminating squashed pores. Besides the strain-induced alignment process, phononic and polymeric friction promote CNT alignment by enabling load transfer. Our parametric studies not only offer guidance in manufacturing industry to achieve high quality yarn, but also potentially offer an effective way to model fibrous materials in general.