13th International Conference on Fracture June 16–21, 2013, Beijing, China -1- Tunable Negative Poisson’s Ratio of 3D Spanned-Fullerene Nanotube Nanotruss Jianyang Wu1, Jianying He1, Zhiliang Zhang1,* 1Department of Structural Engineering, NTNU Nanomechanical Lab, Norwegian University of Science and Technology (NTNU), Trondheim N–7491, Norway * Corresponding author: zhiliang.zhang@ntnu.no Abstract CNT-based network, as an emerging class of material, attracts extensive research interest in recent years from both the scientific community and industry. In this study we proposed novel covalently bonded bcc-lattice like 3D nanotruss made up of fullerenes spanned by CNTs. The mechanical properties of such architecture are systematically investigated via full atomistic simulation. Our simulations reveal that the CNTs length of the 3D nanotruss plays a significant role on the mechanical properties. This nanotruss network displays orientation dependent deformation behaviour. Under <100> direction tension, negative Poisson’s ratio is observed exclusively for the case of N = 0, while a “flipping” behaviour of Poisson’s ratio with “Negative → Positive → Negative” appears when the tension is applied along <110> direction. The findings in our work would provide guidance to optimal design of CNT-fullerene based structures towards tailor-made properties. Keywords Single-walled carbon nanotubes, Fullerene, Nanotruss, Negative Poisson’s ratio, Atomistic simulation 1. Introduction Since their discovery [1, 2], the properties of fullerenes and nanotubes have been extensively studied both by experiment and by simulation. It is found that they, as unique zero-/one-dimensional carbon materials, possess predominant physical, chemical, and mechanical properties combined with a very little weight. To fully exploit their unique properties and explore additional properties, various types of carbon architectures made up of fullerenes and carbon nanotubes (CNTs) have been successfully fabricated and investigated. A hybrid carbon nanostructure termed “nanopeapod” fullerenes are encapsulated in CNTs, has been fabricated, and the nanopeapod exhibits a variety of intriguing physical and chemical properties [3-6]. Another nanostructure based on fullerenes and CNTs called “nanobuds” holds exceptional field emission properties [7]. A Y-shaped CNT junction displays rectifying and electrical switching properties, such that it can serve as a switching device [8]. Moreover, organized 2D and 3D CNT architectures can be fabricated to realize specific functional properties for a variety of meso- and macro-scale engineering applications. Hall et al. [9] revealed that the CNT networks can exhibit unusual mechanical properties such as negative Poisson’s ratio. By infiltrating a polymer into a reticulate CNT (RCNT) architecture, CNT-network-based reinforced composites are formed to achieve superior mechanical properties [10], originating from strong molecular-level coupling between reticulate CNTs and polymer chains. The RCNTs/polydimethylsioxane with high transparency, high conductivity, and excellent stretchability in addition to the facile fabrication, is a promising candidate as interconnects and electrodes for stretchable intelligent and functional devices [11]. Covalently bonded 3D CNT networks have also been produced at large scale [12], in which an effective stress distribution in the network improves the mechanical strength of the materials. Computer-aided design and simulation of 2D and 3D nanostructures consisting of fragments of CNTs-junctions also helps to exploit their potentials [13-20]. For example, Romo-Herrera et al. [14] showed that 2D and 3D systems can be utilized for complex integrated nanoelectronic circuits due to specific paths of charges flowing through the nodes of the systems, and the 3D super-cubic and super-diamond architectures have the ability of supporting extremely high unidirectional stress. Despite the increasing interest in CNT architectures,
RkJQdWJsaXNoZXIy MjM0NDE=