Multiscale Modeling Of The Mechanical Properties Of The Carbon Nanotube-reinforced Composites

Carbon nanotubes (CNT) polymer nanocomposites was thought to be a vast application prospect of research topics, which was a result of the unique properties of reinforced phase. Due to these kind of materials with typical multi-scale structural characteristics, the traditional finite element method was difficult to predict the mechanical behavior and mechanical properties, so the effective multi-scale mechanics model and algorithm was currently a hot topic in this research field.With the rapid development of computer hardware and software technology, the multi-scale numerical simulation had been gradually used in the prediction and analysis of the nanocomposites, which is not only a beneficial supplement of experimental research, but also an expansion for predicting the mechanical behavior of the nano-materials. In order to accurately predict the mechanical behavior and properties of polymer composites, it needed to more clearly understand of the nano-structure of this kind of material. Then, the strategy of multi-scale modeling and simulation research were established in order to realize the seamless connection between the different space and time scales. In this paper, we combined with molecular dynamics, mesoscopic mechanics and macro finite element numerical simulation technology to study the mechanical properties of carbon nanotube/polymer composites, which provided reference data for the design and processing of materials.1. With the help of the simulation software LAMMPS about the molecular dynamics, single-walled carbon nanotubes/epoxy resin composites was simulated, and then we got the information of atomic structure. With the equal energy and the aid of APDL computer language, we simulated the atomistic structure into a continuous structure, namely the representative volume element (RVE).Finally we had simulated the RVE into an equivalent fiber (RF) through equal strain energy, and then got the elastic modulus of RF. The results by molecular dynamics with atomic-based continuum were close to the results by Wernik et al. so this method is feasible.2. With the help of the simulation software MATERIALS STUDIO, we built the SWNT/polyethylene (PE) composites model and calculated the atomic agency. Then, we applied the RVE into a fiber by the atomic-based continuum (ABC) and APDL computer language, and got its modulus of C11, EL, GT, GT, KT.3. With the help of the simulation software DIGIMAT, the equivalent mechanical model was established, and the carbon nanotubes distributed in the PE matrix randomly. Mesoscopic mechanics and finite element method were used respectively to calculate and analyze the mechanical properties of the CNT/PE composite when the volume percentage of carbon nanotube was 0.1%,0.2% and 0.3%. The results by FEM were close to the results by MORI-TANAKA method, but it was less than the results by MORI-TANAKA method. The reason was that MORI-TANAKA had the ideal assumptions, but the FEM of mesoscopic mechanics don't take into account the ideal assumptions.