Simulation analysis on mechanical property characterization of carbon nanotubes reinforced epoxy composites

Carbon nanotube (CNT)-reinforced composites have ultra-high elastic moduli, low densities, and fibrous structures. This paper presents the multi-scale finite element modeling of CNT-reinforced polymer composites from micro- to macro-scales. The nanocomposites were modeled using representative volume elements (RVEs), and finite element code was written to simulate the modeling and loading procedure and obtain equivalent mechanical properties of the RVEs with various volume fractions of CNTs, which can be used directly in the follow-up simulation studies on the macroscopic model of CNT-reinforced nanocomposites. When using the programming to simulate the deformation and fracture process of the CNT-reinforced epoxy composites, the mechanical parameters and stress-strain curves of the composites on the macro-scale were obtained by endowing the elements of the lattice models with RVE parameters. Tensile experiments of the CNT-reinforced composites were also carried out. The validity of the finite element simulation method was verified by comparing the results of the simulations and experiments. Finite element models of functionally graded CNT-reinforced composites (FG-CNTRC) with different distributions were established, and the tensile and three-point-bending conditions for various graded material models were simulated by the methods of lattice model and birth-death element to obtain the tensile and bending parameters. In addition, the influence of the distribution and volume ratio of the CNTs on the performance of the graded composite material structures was also analyzed.