The Homogenization Finite Element Simulation On Coating Honeycomb Structure And Fiber-reinforced Composites

As an important porous material, honeycomb materials have been widely used in many fields because of their excellent mechanical properties. However, the disadvantage of the traditional honeycomb materials limits their wide application. In order to overcome the shortage, the coating is added to the honeycomb surfaces for improving the mechanical properties of traditional honeycomb materials here. In addition, the physical and mechanical properties of composites depend on not only properties of their constituents and the corresponding structure but also the interfacial properties, so the influence of interfacial properties on the macroscopically effective properties of fiber-reinforced composites is firstly investigated in this study, which will provide a computational approach for the further study on the interfacial effect of the honeycomb materials with coating surfaces. The following conclusions can be drawn from the present study:(1) A three-dimensional(3D) representative volume element(RVE) model is developed by using the computational homogenization finite element method. The corresponding user subroutine and Python programs are coded.(2) Square, triangular, circular and hexagonal RVE models are modeled, and then their effective elastic parameters are predicted using the proposed homogenization finite element method, respectively. The numerical results show that the in-plane shear properties of the regular hexagon honeycomb are the best.(3) The effective of elastic parameters of the hexagonal honeycomb with coating surfaces are numerically predicted via the proposed approach, and are also compared to those obtained from the analytical method. It can be seen from the study that the simulated results show good agreement with the theoretical results. The numerical and theoretical results also indicate that both of the in-plane and longitudinal elastic moduli increase with the increase of the coating thickness, and they will exceed the elastic modulus of the honeycomb wall as the coating thickness reaches a certain value.(4) A 3D RVE model of fiber-reinforced composites(FRCs) is developed using both periodic and homogeneous boundary conditions. The macroscopic elastic constants of FRCs are numerically predicted, and are compared to those obtained from the theoretical models. The proposed model has been validated with the theoretical results for the composites with perfect bonding between the fiber and the matrix. The imperfect interfaces between the fiber and the matrix are taken into account by introducing cohesive contact surfaces. The influences of the interface on the elastic constants and the tensile strengths are examined using the interfacial model. In contrast the interfacial strength, the interfacial stiffness and fracture energy can significantly influence the transverse tensile strength of the composites, while the longitudinal tensile strength of the composites is almost independent on the interfacial properties, and it increases sharply with an increase in the fiber volume fraction.