The Finite Element Numerical Analysis Of Mechanical Behavior Of Carbon Nanotube Reinforced Cement Composites

Carbon nanotubes(CNTs) have excellent mechanical properties, and have a wide application prospect as the reinforcement. The concrete is the most widely used materials in engineering, but the crack is the biggest problem affecting their application. Carbon nanotubes as reinforcement relative enhancement of cement-based materials is worth looking forward to. In this paper, carbon nanotube reinforced cement composites were studied by using numerical simulation methodIn order to research the effect of B, N ring doping on(5, 5) single-walled carbon nanotubes(SWNTs) and the effect of tension and compression deformations on adsorption properties between Al and single-walled carbon nanotubes by B(N) ring doping, through using plane wave pseudopotential method and generalized gradient approximation based upon the density functional theory, optimize the geometrical structures of the adsorption model of B(N) ring doped single walled carbon nanotubes and Al under no deformation, tension deformations and compression deformations. The formation energy of B(N) ring doped single walled carbon nanotubes were calculated. The adsorption energies and adsorption structure were calculated. By analyzing, the most stable adsorption position of Al atom is determined. The results revealed that B, N ring doped(5, 5) single-walled carbon nanotubes is stable and feasible. Meanwhile, B, N ring doping can increase adsorption energy between Al and single-walled carbon nanotubes. And within a certain range of tensile and compression deformations, most of adsorption energies between single-walled carbon nanotubes and Al with different positions can be reduced.The 3D random launch program of cylinder in the micro body is written by using APDL development function of ANSYS software. A model of carbon nanotube reinforced cement based composites was established. Carry out numerical simulation of uniaxial compression and tension of the material and analysis the section results of horizontal displacement, vertical displacement and horizontal stress, vertical stress and the first principal stress. It is found that the incorporation of carbon nanotubes has some effect on the change of the compression and tension of the cement matrix composites, but the effect is small. Near the particles, the stress distribution is not uniform, the stress concentration happens. In the stretching process, the stress of the side which is parallel to the loading direction is smaller, the stress of the side which is vertical to the loading direction is smaller to the loading direction is larger, and the stress within a certain range of matrix increase. The difference between the stress value of the reinforcement and the stress value of the cement matrix is relatively large. It can be concluded that, when the tensile failure occurs, crack initiation and extension may start from the edges of the side which is vertical to the loading direction.Study on a two-dimensional random distribution model of carbon nanotube reinforced cement matrix composites. Carry out finite element simulation calculation of composite materials by using the life and death element technology of ANSYS software. And analysis the initiation, propagation process of crack under multi load step. It is found that the connection between the reinforcement and the matrix is the most easy to crack in the composite materials, and crack propagation direction is vertical extension. Without considering the interface, the destruction of the matrix is the decisive influence on the damage of the composite material.In consideration of different interface strength, numerical simulation of single axis tensile failure process of carbon nanotube reinforced cement matrix composites was carried out. Low interfacial strength will lead to crack expand from the interface layer, and then extended to the matrix. When the load is too large, the interface will be completely destroyed. When the difference of interface strength and matrix strength is not big, the crack expands along the vertical direction with large matrix stress, the interface layer completely failure phenomenon does not appear.