Finite Element Analysis Of Mechanical Properties Of Carbon Nanotubes Reinforced Concrete Composites

Concrete is the most widely used building material.Due to the shortcomings of concrete materials such as low tensile strength,poor deformation capacity and heavy deadweight,various cracks are generated in the use of concrete structures,thus affecting the strength of the entire building structure.Carbon nanotube is one of the materials with the best mechanical properties that we found so far.Its excellent properties also strongly support the research on the application of carbon nanotube material into the concrete.Carbon nanotube,as nanomaterial that filled micropores in concrete composites,has the effect of strengthening and toughening the structure.Incorporating a small number of carbon nanotubes into concrete can significantly improve the strength,toughness and durability of concrete.In this paper,Material Studio and ANSYS software are used to simulate the interface bonding strength,interface stress distribution,macroscopic elastic modulus and self-sensing performance of carbon nanotube reinforced concrete composites.The details are as follows:(1)Material Studio software was used to establish the carbon nanotube model and the model of carbon nanotubes adsorbing major macromolecules in concrete material.Dmol3 module was used for simulation calculation to calculate the adsorption energy between the carbon nanotube and the molecule,and the adsorption energy of the model under the action of tension and compression.The results show that the adsorption energy of carbon nanotubes to each molecule is positive,indicating that the contact surface between carbon nanotubes and each molecule is good,that is,the interface bonding strength between carbon nanotubes and concrete is high.(2)The APDL command stream in the finite element simulation software,ANSYS,was used to establish the three-dimensional random distribution carbon nanotube reinforced concrete composites models,simulates the carbon nanotubes reinforced concrete composite under tensile compression deformation of von Mises stress and the first principal stress distribution,as well as carbon nanotubes and matrix interface normal stress and shear stress distribution.The results show that the carbon nanotubes bear large von Mises stress and the first principal stress,and play a reinforcing role in the composites.The stress value of the upper part of the matrix is relatively large,while the stress value of the lower part is relatively small.(3)The carbon nanotube reinforced concrete composites models with different aspect ratios and different volume percentages were established using ANSYS software to predict the elastic modulus.The results show that the influence of length to diameter ratio on the modulus of elasticity increases with the increase of the volume percentage of carbon nanotubes.The elastic modulus of composites increases with the increase of volume fraction.(4)ANSYS software was used to simulate the inner force and stress cloud diagram of shield tunnel sheet.The stress cloud diagram of carbon nanotube concrete composite as a sensor in shield tunnel is simulated.The results show that the waist,the top and the bottom of the shield tunnel are the most vulnerable to damage.The upper and lower part of the sensor and the interface of the shield slice are most prone to plastic deformation,fracture and debonding.