Multiscale Numerical Simulation Of Concrete Based On Extended Finite Element Method

In the current engineering construction,the application of reinforced concrete structure is very extensive,and the concrete material occupies a large proportion in this kind of structure.Therefore,concrete has a great influence on the safety and durability of structures.Concrete materials have very complex mechanical properties and size effects.So far,many problems of concrete have not been well solved,so the study of concrete materials is very necessary and significant.Concrete is a kind of composite material made of mortar and aggregate.From the macroscopic scale,it is regarded as isotropic homogeneous material.This ignores the inhomogeneity inside the concrete and a large number of meso cracks.These meso cracks mainly exist at the bond between aggregate and mortar,and will develop across scales during the normal service life of concrete and structure.In the course of damage evolution,cracks propagate from meso scale to macro scale,which results in failure of concrete and structure.Based on the Monte-Carlo random sampling method,this paper analyzes the shape and geometry information of the aggregate inside the concrete at the mesoscopic level.and establish a random aggregate model of concrete with different aggregate distribution.In this paper,numerical simulation of uniaxial tension of numerical concrete is carried out by ABAQUS finite element analysis software.The simulation results can reflect the stress and strain characteristics of concrete under the corresponding stress state,and reflect the damage and failure process of concrete.The extended finite element method(XFEM)is based on the idea of the unit decomposition method.In the traditional finite element framework,the discontinuous function reflecting the crack surface is added in the displacement field,and the asymptotic displacement field function of the crack tip is also increased.It reflects the existence of the crack and makes the crack and the finite element model independent of each other,so that it is convenient for the simulation of crack propagation.The multi-scale finite element analysis of structure combines the high computational efficiency of the rough element with the fine element with high computational accuracy in the same numerical model.In this way,it guarantees that the calculation accuracy is sufficient and the computational efficiency of the structure is improved.This method has broad prospects in engineering applications,and it is a very difficult subject.Therefore,we should pay attention to and study it.In this paper,the finite element analysis software ABAQUS is used to accomplish the coupling of the rough element and the fine element,and a multi-scale numerical analysis model of the reinforced concrete column is established.At the same time,combined with the extended finite element method,the multi-scale analysis model can effectively simulate the cracking process and failure modes of reinforced concrete columns under different axial and horizontal loads.