Research On Crack Propagation Of Concrete Based On Fracture Mechanics And Extended Finite Element

As various internal and external factors make the concrete in the molding process in the initial defects such as porosity,crack.These initial defects finally could make the instability and failure of structures under the working state of the component development,extension.,It is very different to obtain results by conventional elastic-plastic mechanics and finite element method(fem)analysis of the problem for displacement or displacement function discontinuity.This paper will analysis structure with initial crack fracture by fracture mechanics and Extended finite element.The specific studies of the main work is following:Through Analyzing the elastic fracture mechanics and the use range of elastic-plastic fracture mechanics,it's Target to deduce the numerical simulation calculation of stress intensity factor K and J integral and fracture Angle.Then introduce the level set function could be used to track the path of crack.Robustness is being proved in three-dimensional state of calculating crack front parameter by Abaqus from comparing with analytical solutions of fracture mechanics and calculation in Abaqus.The cohesive crack model was used to analyze the concrete fracture process zone.A new kind of softening is put forward after retrospect of the classic crack front after fracture process zone softening relationship research,which was used to analysis ?crack propagation simulation and modelling of ?,? mixed crack extension of plain concrete beam with initial crack.It is concluded that using optimization of a new type of softening curve than using double linear softening curve simulation results closer to the experimental value through simulating the force-displacement results compared with double linear and the experimental results.Concrete gravity dam with the initial crack quantitatively calculate static crack stress intensity factor of crack front,the J integral and the crack Angle and qualitatively simulate the path of crack extension,at last.To ensure the scientific nature of the fracture energy value,introducing the Xu ShiLang improved bilinear softening curve according to the existing material parameters can solve the fracture energy value and analysis the numerical simulation results.