Phase Field Simulation Of Concrete Fracture Based On Abaqus

Fracture is the main mode of concrete material failure.Reliable and efficient concrete fracture models play an important role in the safety assessment of civil engineering structures,such as bridges,tunnels and dams.The research on concrete fracture,especially on crack initiation and propagation,has attracted more and more attention from scholars at home and abroad.The numerical simulation of concrete fracture,fracture theory and physical test verify and complement each other,and with the development of science and technology,the accuracy of concrete fracture simulation is constantly improved.The fracture phase field method,which is developed in recent years,can easily simulate the dynamic propagation process of cracks by automatically evolving the field variables to obtain the crack path.Therefore,the fracture phase field model based on Abaqus is adopted in this paper to simulate and analyze the concrete fracture problem and discuss the practical applicability of this model in engineering.Firstly,the energy functional of the fault phase field model is constructed,and two governing equations about the displacement and phase field variables were derived from the energy variational principle.Combined with finite element discretization,the stiffness matrix equation which could be solved numerically was obtained.Next,an interleaved iterative solution algorithm for the fracture phase field model based on Abaqus is established to solve the problems of visualization of calculation results,stiffness matrix sequencing and interleaved iterative solution.On this basis,the secondary development of fracture phase field model on Abaqus platform is realized.Then,the critical fracture surface energy threshold Gc in the fracture phase field model is determined from the fracture toughness,the phase field evolution equation without phase field gradient is substituted into the physical equation,and the value of the length scale parameter l0 in the fracture phase field model is determined from the critical fracture state.By simulating the uniaxial tensile bar,rectangular plate with single notch,three-point bending beam and rectangular plate with single notch with round hole,the results show that the interlaced iteration algorithm for the fracture phase field model has fewer iteration steps and faster convergence speed.When the mesh size is small enough,the crack width is a physical quantity independent of the mesh size and controlled by the length scale parameter l0.When the mesh size and loading step size are small enough,the crack propagation length is independent of the mesh size and loading step size.Choosing the appropriate mesh size and loading step length can improve calculation efficiency and save calculation costs.The crack propagation direction decreases linearly with the increase of displacement load direction.The feasibility and accuracy of the concrete fracture phase field method based on Abaqus are proved by the above results.Finally,the numerical simulation of the fracture phase field model of the 3D reinforced concrete beams strengthened by embedded prestressed CFRP is carried out,and the comparison between the model and the physical test is made.The results show that the fracture phase field model can well simulate the crack path and fracture failure mode,which can provide a new analytical tool for numerical simulation of concrete fracture engineering problems.