3D-Numeriacl Simulation Of Nonlinear Crack Propagation In Concrete Beams

Concrete is a kind of complicated heterogeneous material, The technique of numerical simulation of it's fracture can help us know better about different kinds of mechanism in the destructive process, and help to explain some phenomenons of rupture occured in the experiments. When this technique is proved reliable and effective, It can replace some experiments, saving a lot of human and financial resources. More importantly, the experimental technology to simulate the complicated border and load conditions, the scale model tests in a variety of similar rate to meet the issues, using numerical simulation is expected to be the better solution.. Therefore the research in this field is of great value both in theory and works. This paper presents a there dimensional energy-based approach for the finite element modeling of nonlinear crack fracture, and completed parts of the 3-D nonlinear finite element software's development(based on the 2-D nonlinear finite element software which is already available).A detailed summary and elaboration of four key features that a successful FEM must have is firstly presented: a proper constitutive model for concrete tensile softening behaviour,a proper crack propagation criterion, an efficient remeshing procedure with an accurate mesh-mapping technique to transfer structural responses of an old FE mesh to a new one, and a robust and efficient numerical solution technique to solve nonlinear equation systems characterised with snap-through or snap-back.Among the four key features showed above ,the proper crack propagation criterion is the core part. Energy-based criterion is accepted by many scholars because of its fast convergence rate of energy entities in FE analysis and its accuracy even using coarse meshes. But mostly it use two dimension methods, this paper presented a 3D-VCE(virtual crack extension) technique model and 3D numerical energy criterion which can be easily implemented on computer.In the procedure of developing 3D nonlinear finite element program ,an analysis of the basic 3D finite element unit was first carried out, and the degradation technology was used to deal with the special element. The development of the whole program is a huge and complex work, this paper completed parts of it and showed the idea of numerical simulation by a dynamic display of a concrete beam's fracture process.This paper did a certain initial accumulation in the research of 3D numerical simulation of the nonlinear fracture in concrete beams, and be part of the National Natural Science Foundation project research《Fully automatic modeling of High arch dam's fracture using cohesive discrete crack model and its safety evaluation》.