The Coupling Method Of Analysis Structural Damage Under The Service Environment

To consider the damage evolution of structure under service environment, due to the synergy of the stress and the environmental factors, the damage evolution of structure is caused by the materials metallurgy, chemical and electrochemical environment factors and the stress of material or component status and historical factors which interact with each other. For the complex process of damage evolution, it is consisted of four parts which is the action of the corrosion damage nucleation under the environment, micro cracks initiation and propagation, propagation of the structure macroscopic crack and instability.In order to study the damage evolution of structure under service environment, the finite element method and the molecular dynamics were used to study the damage evolution of structure. At first, the stress and strain values were obtained by finite element method (FEM), and the strain surrounding corrosion area can be used as boundary condition to simulate the process of crack initiation for corrosion damage of different time around the location of the atoms and the corresponding energy diagram. At last, the size of the atomic coordinates corresponds to the crack initiation are input to the whole finite element model, and realize the across scales coupling analysis of the structure from micro to macro. The main works have been finished as following:(1) Review the domestic and foreign structural damage analysis method, its research status of the structural damage analysis method which is widely used.(2) The finite element analysis has been finished for the overall structure of including corrosion damage, and get strain values of the nodes around structure surface corrosion damage, for corrosion damage crack initiation provides the initial boundary value.(3) After the finite element analysis, get atom’s strain values of surrounding corrosion damage, it will be as the initial conditions of molecular dynamics methods. Using molecular dynamics methods combined with the velocity VERLET algorithm, through the C language program to solve the inter-atomic potential and speed, Then for the corrosion damage of micro crack initiation and propagation is simulated, At last, when it extension to the macroscopical cracks, get the atomic coordinates.(4) When micro crack propagation to the macro crack, get the atomic coordinates, and put it into the finite element as the initial conditions, the method has been established for analysis the evolution of structure under service environment from micro to macro.