Research On Fracture Performance Of Corroded Steel Plate With Central Crack

With the progress of national modernization construction and the continuous development of the field of construction technology,steel structures have been widely used because of their own advantages,and the resulting durability problems of steel structures have aroused constant attention.Since the steel structure in service is exposed to the air,the rust problem and its own crack defects are inevitable,which leads to the severe degradation of the fracture performance of the steel structure components,accelerates the instability of the cracks on the surface of the component,and leads to the destruction of the component,affecting the safety of the structure.In this paper,the steel structure materials with initial cracks are based on the macro-fracture mechanics theory.Taking the steel slag aisle beam used for many years in the industrial environment as the research object,the method of combining experimental discussion,theoretical analysis and numerical simulation is adopted to discuss.In this paper,the main research work is as follows:(1)Using the Q235 steel specimens with different degrees of corrosion,the basic performance test of monotonic tension was carried out,and the load-displacement curve,ultimate strength,fracture strength and other mechanical performance indexes of each specimen were obtained from the beginning to the stage of fracture.The monotonic tensile test is performed on the standard test piece,and the constitutive relationship of the material is obtained by fitting the curve of the plastic region through the transformation of the nominal stress-strain relationship and the true stress-plastic strain relationship.(2)Based on the three-dimensionally scanned surface topography data,the ABAQUS finite element software was used to reconstruct the tensile specimen,and the finite element model of the tensile specimen was simulated,and the accuracy of the simulation was verified by comparing the test results.Finite element calculation and analysis obtained the fracture parameters of the crack tip of each specimen at different stages,that is,the stress intensity factor K and J-integral,and the residual fracture toughness of the material was determined by the J-integral and the mechanical properties of the tensile specimen to establish the residual fracture toughness Degree of degradation model with respect to the characteristic parameters of corrosion.(3)Aiming at the influence of the degree of corrosion around the crack tip and the working conditions,using ABAQUS finite element software,the monotonous tensile numerical simulation of the uniform corrosion and pitting crack body members is carried out to deeply study the different corrosion characteristic parameters and mechanical performance indexes at the crack tip The impact on the degradation of steel fracture performance.By analyzing the fracture parameters of the stress field and strain field strength of the crack tip,the residual fracture toughness of different corrosion models is calculated,and the fracture criterion is established.The degradation models and rules of corrosion parameters such as cross-sectional area are compared,and the effects of pitting damage parameters on the degradation of the fracture performance of the corrosion specimen are compared.