The research on the mechanical properties of cast steel itself includes the research on the mechanical properties of cast steel joint components and the research on the mechanical properties of cast steel materials. The performance of cast steel joints includes static performance and fatigue performance. In terms of static performance of cast steel joints, a lot of research has been carried out at home and abroad, and rich results have been obtained.
Zhao Caiqi and Ma Jun of Southeast University combined with the cast steel joint of Nantong Sports Convention and Exhibition Center, carried out the experimental research on the cast steel joint under spatial stress state, carried out the nonlinear finite element analysis of the cast steel joint by using ANSYS, and obtained the stress distribution law of the cast steel joint; Guo Zhengxing, Shu Ganping, Southeast University, the new museum of Suzhou Museum, Nanjing
Finite element analysis, full-scale or scale test analysis of special-shaped cast steel joints in a series of engineering projects such as Hexi jin’ao building and Nanjing Huaxin city tower have been carried out, and some engineering experience has been accumulated.
Through full-scale model test and finite element analysis of Y-type cast steel joints in Nanchang West Railway Station, Wang Menglei, a graduate student of Hefei University of technology, obtained the mechanical properties of cast steel joints under bidirectional bending moment and axial force. The safety and reliability of Y-joint of Nanchang west railway station are evaluated by comparing the experimental research and the calculation results with the finite element method. In addition, the corresponding cast steel joints are studied experimentally or numerically through different engineering examples, and the application design specification of cast steel joints is also formulated in China.
In the research of fatigue mechanical properties of cast steel joints, some achievements have been made at home and abroad. J. V. shape et al. Pointed out that the welding repair technology used to repair casting defects will not weaken the fatigue strength of steel castings, and suggested using the finite element method to calculate the location and size of SCF (stress concentration factor); The fatigue test of a typical X-joint shows that the fatigue crack originates from the casting defect on the inner wall surface of the steel casting.
DNV (DET Norske Veritas, DET Norske Veritas) design guidelines recommend the use of finite element method to analyze the stress distribution and maximum SCF of steel castings. The reciprocal of the slope of S-N curve used by steel castings is 32 million times, and the fatigue strength corresponding to service life (125 MPa). The fatigue numerical analysis of cast steel joints in sightseeing tower of Hangzhou Bay sea crossing bridge project sea platform reconstruction project, which is in the charge of Jin Hui of Southeast University, has carried out the fatigue numerical analysis of cast steel joints in sightseeing tower of Hangzhou Bay sea crossing bridge.
Chen Haizhou of Tongji University studied the cast steel joint in the sightseeing tower of Hangzhou Bay sea crossing bridge in China. Through the static load test and bending fatigue test of two scaled models of cast steel joint, an approximate S-N curve of the cast steel joint was obtained. Based on the workbench in ANSYS, Sun Yun of Henan University carried out the fatigue analysis of a typical cast steel bifurcated joint under cyclic alternating load, discussed the influence of different geometric parameters on the fatigue life of cast steel bifurcated joint, studied the fatigue performance of cast steel bifurcated joint under wind load and wave load, and found that the fatigue life at the intersection of main and branch pipes was the lowest, It is the weak link of three bifurcation cast steel joints.
In the research of mechanical properties of cast steel materials, relevant scholars have studied the fatigue mechanical properties of cast steel materials. Svoboda carried out fatigue test research on five kinds of cast steel materials with different chemical composition, heat treatment mode and mechanical properties; The test results show that the fatigue limit of cast steel at room temperature is 195 ~ 293mpa (stress ratio r = – 1); The exponent of paries formula of fatigue crack growth rate is 3.03 ~ 4.33, and the threshold value of SIF is 8.1 ~ 10.21mpa m2. Li Jing of Southeast University conducted material fatigue test and Analysis on gs20mn5v cast steel widely used in engineering, obtained relevant fatigue performance data, including complete S-N curve and fatigue limit, and analyzed the section of fatigue sample, which provided a reference basis for practical engineering application.
Zhang Pei of Beijing Jiaotong University conducted SEM tests on five materials: Q235B seamless pipe base metal, welded pipe base metal, heat affected zone, weld and g20mn5 cast steel. Based on the GTN damage model theory, the numerical simulation and parameter analysis of three unidirectional tensile notch specimens of various steels were carried out, and the GTN damage parameters of five steels were identified and compared.