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A finite element simulation model is established for the gearbox body of 120B metro vehicle model in China. The fatigue strength, static strength and safe nose strength of the aluminum alloy and the nodular cast iron gearbox are calculated by the finite element method; the results show that the maximum equivalent stress of the aluminum alloy case is larger than that of the nodular cast iron case, and the maximum difference ratio is 36.3%. The static strength and type test of aluminum alloy and nodular cast iron box are compared. The results show that the maximum stress of aluminum alloy case is greater than that of ductile iron, and the difference ratio is 8.3%, the maximum sound power and vibration value of the aluminum alloy case are greater than that of the nodular cast iron case, but the average bearing temperature decreases by about 10 ℃. Although the strength of the aluminum alloy case is weaker than that of the nodular cast iron case, the overall factor of safety of the aluminum alloy case is higher than that of the nodular cast iron case, and can still meet the service life of 33 years or 9.6 million km requirements. In this paper, the applicability of aluminum alloy box is analyzed. The results show that both aluminum ductile iron and aluminum alloy can be used in metro gear box, and can be based on the specific requirements of the vehicle preference selection in the design.

Expressions such as “experiment” and “test” , “experimental site” and “testing site” , “China SeismicExperimental Site” and others “experimental site” , “scientific projects deployed in experimental site” and “experimental site’s scientific projects” might be confused at first glance, although they actually have different meanings. This paper aims to differentiate them and thus to deepen our scientific understanding of China Seismic Experimental Site.

According to the common structure characteristics of the plug-in fillet weld, a new weld defect detecting method was presented in this paper. The flexible phased array probe was inserted into the internal surface of the tube under water immersion during the detection process. The beam focusing model of convex flexible phased array was theoretically analyzed. Meanwhile, the acoustic focus beam with CIVA software were simulated. The typical flaws were added to the model of plug-in fillet weld, and defect response were obtained. The sample of the plug-in fillet weld with artificial flaws is manufactured, the system was calibrated in the laboratory. The experiment results indicated that this technique can successfully detect the typical flaws of crack, slag and porosity. Finally, the technique was applied to the manufacture quality inspection of the products, one incomplete penetration and one porosity were detected. The detecting system can effectively ensure the general welding flaws of the product were detected.

The adhesive joint of composite materials is one of the typical structures in aircraft structures, and the delamination damage is one of the most important damage modes in composite adhesive joints. In this paper, static and fatigue tests were carried out on L-shaped adhesive joints to analyze the damage evolution and failure modes of delamination damage under static and fatigue loadings. Based on the cohesive constitutive models, the static and high-cycle fatigue delamination constitutive models were developed. The static and fatigue numerical models of composite L-shaped adhesive joints were established by using finite element software. The stress distribution, deformation modes and delamination propagation laws were systematically studied. The simulation results are in good agreement with the experimental results. The delamination damage initiation, evolution and failure mechanism of L-shaped adhesive joints under static and fatigue loads were revealed by combining the experimental and the numerical results, which will provide theoretical and engineering guidance for strength and fatigue analysis of composite adhesive structures.

Explosive welding technology is a high-energy processing technology,which has been widely used in industrial practice. The residual stress produced by explosive welding process has an important influence on the strength and stability of the structure. So it is necessary to study the reasonable range of residual stress and seek to predict,control and adjust the residual stress. In this paper,the hole-drilling method is used to test the residual stress of 316 L/SA516 explosive welding plate. The basic principle of hole-drilling method for measuring the residual stress,the preparation of the test and the matters needing attention in the test process are introduced. The residual stresses measured by hole-drilling method mainlyanalysis explosive residual stresses,normalized residual stresses and residual stresses in the direction of explosive thickness. The development rule of the measurement results is basically consistent with the actual situation.