Issue 48

B. Chen et alii, Frattura ed Integrità Strutturale, 48 (2019) 385-399; DOI: 10.3221/IGF-ESIS.48.37 390 dynamic loads are multiplied by 1.4 and cycle  6 0.2 10 times. The equipment and specimen for fatigue test are shown in Fig. 5. Fig. 6 describes the strain gauge type at the welding of bogie frame. Base metal Butt welds Other welds x y x y x y 170 170 155 155 155 155 84 170 88 155 101 155 -50 78 -58 60 -66 45 -170 -170 -170 -170 -170 -170 -50 -170 -58 -170 -66 -170 84 -2 88 21 101 47 170 170 155 155 155 155 Table 5 : Turning point value of GSFLD of steel with tensile strength greater than 420MPa Figure 7 : Schematic diagram of bogie frame patch layout Figure 8 : Fatigue analysis results of bogie frame Fig. 7 presents part of the strain gauge position of the bogie frame. It can be seen that the location of the patch is mostly the weld, which indicates that the evaluation of fatigue strength of the weld is more important. Then, compared with the position of the weld shown in Fig. 3, there are fewer test points in the experiment, which can't reflect the fatigue situation of all welds. Hence, the combination of finite element simulation and experiment can more accurately evaluate the fatigue strength of the bogie frame. Figure 8 displays the fatigue strength analysis results of the frame based on GSFLD of ORE B12/RP17. The GSFLD given in Fig. 8 are basically similar to those in Fig. 4, which include GSFLD of base metal, butt weld and other weld. The difference is that the limit values of the turning points of GSFLD in Fig. 4 are based on steel with tensile strength greater than 520 MPa, while those in Fig. 8 are based on steel with tensile strength greater than 420 MPa. However, because the maximum yield strength of bogie frame is 355 MPa, which is less than the steel used in GSFLD, Therefore, both types of GSFLD can be used as standard to judge whether the fatigue strength of the frame meets the requirements. In order to increase the evaluation range of fatigue strength, the GSFLD of steel with tensile strength greater than 520 MP is generally selected in the actual simulation analysis Tab. 5 shows the limit value of the turning point corresponding to the GSFLD in Fig. 8. It can be seen that the fatigue strength analysis results of each test point are basically in the GSFLD of the weld, which meets the standard requirements. However, some of the test points are beyond or near the GSFLD, which is more dangerous to the fatigue design of the frame. As can be seen from the comparison between Fig. 4 and Fig. 5, the results of experiment and simulation are basically the same. Since the simulation calculation has continuity in extracting the fatigue strength analysis results of welds, there are more over-standard points. It can be seen that it is feasible to analyze the fatigue strength of bogie frame with simulation analysis in the design stage, and the calculation results are more accurate and reasonable. It can provide some guidance for the anti-fatigue design of bogie frame in detail design stage.