Research on high-cycle fatigue life of pontoon bridge connection joints using improved stress field intensity method

Le résumé fourni par la source

Based on the fatigue life data of 30CrMnSiA steel and fatigue tests of pontoon bridge connecting joints, this study improves the stress field intensity approach. In the absence of fatigue life data for smooth specimens, a method for determining the spherical center of the fatigue damage zone in standard notched specimens was established by combining fatigue tests. Consequently, a general method for calculating the stress field intensity radius, applicable to 30CrMnSiA standard notched specimens with arbitrary stress concentration factors, was derived and applied to the pontoon bridge connecting joint, providing a generalizable framework for calculating the field intensity radius of notched components. Subsequently, the stress field intensity of the joint was calculated using ANSYS Workbench software. Factors influencing structural fatigue life, such as size and surface condition, were incorporated, and the model was calibrated based on experimental results to predict the fatigue life of the pontoon bridge connecting joints.The results show that the improved stress field intensity method, which does not require fatigue life data of smooth specimens, significantly extends the applicability of the original stress field intensity approach. The minimum clearance between the single lug and the double lugs in the pontoon bridge connecting joints has a pronounced influence on the location of fatigue failure and the fatigue life of the joints. Under stress-controlled fatigue conditions, the location of the spherical center of the fatigue damage zone in the notched joint can be predicted using the maximum stress amplitude, and the predictions are in good agreement with experimental results. The predicted high-cycle fatigue life of the pontoon bridge connecting joints in the range of 104–105 cycles obtained using this method shows high accuracy, with errors within 10%. The good agreement between predictions and experimental results demonstrates the high practical value of this method. This research provides a practical and feasible scheme for the fatigue life assessment of single-lug and yoke joints.

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