The weld life prediction of frame's damper seat based on notch stress model

Abstract

In order to analyze welded fatigue life of welded frame's accessories correctly, this paper adopts fictitious notch method of 1mm radius and establishes a notch stress model for an A1A-A1A-type locomotive bogie's primary vertical damper seat. Through FEM analysis, stress state at local weld toe and weld root for damper seat can be obtained. According to stress range, the danger points of welds can be confirmed. The full vehicle multi-body dynamic model is established for simulation analysis, for the sake of acquiring load-time history of vertical damper seat under track irregularity, which considering nonlinear damping speed character of vertical damper. Based on StressLife_Analysis module of nCode DesignLife, welded accumulative damage and life cycles under different stress parameters and fatigue class curves are calculated. Meanwhile, the corresponding nominal stress model is established to carry out analysis comparison. The result shows that in the same case, accumulative damage value calculated by a notch stress method is lower, life cycles is higher, and the normal stress method generally is partial to be conservative.