Research On Hot Spot Stress Evaluation Approach Of Welded Bogie Frame On High-speed Trainset

In this paper, the hot spot stress evaluation method is studied for evaluating the fatigue strength of welded structure. By finite element analysis and hot spot stress fatigue strength evaluation for typical weld joint, the special hot spot stress fatigue strength evaluation is established for high-speed trainset welded bogie frame.In theoretical item, the applicable range of hot spot stress approach is firstly studied by discussing the effect of weld leg and plate thickness to stress distribution of weld joint for load-carrying cross fillet joint. And the finite element calculation method of hot spot stress is researched by taking the ring fillet joint for example, and discussing the effect of element type, element size and extrapolation method to precision of hot spot stress to get a proper meshing method and extrapolation formula, to make a basis on following hot spot stress calculation of local welded sample.In practical application item, UIC515 Code is firstly applied for analyzing the complete welded frame by finite element method to get the area with bigger nominal stress and lower fatigue behavior, and then study the hot spot stress fatigue strength evaluation approach of the typical fillet ring joint at the connection of tubular transom and side frame, the plate to plate end weld between side frame web plate and anti-yaw damper hold and the non-close ring end weld at the connection of braking unit hold and tubular transom. Before the evaluation, above-mentioned 3 study objects should be firstly simplified to get the relevant geometrical stress concentration factor and hot spot stress fatigue limit as the basis of the hot spot stress fatigue evaluation. During the analysis, the submodelling technology is applied to refine the element, and the stress equivalent method is also applied for evaluating the fatigue strength of joint under multi-stress state. At last, by comparing the nominal stress approach and hot spot stress approach, it is resulted that comparing with nominal stress approach, the hot spot stress approach is more scientific and serious with respect to evaluate the local detailed structures.