Research of numerical simulation of high strength steel welding residual stress and fatigue life By Chen Song
I
ABSTRACT They are very necessary and important to carry on the research on the welding residual stress prediction method of deep-sea pressure structure, analyze and understand its generating principles and distributing rules. Based on understanding the prediction method, generating principles and distributing rules, many suitable treatments and techniques would be used to remove/adjust welding residual stress and deformation during the designing and producing process. These works are very valuable engineering practice to improve pressure structure fatigue life. During the past researchthe effect of welding residual stress on fatigue life was only studied qualitatively. Based on numerical simulating technique, the butt-welding of high strength steel is simulated by a 3-D numerical method, and a satisfied engineering result is gotten. Weld and near heat-affected zone mainly having residual tension stress is discover. Longitudinal residual stress of weld is higher than transverse, and the residual stress of weld front zone is higher than the final.according to the erection techniques of high strength steel plates, the welding experimental plates and the erection techniques are designed. Contrast experiment of keeping and removing welding residual stress is done, and the experimental results are analyzed. Hyper-sound wave can remove about 400Mpa stress and bring bigger compression stress. Influence zones of welding residual stress on fatigue life are gained from the fatigue life experiment. Different residual stresses are in the two zones of weld, and they have very important effect on the fatigue life of welded joint.method of hyper-sound wave removing/adjusting residual stress can improve the fatigue life of welded joint,about 20%~40%. Keywords: pressure structure, welding residual stress, numerical prediction method, contrast experiment, fatigue life II
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