| The fatigue life of welded structures is a major problem in the welding industry, there are many factors that affect the fatigue life of welded structures, such as structural factors, materials, internal organization, the welding process parameters, the working conditions, etc. so it is difficult to study. The cutter of Hard Rock Shield is a large welded structure. The fatigue failure takes a large proportion of the failure of the cutter. Estimating the fatigue life is very import to the use of the shield machine.Based on the actual structure of the cutter, and reasonable to simplify extracted from the welded structure of the T-shaped welded structures and Rectangle shaped as a research object. The research includes stress distribution, stress concentration, the S-N curve of the welded structures. The specific circumstances are as follows:(1)The stress and strain diagram of the cutter in normal working condition is got by simulation analysis, and determined the maximum point of the force on the cutter.(2)The stress distribution, stress concentration, the safe factor and fatigue sensitivity of the welded structure is got by simulation analysis, and the dangerous parts and crack prone parts of the distribution of the welded structure is determined.(3)The fatigue test is design and completed by author, and then obtained the S-N curve. Thickness changes of the T-shaped welded structures learned through trial no obvious impact on the fatigue life, The crack generate near the(4)By experimental data obtained, the local stress and strain and simulation combining the initiation stage of life estimation method is feasible for T-shaped welded structures.Eventually obtained the fatigue characteristics of these structures bye simulation analysis. The authors also propose a combination of local stress and strain in the stress-strain and simulation analysis. And use experimental data to validate this method can be used to estimate the initiation stage of life for the T-shaped welded structures. |
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