| The welding structure is the main form of structure in naval architecture and ocean engineering area. Because of the existence of inevitably initial defects (such as:cracks, slag inclusion, porosity) and welding residual stress, the welded joints has become the main parts which are prone to fatigue failure. Therefore, calculation of fatigue life to welding structure has become a hot object of current research in the field of architecture and ocean engineering. For solving the practical engineering problems, it is essential to master how to calculate the fatigue life of welding structure as well as analyze the influence on fatigue life of initial flaw size and welding residual stress.The thermal-mechanical coupled finite element analysis method is adopted in this paper to simulate butt welding process of material Q235, and then we get the results of horizontal welding residual stress distribution with the form of compressive to tensile to compressive stress along the weld direction.Based on the results of residual stress above, the stress intensity factor range of crack tip is solved by weight function method so that can calculate the crack propagation life of center crack on butt welding structure. By analyzing the influence of material constant, initial crack size, welding residual stress and the thickness of plate on fatigue crack propagation life, it shows that the material constant makes an obvious difference (1to2orders of magnitude) on the crack propagation life calculation using this method; By increasing the initial crack size and residual stress, the crack propagation life will be depressed; It has no significant impact on increasing fatigue crack propagation life by changing the thickness of this structure. |
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