Research On Fatigue Life Of Welding Seam Of Bridge Crane Based On Verity And Sub Model

Main grider is the main metal structure of bridge crane and it plays the most important role in load bearing. Under the action of random load it is prone to fatigue fracture which can cause terrible production accident. Due to the effects of welding process, main beam weld tends to produce welding defects and stress concentration in actual production. Welding defects and stress concentration form crack source under the action of random load, affect the fatigue life. As the weakest part of the fatigue life of the main beam, the fatigue life analysis of weld line is the core of the whole machine safety problem. In the past, most of the fatigue analysis of the main girder only pay attention to its structure, but not the influence of the welding seam on the fatigue life of the main beam. In view of the above reasons, this paper has carried on the following analysis research.Firstly, I created a 3D model and imported it into the analytical software ANSYS. Then I carried on analysis on bridge crane main grider under four different working conditions, through which I got the result of stress and deformation distribution, determined the structure stress and deformation of the highest value of the location, to verify the strength and stiffness of the requirements in line with the requirements.Secondly, we established the finite element model with the welding seam details of the middle of bridge crane by the method of "shell to solid" sub model and obtained the equivalent stress distribution of sub model. The sub model was imported into the FE-SAFE fatigue analysis software, and the Verity method was used to analyze the fatigue life of the welded joint of four different locations in the main beam, and the welded seam which has the minimum fatigue life was found.Finally, optimization analysis was done by changing weld toe length of this weld(equal and unequal). Calculation analysis shows that when using scalene weld and long side lies in bottom flange side weld toe the anti-fatigue performance is best; optimization analysis was conducted by changing the surface form of same weld(concave, convex, plane). Calculation analysis shows the weld with concave cross-section form has the longest fatigue life, and the plane weld has the best economic performance. The bridge crane with a higher working level(7?A) is adviced to use scalene concave weld cross-section form. This plays a certain guiding role in the selection of the weld section shape of the bridge crane box girder.