Miter Gate Structure Fatigue Analysis Under Wave Loading

Miter gate has become a main door type of large and medium-sized ship lock, because of its reasonable arrangement form, convenient and reliable operation, smaller hoisting capacity and saving in material. In the process of actual operation, fatigue cracking problems existed in ship lock miter gate. Finite element analysis and water elastic material model test of miter gate of large ship locks has been developed by Scholars at home and abroad, mainly based on the structural internal force calculation of miter gate, fatigue cracking study very little. Therefore, in using the appropriate analysis method of ship lock miter gate, on the basis of structure internal force calculation, to further expand the study of structural fatigue, and put forward reasonable fatigue resistance measures, has important theoretical and practical significance.In this paper, ANSYS finite element software is used to establish a three dimensional space finite element model of miter gate structure. Relying on engineering select different working conditions to carry out finite element analysis and calculation, and based on the theory of structural fatigue, FE-SAFE fatigue calculation software introduced analysis of the fatigue life of miter gate. Main conclusions are as follows:1、Under design condition, the overall structure of the miter gate is projected toward the downstream side, structure deformation and stress showed a trend of symmetrical distribution, the maximum equivalent stress and maximum deformation are located in the middle and lower side panel. The panel structure plays the important role of water retaining and load transferring, in local place such as the joint of panel and girders, there is stress concentration phenomenon. Girder structure as the main stress components, the maximum stress appears at the end of main girder, the maximum deformation appeared in the mid-span of main girder structure, web place stress value greater than the upper and lower flange, prone to buckling deformation.2、Under high water conditions, the water level of lock chamber inside and outside is high, and hydrostatic loads in a wide range of miter gate, the maximum stress and deformation are located in the upper panel. Because of the miter gate of main beams arranged according to the load, the bigger spacing of upper girder lead to 3、the stress and deformation of upper structure will increase. Two kinds of conditions, the difference of maximum deformation is54.41%～68.69%, the overall equivalent stress is55.65%～64.08%, the change trend of both stress and deformation differs very big.4、Miter gate under wave load of the fatigue analysis results show that fatigue damage mainly appears in the panel and the main beam joint with the main beam end. Wave height values increase from0.1to1.5m, miter gate logarithmic fatigue life value is42.3%. The linear increment of wave height value, the miter gate of fatigue cycles in accordance with the exponential decline.4、Other factors analysis showed that residual tensile stress results in the decrease of miter gate fatigue strength, residual compressive stress results in turn; material surface parameters and the gate is inversely proportional to the fatigue life, surface parameters is less than1.5, the structure fatigue life decreasing speed, decreasing trend slows down when more than1.5.5、In miter gate design, from the structure of local design, select material, residual stress control, to reduce the stress amplitude and reduce the material’s surface parameters such as five aspects to improve structure fatigue strength.