Bridge Crane Box Girder Structure Fatigue Life

At present, Bridge crane has been widely used in railway traffic, steel chemical in port and logistics departments and locations, as a modern industrial production and transport of essential special equipment. However, bridge crane hide the most dangerous factors and the casualty accidents rate of mechanical equipment in the special equipments, every year there are lots of continuous frequent lifting equipment accident at home and abroad, which causes the extremely serious personal injuries and property damages. According to a survey data shows, the commonest malfunctions, which are also the most important malfunction,are malfunctions characterized by cracks in metal structure of cranes. Bridge crane girder bearing structure is the main component, bridge cranes features determine the main damage in the form of such structures as the main beam under random loading fatigue fracture, which means that the main beam of the broken bridge End of life crane. Therefore,the researches of reasons about how cracks occurred and the trends they will expand to,for preventing the happening of the fatigue fracture and guiding the product design,manufacturing,testing and management,are of great importance.In this paper, using modern fatigue damage theoretical knowledge research crane box girder bridge fatigue damage characteristics and using large-scale finite element software ANSYS to analyze the statics analysis on the bridge structure for Figuring out the main reasons on malfunctions,to assess the structural performance and fatigue life.In addition, the project also has been combined with fracture mechanics theory of cracks in the structure of box girder residual fatigue life prediction, which works for improving the reliability of crane and extending its life, thus improving the activities in the production of crane productivity with a guiding significance.First of all, in this paper , operating the finite element model on box girder structure of the bridge cranes, choosing the structure of the five kinds of typical working conditions crane in real work, in approximate fatigue load distribution condition of state of the box girder without defect of the finite element analysis, structure of the box girder structure is obtained in each working conditions of stress, displacement deformation and safety factor distribution, determining the box girders structural stress value and displacement the biggest position and deformation of the lowest parts safety coefficient.Then, using the ANSYS finite element analysis software containing the module of life analysis of the initial crack girder bridge crane structure design of life, and through the simulation result estimation and analysis of the initial crack containing box girder structure in approximate the safety factor of the actual conditions and fatigue life of convective map, intuitively reflects box girder structure of each place fatigue life distribution state.Finally, on this subject,adopting linear-elastic fracture mechanics method to estimate the welding structural accumulated fatigue crack extension life on the bridge—like crane under the random load and to calculate and draw out graphs about the extension of cracks on the web plates of end beams on cranes and cycle curve of this machine. We found that the results of the finite element simulation analysis on bridge statistic performance is more reliable, that is also show the estimation method on fatigue life of the box girders structure is feasible.