Bridge Crane Metal Structure The Lightweight Design Studies

In this dissertation, taking a 50t-31.5m double girder crane as the research object, based on the modern design methods of finite element and the structure optimization design, lightweight design of girder cranes has been carried out under various conditions, whose materials are Q235 and Q345 respectively.Firstly, researches of the crane and CAE technology in crane industry are investigated, and the theoretical basis of the finite element method has been researched deeply as well as Hyper Works. In chapter 3, the structure of this bridge crane is described in detail and the geometry model is established. In addition, finite element model of the crane bridge is established by using pretreatment software HyperMesh. In chapter 4, modal analysis and the static analysis of the whole and the half finite element model of bridge crane are carried out, and the calculated results show that the safety factor of the crane bridge structure is much too bigger and there exists some space for further optimization. So the lightweight design of bridge crane is necessary. In chapter 5, in order to verify the accuracy of the finite element model and the calculation results, static calculation of the bridge crane girder is made by using the analytic method, and the results are consistent with the finite element results, which ensure the credibility of the finite element method.In chapter 6, various structure optimization methods and their processes are researched deeply as well as structure optimization in Optistruct. Then the structure shape optimization, size optimization, topology optimization and comprehensive optimization of Q235 and Q345 girder cranes are orderly carried out under various work conditions. Moreover, the optimization design of the thickness of the variable cross-section girder and the optimization cross-section design of beam are researched. Establishing the mathematical optimization models of the bridge for different optimization designs is to the priority. Although each optimization model is different, the ultimate objective is the same to reduce weight of crane bridge and realize lightweight design. The researches show that the lightweight design structure of the bridge crane can be realized by the structural optimization under the premise of meeting the design requirements of strength stiffness, and that the effect is remarkable. Comparing the optimization results of Q235 and Q345 bridge, it can be observed that only increasing the strength of material cannot make great improvement of the comprehensive performance of the bridge crane, and the strength and stiffness must be intensified together, which results in better structure design. The design of the girder structure crane can be improved through the research in this paper, which makes crane box beam structure design more reasonable, and can provide a meaning design reference for the crane girder.