The Dynamic Characteristic Analysis On The Structure Of Gantry Crane

Gantry crane is absolutely necessarily equipment in our national development of economy. Gantry crane will bring impact and vibration to the system, because both the weight of steel structure is the weight of entire machine above 60% and the steel structure support mechanical load at work. It will cause metal structure to fatigue destruction if steel structure is influenced in the vibration for a long time. At the same time, the vibration of system is disadvantageous to the operator if the parameters aren't reasonable. Therefore, it has become the study emphasis, which investigates dynamic characteristic on the structure of gantry crane in the design domain.Relied on practical engineering project, the paper studies a gantry crane. It investigates more thoroughly on the urgent solved problem of dynamic characteristics in the design and analysis of gantry crane by using computer aided finite element analysis software named ANSYS and estimates the fatigue life with the results. The paper provides concrete analysis methods. The main work is as follows:Firstly, the paper has investigated finite element theory mechanical vibration theory analytical method of computer aided engineering and fatigue design theory. It analyzes and investigates gantry crane structure through summarizing the practical project experience. The paper establishes the scientific and optimizied finite element computing model. It insures that the computation gets analysis results more accurate.Secondly, through the modal analysis on the structure of gantry crane with the Block Lanczos method, the first fifteen natural frequency and vibration modes are calculated when the trolley with full load is in the middle of the span. In addition, the varying laws among the natural frequency w_i of gantry crane and the mass, the stiffness of gantry structure, thestiffness of steel wire, constraint, are analyzed.Thirdly, through the transient response analysis with the FULL method, the displacement, velocity and acceleration time course responses in the middle of the span are calculated when the structure comes under the lifting impact load and the trolley with full load is in the middle of the span. In addition, the varying laws between the dynamic coefficient of the lifting and the lifting velocity are discussed.Fourthly, the fatigue life of girder structure with the damage tolerances design method is calculated. The paper establishes the model of crack's spread based on Paris formula andcalculates the design life of girder when the initial crack size of the under-board reaches 0.5mm near the middle of the span. In addition, the varying laws among the life of girder and the parameters of model are discussed.Modeling and analyzing large complex structures as gantry crane with international known integrated CAE software may economize manpower and material resources. At the same time, it has higher simulation precision and solves the real problem in the engineering. The results offer useful references for the optimization design -. the choice of dynamic coefficient of the lifting, maintenance and remedy of gantry crane in the future. The interrelated calculation methods have also some reference values to the design and analysis of the structure such as gantry crane.