The Mechanical Analysis And Optimization Design Of 20t Gantry Crane's Main Box Girder

This thesis elaborated the situation, dynamic state and the direction of the development of the logistics equipment domestic and abroad currently, and the important function of logistics equipment in modern manufacturing industry. The paper also studies the present condition of gantry home and abroad, and researches mechanical analysis and optimization design of the main box girder. According to the shortcomings that the main girder of the portal gantry with box girder is over-weighted, needs more material and the cost is too higher.The author goes into a deeply research on the 20t gantry crane that produced by DingXi crane factory. After studying masses of the data in the production application and comparing fully, builds a portal structure's parameterized FEM model using ANSYS internal command—APDL and parameterized method, which can modify and recalculate the model in FEM analyzing conveniently and quickly .This paper studies the structure of 20t gantry cranes static and dynamic mechanical properties. According to the static analysis, determines the danger points when the load at beam and the beam end position, and then checks the strength and stiffness of the girder; at the same time, Combing of the finite element parametric model, researches the modal analysis of the girder, gain the first 10 former natural frequency and mode shapes, and finally analyze the results. According to the modal analysis, the harmonic response analysis, ensures the deformation of the frequency bands dangerous situation, which provides the basis for the design.This article also studies the transient analysis of the 20t gantry crane when it lifting suddenly. Regard the contacting point which produced on the middle girder at the full load as basic point, analyses the vibration attenuation, gains the transient dynamic response which includes beam vertical displacement, vertical speed, vertical acceleration and time response curves, decay time. From the results, we can know that it meets the design specifications.The thesis researches mechanical analysis and optimization design of the main box girder based on the senior applied technique of ANSYS. From the results, we can see that the structure of the main box girder is more rational. After optimization. 12.4% material will be reduced, so if using the optimized result, can make to reduce the weight of the main girder, reducing the manufacturing costs.