Research On Lightweight Design Of Main Girder Of Bridge Crane Based On Improved Gravitation Search Algorithm

In recent years,China has been vigorously developing high-end manufacturing industries.As a widely used material lifting equipment in the manufacturing industry,bridge cranes must be developed in a lightweight and intelligent manner.The traditional bridge cranes currently used in China are over 30% heavier than European cranes.Therefore,how to adjust the size of the structure so that the safety performance and light weight of bridge cranes are optimally distributed has become a work that most researchers need to complete.As the main bearing structure of the bridge crane,the main beam accounts for about 60% of the total weight of the crane.Therefore,it is of great significance to optimize the main beam structure.This paper takes the box girder of 32 t double-girder bridge crane as the research object,based on the improved gravity search algorithm(IGSA algorithm),optimizes the design of box girder cross-section dimensions,so that the main girder meets the crane design safety criteria,To achieve the goal of lightweighting,and then realize the weight reduction requirements of the entire machine.The main research work of the thesis has the following aspects:(1)Based on the principle of gravitational search algorithm(GSA),aiming at the shortcoming of premature convergence of GSA algorithm,the IGSA algorithm is proposed by introducing t distribution variation,improving the mutation strategy and adding the inertial weight of inertia weight.Through the simulation of the test function Rastrigrin,the results show that the IGSA algorithm significantly improves the shortcomings of poor local development ability and low search efficiency of the basic GSA algorithm.(2)The structure of the girder and the stress conditions were studied.The main girder structure was simplified,the main metal frame was retained,and the optimized front girder model was established.The stress,vertical displacement and modal analysis were performed using ANSYS.The analysis results provided reference for subsequent optimization work.(3)Select the appropriate parameters of the IGSA algorithm with the cross-sectional area of the box girder model as the objective function.Using GA,GSA,and IGSA to optimize the objective function,iterate the objective function,select the appropriate iteration result to round the value,and compare the data shows that the optimization result of the IGSA algorithm is better,so that the cross-sectional area of the main beam is reduced by 15.04%.(4)In order to perfect the optimized main beam model,the arrangement of stiffeners is determined by calculation.The finite element analysis of the stress,vertical displacement and modal frequency of the optimized main beam structure under hazardous conditions was performed one by one.Compared with the original structural analysis results,the feasibility of the optimized scheme was verified and the purpose of lightweight design was achieved.