Lightweight Design And Fatihue Life Evaluation Of Main Girder Structure Based On Gantry Crane

Crane is widely used in engineering construction,port transportation,petrochemical and traffic engineering and other fields,which is one of the important equipment of industrial production and infrastructure construction.To conform the development trend of structure rationalization and green,the research focus at home and abroad is to evaluate the fatigue life effectively,timely overhaul and maintenance in the safety period,and ensure the safe and reliable operation of the crane while aiming at the lightweight design of the crane,maximizing the utilization rate of its materials.In this paper,supported by "Research on Fatigue Life Prediction and Reliability Analysis Method for Main beam Structure of Railway gantry Crane of 20000kN"funded by Henan Province Postdoctoral Program,a large gantry crane is taken as the research object,and the light weight design of its main beam structure is carried out by using modern swarm intelligent bionic algorithm,and conducts research on fatigue life,which provides theoretical reference and basis for the safe operation of the crane,and also provides a reference method for other hoisting machinery lightweight design or fatigue life prediction.Firstly,a multi-strategy fusion algorithm(MIGWO)is proposed based on the Grey Wolf algorithm(GWO).Through the experimental simulation of multiple single and multi-modal standard test functions,the results show that compared with PSO,WOA,GWO,EGWO,BIGWO and MSGWO algorithms,the improved Grey Wolf algorithm based on multi-strategy fusion has obvious advantages in convergence speed,robustness and solving accuracy.In the meantime,the lightweight mathematical model of the crane main beam structure is constructed,taking the section parameter of the main beam as the design variable and the quality of the main beam as the objective function.The sensitivity of the design variables was analyzed based on the Sobol method and Spearman’s rank correlation coefficient method,and the main beam structure was optimized by combining the improved Grey Wolf algorithm with multistrategy integration.After optimization,the structural mass of the main beam was reduced by 11.79%.To achieve the purpose of reducing its quality and production cost.The finite element model of crane after optimization is constructed.The simulation analysis verifies whether the lightweight main beam structure meets the design requirements and determines the location of the fatigue prone points.The mathematical model of the lifting process of the crane is established,and the dynamic characteristics of the lifting process are studied.The finite element software ANSYS APDL is used to load the command flow to complete the simulation of the whole process of lifting and carrying of the crane.The first principal stress-time history of the concern is obtained,and the stress spectrum for fatigue life estimation is obtained by rain flow counting.Finally,the fatigue life of the crane main beam structure before and after lightweight is estimated,based on the nominal stress method and fracture mechanics method,combined with the stress spectrum.The results show that the lightweight design of the girder has a lighter weight.Although its fatigue life has decreased,its safety and durability still meet the design and use requirements.