Lightweight Design Of Bridge Crane Girder Constrained By D-S Theoretical Reliability

As a large material handling equipment,the bridge crane has a wide range of applications.As the country put forward the concept of green for the first time in "Opinions on Accelerating the Construction of Ecological Civilization",it is of great significance to design green bridge cranes to reduce environmental pollution.The main beam that serves as the main load-bearing role in the bridge crane metal structure occupies about 60% of the mass of the whole machine.Therefore,the prerequisite for green and lightweight research on the main beam structure is to ensure its safety.Therefore,it is very important to explore a lightweight design method for main beams that has high efficiency and can guarantee the safety performance of the structure.The main work of the paper is as follows:(1)The metal structure of the main beam of the bridge crane is analyzed,combined with the reliability calculation method of the D-S theory,the reliability calculation model of the main beam of the bridge crane based on the D-S theory is established.In view of the shortcomings of the original D-S theoretical reliability calculation method,an improved method is proposed.A numerical example verifies that the structure accuracy obtained by the improved method is much higher than the reliability result before the improvement under the premise of equivalent calculation.(2)The mechanical model of the main beam of the bridge crane is analyzed,and the optimization model of the main beam lightweight under the constraint of reliability is established.The division ratio between variables under the same focal element division number is analyzed,and the structural reliability calculation result corresponding to the selected variable division ratio of 16: 8: 4: 4 is used as the basis for reliability evaluation in optimization.In the optimization process,the method of repeatedly calculating the reliability value of the structural failure event is used to accelerate the elimination of unqualified data,thereby reducing the overall calculation.(3)Using C # language to compile "the bridge crane structure reliability calculation and lightweight analysis software based on evidence theory".The software can realize the rapid reliability analysis of the main beam structure and the optimal design of the size of the main beam section under reliability constraints.Verification through engineering examples shows that: using multiple calculation reliability methods reduces the overall calculation amount by about 50% in the optimization process,and improves the optimization efficiency.By comparing the results obtained after optimization with different reliability calculation methods,it is proved that the cross-sectional dimension optimization results under reliability constraints are safer than the deterministic optimization results and can achieve the goal of full optimization.