| Hoisting machinery is one of the indispensable special equipments in modern manufacturing.It mainly plays a role in the handling of large materials.It is widely used in practical engineering because it improves production efficiency and greatly reduces people’s labor intensity.When the crane is working,the main beam is subjected to the alternating load brought by the lifting cargo.As the service life increases,the micro-damage such as slag inclusions and pores caused by welding and smelting in the metal structure will accumulate continuously.When the critical value is reached,fatigue damage will suddenly occur,which is extremely harmful to society,so it is necessary to evaluate its reliability.At present,the fatigue reliability analysis method for crane metal structures mainly uses fatigue amplitude as a random variable for fatigue reliability analysis.However,the actual situation is that the material properties,crack size and crack shape of the box beam are also very large.Certainty,therefore,in order to improve the accuracy of the reliability analysis of the fatigue life of the box-shaped main beam structure,the uncertainty of these parameters should also be taken into consideration.This paper takes 36 TU container gantry crane as the research object,discusses the acquisition and preparation of fatigue load spectrum,fatigue expansion process,fatigue life estimation,fatigue reliability analysis method and reliability calculation.The main contents are as follows:(1)The preparation of the fatigue load spectrum of the crane structure is studied.The determination of the fatigue hazard location of the crane structure,the dynamic sampling of the stress-time history and the idea of ??data processing are analyzed.(2)The fatigue life estimation method of crane is discussed.The expression of stress intensity factor is calculated.The fatigue crack propagation process and da/d N formula are studied based on fracture mechanics.The estimation model of fatigue life of crane structure is established by Paris formula..(3)Exploring the applicability of traditional probabilistic and non-probabilistic reliability analysis methods in the field of cranes,this paper proposes a reliability-non-probability hybrid reliabilityanalysis method to analyze the fatigue life of crane box girder.(4)Based on the theory of fracture mechanics,several different calculation models for crane fatigue reliability are studied.The distribution of fatigue expansion parameters is analyzed,and the parameters lacking the distribution information are quantified by interval variables.The probability box-non-probabilistic reliability analysis theory is combined with the crane fatigue residual life safety margin equation to establish the crane box girder.Fatigue mixing uncertainty reliability calculation model.(5)Using Matlab software to discriminate and fit the fatigue stress spectrum,the hybrid reliability analysis method is used to calculate the fatigue hybrid uncertainty reliability calculation model.Then the parameter hypothesis of lacking distribution information is reduced to a random variable,and the traditional probability reliability Monte Carlo method is used to solve the two methods.The results show that the probability-non-probability hybrid reliability analysis method is used for the crane structure.It is safer to perform fatigue reliability analysis. |
PDF Full Text Request