Research On Crack Propagation And Fatigue Life Prediction Method For Port Machine Structures Based On Sensitivity Model

As one of the special equipment,the port crane is an indispensable key element in port,river and other transportation occasions,and plays a pivotal role in the journey to realize the great rejuvenation of the nation in the new era.With the deepening of the development direction of large-scale crane,the operation safety of crane has been paid more and more attention.In recent years,many scholars at home and abroad have studied the influence of different parameters on the fatigue life of the crack structure of the port machinery,but most of the studies have not been able to conduct a quantitative evaluation of the influence of parameters fundamentally.Therefore,scientifically and accurately analyzing the impact of different parameters on the crack propagation and fatigue life of port crane structures is a key challenge that needs to be urgently solved in the current maintenance phase,which has great theoretical research significance and practical application value.In view of this,this paper proposes a sensitivity analysis model suitable for different variable ranges and quantities.Secondly,through the dynamic and static analysis of the port crane structure,and using the modified sensitivity model,the working condition parameters that have the greatest impact on its structural strength are analyzed,and then the dangerous section position and dangerous operation parameter range of the departure aircraft are determined.On this basis,the sensitivity model is used to analyze the influence of structural crack parameters on the fatigue life of port machinery according to the solution results of stress intensity factors of port machinery structure.Then,according to the determined dangerous crack parameters,the crack growth and fatigue life of the port crane structure are analyzed.Finally,based on the developed quantitative evaluation system of port machinery,the monitoring and acquisition scheme of stress,strain and vibration acceleration signals of the main beam of port machinery is established from a multi-dimensional perspective,and the test results are compared and analyzed.The specific research contents are as follows:(1)The establishment of sensitivity correction model based on intelligent optimization algorithm.By combining Kriging optimization algorithm with polynomial response surface,a sensitivity model based on PRS-Kriging correction is proposed.On this basis,aiming at the problem of uncertain variables,the PCE coefficient of polynomial chaotic expansion is solved by the Variable Bayesian intelligent optimization algorithm,and the model is optimized by the proper orthogonal decomposition reduction algorithm.A sensitivity model based on VB-PCE and the reduction algorithm is proposed,and the feasibility and accuracy of the proposed sensitivity analysis model is verified by an example analysis.(2)Structural strength analysis of port machinery based on modified sensitivity model.After determining the structural influence parameters,carry out the experimental design of the coupling parameters,and then extract the load of the crane trolley on the main beam structure of the port crane in different test groups through the structural multi-body dynamics analysis,and then conduct the structural static analysis of the extracted load value.On this basis,the sensitivity values of different test groups are solved by the proposed PRS-Kriging modified sensitivity model,and the quantitative sensitivity analysis of the influence of different state parameters on the structural strength of port machinery is realized,with the average prediction accuracy of 95.31%.The results show that the sensitivity value of the trolley position is 0.5318,which has the greatest impact on the structural strength of the port crane;The sensitivity value of the trolley lifting speed is only 0.0494,which has a small impact on the structural strength of the port crane.(3)Analysis of crack propagation and fatigue life of port machinery based on sensitivity model.Firstly,the crack location and characteristic parameters of the port machinery structure are determined to achieve quantitative analysis of the impact of multiple uncertain variables on the structural stress intensity factor.The average prediction accuracy can reach 93.34%.On this basis,the crack propagation degree of the port crane structure at different positions is analyzed,and the fatigue life of the entire structure of the port crane and the structure with cracks is solved using finite element software.Based on this,the impact of crack propagation on the structural life of the port crane structure is determined.The research results indicate that the crack at the front tie rod position of the main beam has a significant impact on the structural stress intensity factor,with the maximum influencing parameter being the crack angle,with a sensitivity value of 0.543;The minimum influencing parameter is the crack cross-section radius,with a sensitivity value of 0.084.The crack angle has the greatest impact on the structural crack propagation rate,and the crack cross-section radius has the smallest impact on the structural crack propagation rate.(4)Development of quantitative evaluation system for port machinery.From the perspective of multiple evaluation indicators,the acquisition steps of stress,strain and vibration acceleration signals of the main beam structure of the port machine are established.By adjusting the operating parameters of the port crane and combining the stress and strain of the main beam structure to verify the structural strength,the average solution accuracy can reach 93.53%.The analysis results of structural fatigue crack propagation are verified by presetting the structural crack parameters of the port machinery and combining the vibration acceleration signal of the main beam structure.On this basis,design hardware equipment for debugging experiments,conduct experimental testing and comparative analysis,and verify the accuracy and feasibility of the research method proposed in this article.