| The hydraulic cylinder of construction machinery often has poor working conditions,high working strength,vibration and impact conditions.It bears complex fatigue alternating stress and is prone to fatigue failure.The reliability analysis and fatigue life prediction of hydraulic cylinder have been paid more and more attention by enterprises.Taking the pressurized cylinder of rotary drilling rig as the research object,the finite element analysis of stress response characteristics,load spectrum compilation and fatigue life analysis of hydraulic cylinder are carried out in this paper.The specific work is as follows :Firstly,according to the parameters and working characteristics of the test prototype,a set of load spectrum test scheme for the pressure cylinder of rotary drilling rig is designed and developed.Based on the field drilling process of rotary drilling rig,the pressure load data of pressurized cylinder with and without rod cavity were collected.The cylinder stress load test was carried out synchronously to obtain the stress load data at the measuring point.MATLAB software is used to realize the pre-processing of pressure load signal,such as noise reduction and abnormal value elimination.Secondly,based on the pressure test results and the relevant parameters of the pressurized cylinder,the fluid-solid coupling analysis of the pressurized cylinder is carried out,and the finite element simulation results of different stroke positions under typical working conditions are obtained.The flow-solid coupling results were compared with the statistical results of pressure load to verify the correctness of the flow-solid coupling modeling.The simulation results of non-fluid-solid coupling conditions are introduced as a reference to prove the necessity of carrying out fluid-solid coupling analysis on the pressurized cylinder.According to the fluid-solid coupling simulation results,the dynamic response analysis of the pressurized cylinder was carried out,and the potential risk points of fatigue failure were marked according to the change of stress amplitude.Then,with the help of n Code software,the pressure load data after pretreatment are counted and counted.On the basis of the rain flow matrix obtained by counting treatment,nonparametric extrapolation and frequency extrapolation are carried out.The load classification and reconstruction were carried out based on the extrapolation results,and the full-life load spectrum of the pressurized cylinder that can be used for fatigue life simulation and bench acceleration test was prepared.Finally,the average stress of the material was corrected based on the fluid-solid coupling simulation results.Based on the linear cumulative fatigue damage theory,the fatigue life prediction of the pressurized cylinder was completed by using the n Code Designlife software.According to the fatigue life calculation results,the weak parts of pressure cylinder are determined.In view of the load spectrum compilation process and method,load extrapolation and fatigue analysis method in the research results of the fatigue life of pressurized cylinder in this paper,they can be applied to the same type of products.The results of fluid-solid coupling finite element simulation and fatigue life prediction can be used as an important reference for the structural optimization and reliability design of this type of pressurized cylinder. |
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