| As a kind of construction machinery for all-terrain operations,crawler excavators have complex types of road excitations and unpredictable operating conditions.Its components are subject to various complex and changeable loads for a long time,and fatigue failure is prone to occur,which affects the normal operation of excavators.In severe cases,it may cause major safety accidents,causing casualties or property losses.In order to improve the safety and reliability of excavator parts and solve the problems of excavator user operating conditions research and the lack of accelerated fatigue test methods,this paper proposes a method for constructing a crawler excavator accelerated fatigue test pavement based on user operating conditions.And analyzed the fatigue life of excavator parts under the excitation of the road surface.The main research contents and results are as follows:(1)Taking the excavator fuel tank as the research object,through user working condition investigation and data feedback,combined with the existing conditions of the quarry and the excavator development experience,nine quarry test conditions including flat road walking were constructed.Through the actual vehicle test in the quarry,the acceleration time history data of the fuel tank under the excitation of these 9 operating conditions are extracted,and based on the vibration fatigue theory,Calculate the target total Fatigue Damage Spectra and the maximum envelope of Shock Response Spectrum of the fuel tank during the full life cycle.(2)Using bump spacing on the road and excavator speed as variables,24 enhanced roadspeed conditions were constructed,and the excavator dynamics simulation analysis was performed under excitation of each operating condition,and the time domain data of fuel tank acceleration was extracted.Based on the Vibration Fatigue Theory,the Fatigue Damage Spectra and Shock Response Spectrum of the fuel tank under different enhanced road-speed conditions are calculated.(3)Using the enhanced pavement bump spacing and the excavator speed as variables,24 enhanced pavement-speed conditions were constructed,and the dynamics simulation analysis of the excavators under the excitation of different enhanced pavement and different gear speed conditions was carried out.The acceleration time domain data of the fuel tank is extracted,and based on the vibration fatigue theory,the fatigue damage spectrum and the shock response spectrum of the fuel tank under different enhanced road-speed conditions are calculated.(4)The optimal logarithmic fitting method is adopted,and the closeness of the Fatigue Damage Spectra of the enhanced road combination working condition to the total Fatigue Damage Spectra of the user’s actual working condition target is used as the fitting target,and the information of different enhanced road combination working conditions is obtained.The strengthening coefficients of each combined working condition are calculated by the strengthening coefficients.The results show that the three working conditions of 0.3m bump pitch 1st gear,2m bump pitch 1st gear and 15 m bump pitch 1st gear constitute the best strengthened road combination working condition.The strengthening coefficient is 15.1,which can guide the construction of accelerated fatigue strengthening test pavement.(5)Use ANSYS Workbench to perform finite element analysis on the fuel tank,obtain the stress distribution of the fuel tank under unit load,and combine the fatigue life analysis theory,the material SN curve and the load time history under the excitation of optimal enhanced pavement combination conditions,in n Code The life prediction of the fuel tank is carried out in the Design Life fatigue analysis software.The results show that the fatigue life of the fuel tank is 1102 h under the excitation of optimal enhanced road combination conditions.Compared with the effective life of the fuel tank under the excitation of actual operating conditions of14400 h,test time cost reduced to 1/13. |
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