The Residual Fatigue Life Study Of Concrete Pump Boom System Based On Multiple Load Case Analysis

In the process of long-term operation, parts’ residual life will decline gradually,then the accidents of cracking or even fracture are easily happened, which may causecasualty and property losses, so it is of great significance for guiding the safety use ofmachinery and parts manufacturing to predict parts’ residual fatigue life beforeremanufacturing. In this paper, taking concrete pump boom system as the researchobject, study load-time history at the end of boom system based on typical workingconditions of boom system in the actual operation of concrete pump, getting boomsystem fatigue life under multiple load case through experimental simulation andfinite element analysis, then establish boom system remaining fatigue life predictionmodel according to the residual life prediction related theory. This provides beneficialreference for further predicting parts’ residual fatigue life after remanufacturing. Themain research work of this paper is as followed.(1) Reviewing the research status of the residual fatigue life prediction methodsat home and abroad, discover the problems existing in the current study, then give themain research content and the general idea of this paper. Summarize the often usedfatigue life prediction methods at present, then select a fatigue life predicting methodaccording to the applicable object and advantages of each method, at last the boomsystem fatigue life prediction method of this paper is given.(2) Select several commonly used boom system postures as typical conditions,using DEWE data acquisition system to do concrete pump boom system stress test,and get the stress-time curves of each measured point. Build finite element model ofboom system in the finite element analysis software, then do static analysis,outputting finite element calculation result files, and do date analysis andtransformation by changing the load at the end of boom system and recording themeasured points’ stress, finally get the load-time history study at the end of boomsystem under multiple load case.(3) Inputting load-time history and the finite element models of boom systemrequired for fatigue life analysis in fatigue analysis software, set material properties,fatigue confidence degree and survival rate, selectting mean stress correction modeland fatigue damage theory, then get the boom system fatigue life under multiple load case. Boom system fatigue life experiment is carried out to validate the reliability ofboom system simulation fatigue life.(4) The boom system total fatigue life is calculated on the basis of the boomsystem simulation fatigue life under the selected condition by the expert evaluationmethod. Select parts residual life prediction model, then determine the boom systemhaving serviced life, insertting the boom system total fatigue life and having servicedlife in the selected residual fatigue life prediction model, and build the boom systemresidual fatigue life prediction model.