Tower Crane Jib Fatigue Crack Propagation And Longevity Research

With the continuous development of urbanization construction, the constructiondemand for tower crane (hereinafter referred to as the tower crane) is more and morebig, the tower crane load factors, job busy also is aggravating, occurrence collapse,armless and other safety accidents are increasing, the fracture of hoist boom of towercrane is most serious.The structure of tower crane is mainly lattice type space truss and mostly forwelding structure, therefore, the main form of failure is fatigue fracture. Tower cranewelded components due to welding defects or fatigue stress the interaction of the crackinitiation, crack existence will greatly reduce the fatigue life of components, but thecrack initiation and formation time is short, so its fatigue life mainly depends on thefatigue crack extension stage.In this paper, based on the theory of structural fatigue and fracture mechanicsknowledge, expounds the fatigue failure mechanism of tower crane structure anddamage types, according to the QTZ40tower crane’s structure parameters, based on theAPDL language and the Visual Basic software for tower crane boom encapsulateparameterized modeling, so as to realize the parameterized of tower crane structuremodeling and visualization；In the ANSYS finite element analysis software for towercrane jib static stress analysis, obtained34kinds of load conditions of stress positionsoutside the car to remove the roots of the two can not reach across the luffing jib towercrane, also shows the5typical conditions of stress distribution for tower crane jibfatigue strength of welded structures provide a basis for analysis; Considering theinfluence of residual stress at the same time, in ABAQUS finite element software, thecalculation of tower crane jib welded structure fatigue crack stress intensity factor, andthrough the simulation analysis of stress intensity factor of crack and a function ofcrack length, further analysis of its impact on the fatigue life of the tower crane boom; Finally, combining with the reference of QTZ40tower crane hoisting load data,preparation of tower crane load time history, and using the Fatigue analysis software tocarry on the tower crane structure Fatigue strength calculation and Fatigue lifeestimation, thus for safe use of tower crane, tower crane related detection rules andstructure of the reference for the security maintenance.