Fatigue residual life prediction of casting crane under track defect model

Abstract

For the safety problems caused by abnormal changes of stress-time history at fatigue risk points of casting crane metal structure due to the vertical impact effect of track defects, the forecast method of fatigue residual life of casting crane under track defect model is proposed. Guided by the kinematics and dynamics theory, the kinematic-dynamic model of dynamic load resulted from crane travelling on defective track including the highlow dislocation and horizontal gap is established. The influence of track defects on the vertical impact effect of operation crane is analyzed. Furthermore, combining with the collection of technological process and usage of casting crane, the characteristic parameters needed in the process of stress spectrum acquisition are determined. The allowable stress method combined with finite element simulation is used to get the fatigue risk cross-sections and points of crane metal structure and the first principal stress-time histories of dangerous points are obtained. The double parameter stress spectrum of dangerous points is extracted by rain flow technology. Based on fracture mechanics and damage tolerance design, the fatigue residual life of dangerous points is estimated by Paris formula. Taking the 100/40t-28.5m casting crane as an example, the feasibility of the above model and method is verified.

Fatigue Life Evaluation Method for Foundry Crane Metal Structure Considering Load Dynamic Response and Crack Closure Effect

“…Therefore, the impact effect of load increases during operation, which accelerates the crack propagation process and reduces the service life of welded joints. The specific calculation process of vertical impact coefficient 4 φ caused by track defects for a crane is described in Dong et al [Dong, Xu and Xin (2018)].…”

“…To further verify the accuracy, feasibility, and applicability of the proposed method, it is compared with the nominal stress method in Dong et al [Dong, Lu and Teng (2012)], hot spot stress method given in Li [Li (2014)], and Pairs model of fatigue crack growth without considering crack closure effect in Dong et al [Dong, Xu and Xin (2018)]. The results are shown in Tab.…”