Prediction Fatigue Life of Dumpers with Cumulative Fatigue Damage Approach and Finite Element Model

Abstract

Fatigue damage of damper increases with applied load cycles in a cumulative manner. Cumulative fatigue damage analysis plays a key role in life prediction of components and structure of dumpers subjected to field load histories. In order to investigate the fracture reasons of some components of coal dumper installed at Qinhuangdao Port, some field measurements of strain and stress were carried out. The field measurement data shows that the first principal stress of structure is less than limited strength of applied material and stress concentration problem has distinct affection to stress distribution for some components. The loading spectrums acted on dumpers are created according to measured strain data in field. The finite element model is meshed for assessing and calculating stress distribution and strength characteristics of dumpers. The stress distribution and stress concentration factors of main components of dumper at different loading cases are numerically simulated. A fatigue damage model is developed for evaluating accumulative fatigue damage of dumpers. The Ramberg-Osgood equation is used for constructing cyclic stress-strain relation. Fatigue damage indexes and service life are calculated by a modified Palmgren-Miner rule and finite element model. The investigation shows that fatigue notch factor and stress concentration factor have a significant influence on the calculation of fatigue damage of dumpers. The numerical simulation for fatigue calculation of dumper shows that prediction results of fatigue life agreed good with practical life.