The Steel Structure Fatigue Life Research Of Crane Beam In Service

In recent years,according to a survey of crane beam,the industrial construction crane beam has so much complexity of the stress that the steel crane beam under reciprocating load will appear different degree of fatigue cracks.It can endanger the safety of production and reduce the economic benefit.Therefore,the fatigue life of the crane beam structure is an important index to control the security which the fatigue life research can effectively prevent and reduce the damage probability and can be extended for life.At present,both at home and abroad have not been able to precisely to predict the fatigue life of crane beam.Therefore,chosen a better evaluation methods for fatigue life become very necessary.This article adopts two methods which are the traditional fatigue life estimation and DFR for fatigue life estimation.First of all,using all known parameters of the crane beam set up a 3D model by ANSYS finite element software which start Static analysis and extract nine nodes' data which get the stress time history curve and displacement time history curve.Then we need find out the location of the maximum stress value node.Using structural mechanics knowledge find out absolute maximum bending moment.Eventually we should determine the position of the dangerous point compared the results from the ANSYS software with the results of structural mechanics.And then,into the transient analysis of ANSYS software,we set up three working conditions and extract time load history data.Through using the rain flow count method for classification statistical counting,we can obtaine load amplitude.By using weibull distribution formula,we can get the cycle of large load values,fit curve and load spectrum.And then calculate the stress spectrum by the theoretical formula.Finally,we adopt the DFR method that calculate the fatigue life which has 2.11 million times;Set up stress S-N curve by stress spectrum and use the Miner cumulative damage criterion with the fitting curve formula calculate the fatigue life which has 2.63 million times.Then comparing the analysis result we can get after the DFR method is more precise and the fatigue life of traditional method for estimating the fatigue life is too conservative.