Analysis Of Switch Machine Crack Fatigue Life

Electric switch machine is an important equipment of switch transation in railway,its safe running time is an important index for evaluating fatigue life. With the rapiddevelopment of railway in our country, the load factor of switch machine is increased,the work busy degree is aggravated,and the switch machine accidents become more andmore frequently.According to analysise these accidents,many accidents are caused bystructure fatigue damage. All life include crack initiation life and crack propagationlifeTaking switch machine for example, the prediction research for fatigue damage wasmade. the following are the research work of this paper.The fatigue research at home and abroad was studied and basic theory of finiteelement analysis method were stdudied. Through the static analysis result, the partswhich produced crack easily were concluded;According to the fatigue type and LoadCharacteristics of switch machine,it concluded that the fatigue type was high cyclefatigue. According to its fatigue type and structure particularity, the fatigue crackinitiation life of the mental structure of switch machine’s action pole was estimatedbased on local stress-strain method. The data was made in rain flow counting method byusing Matlab programming and the cyclic stress-strain curve was drawed,the crackinitiation life of switch machine’s action pole was caculated according to the linearcumulative damage theory; The rain flow was count in nSoft fatigue analysis software,the stress spectrum was compiled and extrapolated in the process of the stress;Acoording to the hypothesis of such as Goodman Life curve, asymmetrical stresscycling of stress spectrum was converted to the asymmetrical stress cycling whosemean value is0, all levels’ stress cycling time was concluded.The crack initiationfatigue life was predicted and anylysed by using local stress-strain method in nSoft;therack propagation life of switch machine’s action pole was predicted by using the graysystem forecast method,and then it was estimated according to the Paris formula based on fracture mechanics.Finally,its predicted life were compared, the accuracy of the greysystem prediction was verified and the crack propagation life was concluded.