Effect Of Loading Condition On Fatigue Life Of Three-Support Shaft

Structural stiffness and strength properties of three supporting shaft are excellent,and be able to meet the design requirements of the machinery and equipment, and beused in a wide range of applications. However, due to statically indeterminateproblem of the support shaft, its working condition becomes very complex, andfatigue life problems of three supporting shaft become serious.In this paper the three supporting shaft is regarded as research object.First, Byusing the ANSYS parametric language APDL the finite element model of the threesupport shafts,gears and bearings are established,cutting force, gear forces andbearing displacement load is loaded, finite element analysis on the three-bearingspindle components is done and drew all kinds of the results of the stress and strainunder load conditions; Secondly, according to the method of coordinatetransformation, damage point the critical surface location and maximum damagevalue were calculated based on shear-type injury FS fatigue prediction model andprediction model based on stretch-type injury of the SWT fatigue; Finally, accordingto two types of fatigue life prediction equation and the alculated maximum damagevalue to calculate the three supporting shaft fatigue life under various load conditionsand obtained the variation of the fatigue life.By the study of the above calculation shows that: under the same cuttingparameters, the three supporting shaft fatigue life decreases as the load increases inthe rate of change before the critical speed faster, slower change after the criticalspeed. Add different displacement loading conditions three supporting shaft at thethree supporting and three supporting shaft fatigue life reduced with the increase ofthe load and the positive load sensitivity, this sensitivity with the increase of the loadweakened the middle of the displacement of the support load on the fatigue life, aftersupport followed, the former support the minimum. Stretch model to calculate thefatigue life than the shear-type model to calculate the fatigue life is higher, thedamage parameter can be drawn from the three supporting shaft fatigue critical planestrain is larger than the influence of the shear strain.