| The thesis selected the output shaft gear of a certain loader's gearbox as the study object,the method for gear's parametric modeling and the technology that draw the tooth-root crack defects into gear's FEA model were studied deeply.The nonlinear contact finite element analysis and the fatigue analysis method were used to study how the tooth-root crack effect to the gear's stress distribution,and the equivalent life was defined as a working cycle,probe the method which can obtain the criterion of the tooth-root crack's limit parameter.First of all,according to the standard involute equation,analysis the parameter description form for the involute,and then the gear's 3D geometrical modeling was established by using UG soft's parametric modeling function.Secondly,the maximum equivalent stress under the worst load location was obtained by using the nonlinear contact finite element analysis method.Then,according to the 30°tangent dangerous section theory that put forward by Hofer,draw the crack defects into gear's FEA model in tooth-root dangerous section,and analysed by FEA method to study the rule of the maximum equivalent stress in gear change with crack parameter.At last,according to the fatigue analysis theory of Miner,the gearbox's output shaft gear's fatigue life was analyzed,based on the material's S-N curve and the gear pair's load spectrum,then use the converse illation method obtain the maximum equivalent stress which made the recycled gear scrap,obtained the critical parameter of tooth-root crack to judge if the recycled gear reach the requirement for next work cycle's using by comparing.The results showed that,the put forward of the tooth-root crack's limitcriterion for recycled gear,provide the test basis for the recycled gear's remanufacturing.At the same time,this method can also be used to provide reference for the the remaining life judgment in the other parts remanufacturing process. |
PDF Full Text Request