Crack Propagation Analysis And Fatigue Life Prediction Of Spur Gears Tooth Root

Gear is the most commonly driving part used in area of aerospace, automotive and energy, whose failure will not only brings certain economic losses, but also can lead to major safety accident. The tooth alignment uneven distribution of load is considered in the process of actual meshing in order to truly reflect root crack propagation process. The process of crack growth, in different tooth alignment load, is simulated by FRANC3 D software, then K factors and crack growth life are given out.The results are comparatively analyzed to get the influence of load uneven distribution on the process crack propagation.The main research contents and results are as follows:( 1) The program which is used to establish gear model is written by using ANSYS APDL language. Considering the symmetry of gear tooth, one of the gear teeth is took as the research objectin in order to reduce the amount of calculation.Crack initiation location is determined through the statics analysis, and the initial crack is inset in the location.(2)Actually, loads, on different points on the contact line, are not equal in the process of gears meshing. Linear changing load along contact line length is applied on gear. The process of crack growth, under the load, is simulated by using FRANC3 D software, then the stress intensity factors and the crack deflection angles are calculated. The process of crack growth is compared with process under the working of ideal uniformly distributed load. The results show that, in the process of crack growth, the actual values of the stress intensity factors and the crack deflection angles are bigger than the ideal values; under working of the actual load and the ideal load,the crack growth paths have a great difference.( 3) The crack growth life, under the action of the ideal and actual load, is predicted by using the energy release rate criterion and Paris formula. The results point out that the tooth alignment load uneven distribution shortens the life of crack growth, which leads to shortening gear fatigue life.( 4) The location of initial crack has important influence on the crack growth life. Crack growth life is predicted in the situation of different angles, which are 15 o,30o, 45 o and 60 o, made by initial crack plane and addendum plane. The results indicate that the fatigue crack growth life is proportional to the angle.