A NEW MODEL FOR THE NUMERICAL DETERMINATION OF FITTING RESISTANCE OF GEAR TEETH FLANKS

A numerical model for determining the pitting resistance of gear teeth hanks is presented in this paper. The model considers the material fa tigue process leading to pitting, i.e. the conditions required for cra ck initiation and then simulation of fatigue crack propagation. The th eory of dislocation motion on persistent slip bands is used to describ e the process of crack initiation, where the microstructure of a mater ial plays a crucial role. The simulation of crack growth takes into ac count both short crack growth, where the modified Bilby, Cottrell and Swinden model is used for simulation of dislocation motion, and long c rack growth, where the theory of linear elastic fracture mechanics is applied. The stress field in the contact area of meshing spur gear tee th and the functional relationship between the stress intensity factor and crack length are determined by the finite element method. For num erical simulations of crack initiation and crack propagation in the co ntact area of spur gear teeth, an equivalent model of two cylinders is used. On the basis of numerical results, and with consideration of so me particular material parameters, the service life of gear teeth flan ks is estimated. The developed model is applied to a real spur gear pa ir, which is also experimentally tested. The comparison of numerical a nd experimental results shows good agreement and it con be concluded t hat the developed model is appropriate for determining the pitting res istance of gear teeth flanks.