Abstract
A computer program is developed to find the dynamic tooth load variation, make growth analysis of the crack at tooth fillet region, and determine the life of a spur gear in terms of load cycles. Variable amplitude-variable position cyclic load on the tooth is found by using a model based on torsional vibrations of gears. Stress intensity factor is determined by assuming small, through face width cracks. Paris-Erdogan crack growth rate equation is used for crack growth analysis. Load interaction effects are taken into consideration by using Willenborg retardation model. Stress intensity factor variation is arranged by using range-pair range cycle counting method. Rack cutter tip fillet radius and rack cutter geometry are taken into consideration in tooth modeling and rack cutters standardized by ISO are used for the analysis. Finite element method is used to find tooth stifnesses. Bending deformations of gear bodies and supporting shafts, bearing deformations, torsional deformations of gear bodies, and contact deformations of teeth are included in stiffness calculations.
