Numerical Stress Concentration Analysis of a Driven Gear Tooth Root With Two Fillet Radius

Daniela Ristić

Determining an optimal gear form relative to stress concentration is one of the main problems of gear design. Gear carrying capacity largely depends on main gear profile configuration parameters. The tooth root form and fillet radius have a great influence on gear tooth root strength which is primarily discussed in this paper. Special attention is given to the analysis of the impact of the gear tooth fillet radius at the critical cross section on stress values and distribution. The stress intensity factor and the gear working life depend directly on tooth root stress. It is known that a first initial crack appears on a gear tooth most affected by root stress concentration. Hence, this research was focused on finding an optimal fillet tooth root radius to minimize the tooth root stress intensity. However, in order to get a lower tooth root stress concentration value, one more fillet radius is involved as a “disencumber notch” [3]. In this paper a special attention will be dedicated to stress concentrations in a gear tooth root with two, instead of only one fillet radius (“two level approach“ in a root). This paper provides the results achieved by the application of numerical methods - the finite element method (FEM) and the real working conditions simulation. The results are analyzed in order to form an effective numerical model for tooth root geometrical discontinuity phenomena at static loading. Although tooth root critical stress conditions were analysed for both driving and driven gears of one real transmitter, this paper presents the stress results only for the driven gear for both fillet radii ρ_F1 and ρ_F2.

FUL TEXT

Scientific Technical Review , No.3-4, 2009