Bending Fatigue Strength of Gears under Various Loading Conditions

Abstract

In this paper, the authors investigated the bending fatigue properties and the behaviour of residual stress generated on the root fillet under the loading conditions corresponding to repeatedly reversed gears and idle gears, by using the bending fatigue testing machine of new type, which was developed by the authors. The main results obtained from this experiment are summarised as follows. (1) The bending fatigue limit of repeatedly reversed gears increases with the number of load cycles in one loading stage n. And there exists a linear relationship between σ_up"and log₁₀n. (2) The bending fatigue limit of idle gears decreases by about 40% compared with that in one side loading conditions. (3) In repeatedly reversed gears, compressive residual stress is generated on the root fillet of the load application side and tensile residual stress on that of the opposite side alternately, with the periodical change in the direction of load application. And in idle gears, compressive residual stresses are generated by alternating load on both sides of the root fillet.