engleski

Residual Stresses in Gear Tooth Root

Short– time overloads in meshing gears can cause low– cycle fatigue damage in material, which means nucleation and accumulation of damage in gear tooth. In this paper the material behavior in low– cycle fatigue regime is characterized by material model that includes isotropic and kinematic hardening and/or softening and damage occurrence and accumulation. The material parameters for chosen material model are identified for the steel 42CrMo4 in normalised state with hardness of 296 HV and tempered state with hardness of 420 HV and 546 HV. The spur involute gear tooth is discretized by using finite element method with elements that have integrated these material parameters. The material response in tooth root under cyclic loading and occurrence and evolution of damage are analyzed. When the gear tooth is overloaded and stresses in material exceed the yield stress, the material deforms plastically on the tooth root fillet surface and under the tooth root fillet. As a consequence, the residual stresses appear in the tooth root after the load relaxation. The tooth root stresses in following load cycles tend to decrease because of the residual stresses and because of the material softening behaviour.

Low– cycle fatigue; Residual stresses; Spur gear

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