Increasing the bending fatigue resistance of spur gear teeth using a presetting process

Abstract

The fatigue life of machine elements may be increased if beneficial compressive residual stresses are introduced. One mechanical method of introducing compressive residual stresses is prestressing or presetting. This paper discusses the application of a presetting process to AISI 1040 steel spur gear teeth. Gear teeth were individually preset using a single tooth bending fatigue fixture. Subsequent fatigue testing with R=0.10 using the same fixture demonstrated that presetting increased the bending fatigue life by an average of 670% and 95% for fatigue under an applied maximum unit load of U L=216 MPa and 253 MPa, respectively. Finite element analyses were performed to model the application of the presetting process to spur gear teeth, enabling prediction of residual stress and permanent tooth deformation.