Influence of typical loading errors on the effective loading characteristics of a gear bending fatigue test rig

Abstract

Loading errors in gear bending fatigue tests may alter tooth root stress distribution and reduce the consistency of test results. This study develops a finite element model of a gear bending fatigue test rig to evaluate the influence of typical loading errors on effective loading characteristics. A theoretical stress benchmark was first established based on the standard calculation method for gear bending strength. Under a single-tooth load of 25 kN, the theoretical tooth root bending stress was 838.25 MPa, while the maximum stress obtained from the error-free finite element model was 841.1 MPa, with a difference of approximately 0.3%. In addition, DIC-based experimental validation was conducted under the same nominal loading condition. The DIC-measured and finite element-predicted maximum principal strain distributions along the characteristic path were both mainly within 0.37%–0.43%, confirming that the model can reasonably capture the strain concentration characteristics of the tooth root region. Three typical errors, namely tooth trace installation error, lateral displacement error, and center rotation error, were then introduced to compare their effects on maximum tooth root stress, stress distribution along the tooth width, and high-stress region location. The results show that tooth trace installation error causes biased load distribution along the tooth width, while lateral displacement error changes the actual loading position. These two errors are the dominant factors affecting effective loading characteristics. In contrast, center rotation error only produces limited local disturbance within the investigated range. The results provide guidance for clamping positioning, loading error control, and improving the repeatability of gear bending fatigue tests.