Fault analysis of spur gear using XFEM

Abstract

Spur gears are the most common and simplest in the geometric visualization, and are used to transmit motion and torque from the engine to the desired locations at different transmission ratios. Since the gears work in high loading conditions over a long period, the study of the gear faults due to the high stresses becomes important. In this study, the stresses generated at the root of the gear teeth due to bending is determined using finite element method (FEM) and validated analytically using Lewis theory. Further a detailed crack propagation analysis has been conducted with two intermediate backup ratios of 0.8 and 1.5 and allowing the initial crack length to vary as 0.125, 0.4, 0.7 and 1 mm and check the behavior of the crack propagation paths in static as well as dynamic loading conditions. Also the crack propagation path of the initial crack is observed at the orientations of 180° and 225° from the positive x-axis. The analysis shows that as the initial crack length increases there is increase in the stresses been generated. Further for both backup ratios of 0.8 and 1.5 it has been observed that the crack propagation paths shows variation as the initial crack length increases for both static and dynamic loadings and causes a shift from propagating through the rim to propagation into the width of the rim and showing vertical as well as horizontal propagation in higher initial crack lengths.