Effect of crowning radius on rolling contact fatigue strength for traction drive elements (Evaluation by simulation)

Abstract

A simulation of the rolling contact fatigue strength of a traction drive element was developed. This simulation accounts for both the distribution of sizes of inclusions in the element material and the influence of traction forces at the element surface. The shear strength of the matrix structure surrounding an inclusion was estimated with an equation. The hardness distribution and the Weibull distribution of inclusion dimensions, which are necessary parameters to calculate the rolling contact fatigue strength, were determined by observation of an actual test specimen. The purpose of this report is simulations to evaluate the effect of the crowning radius on the rolling contact fatigue strength and the torque capacity. The simulations were carried out by varying the crowning radius of the virtual roller. To consider the effect of the crowning radius, a simulated two-dimensional virtual roller, which has actual material properties, was modified to a roller multilayered toward the axial direction. The simulation assuming the actual roller led to a difference of 1.0% from the experimental rolling contact fatigue strength. This difference was 2.4 points smaller than the result for the two-dimensional virtual roller. The rolling contact fatigue strength decreased with increasing crowning radius for two reasons. One was the increase in the number of inclusions under the high stress due to the increasing crowning radius. The other was the expansion of the portion of the roller subject to high stresses down to a depth having small hardness. However, the torque capacity calculated from the contact force resulting in failure increased with the increasing crowning radius.

Keywords

• machine element
• traction drive
• rolling contact fatigue
• inclusion
• tribology
• shear stress