Paper XVI (iv) Effect of Traction Fluid on Rolling Contact Fatigue Life of Thermally Refined Steel

Kato

et al. 2014

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.

Section: Effect Of Crowning Radius On Rolling Contact Fatigue Strengtmentioning

confidence: 99%

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

Kato

et al. 2014

“…Many kinds of fatigue tests have been carried out on rollers and balls to examine the influence of failure mechanisms, operating conditions, lubrication modes, roller materials, etc., on fatigue strength (Machida et al, 1993;Deng et al, 1999;Nakajima and Mawatari, 2005;Matsuo et al, 1991;Coy et al, 1981;Rohn et al, 1981). Murakami (2002) proposed an equation for predicting the fatigue limit, which considers the size of microdefects or inclusions.…”

Section: Introductionmentioning

confidence: 99%

Simulation of rolling contact fatigue strength for traction drive elements (comparison with fatigue test)

Kazama

et al. 2018

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 purpose of this report is verifying the estimation accuracy of this simulation by comparing with the experimental result. The experiment was carried out by according to the 14 S-N testing method. The material of test rollers was carburized JIS SCM420H. The hardness distribution and the Weibull distribution of inclusion dimensions, which are necessary parameters of this simulation, were determined by observation of an actual test specimen. The calculated rolling contact fatigue strength in failure rate of 50% at 10 7 cycles was 750 MPa with a standard deviation of 35.4 MPa. The rolling contact fatigue strength of 1120 MPa with a standard deviation of 50.8 MPa was obtained as a result of experiment. The failure mode was considered to be flaking from the internal origination. The calculated standard deviation was about equal to the experimental result. Though there was 370 MPa difference between calculated and experimental fatigue strength. Including of the hardening of roller and the influence of compressive residual stress in the simulation and the determination of the depth of failure initiation will decrease above error.

Simulation of Rolling Contact Fatigue Strength for Traction Drive Elements

Kazama

et al. 2013

A simulation of the rolling contact fatigue strength of a traction drive element was proposed. The simulation can account 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 were necessary parameters to calculate the rolling contact fatigue strength, were determined by observation of an actual test specimen. And the rolling contact fatigue strength was compared with the distribution of shear stresses in a roller affected by traction forces. A simulation assuming the same traction coefficient as that in the experiment predicted a rolling contact fatigue strength of 810 MPa with a standard deviation of 39.2 MPa, which differed from the experimental value by only 2.5%. Simulations of the rolling contact fatigue strength were then carried out while varying the traction coefficient. The contact force resulting in failure was observed to fall as the traction coefficient increased and the torque capacity increased. Thus, the torque capacity increases with the traction coefficient, regardless of changes in the rolling contact fatigue strength.