Analytical and Numerical analysis of fatigue life estimation of the splined shaft by using Finite Element Method

Abstract

The splined shaft is a significant component in the power plant and automobile industries because it performs two functions: it acts as an anti-rotational device or transmits torque to another device. This study deals with the splined shaft of the Howo 336 HP dump truck, which exists at the end of the driveshaft to transmit the torque with its version of the splines (i.e., splined hub) through a connection between involute spline contact faces. When con tinuous torque operation occurs, the stress becomes maximum at those contact surfaces, which leads to micro-pitting failures and reduces the fatigue life of the component. There fore, various parameters leading to the initiation of such pits have been determined because once the flank surface fails, it cannot be restored and easily made for re-manufacturing to be reused again. To analyze them, both splines’ CAD models (shaft and hub) were designed by Solid Work 2020 Premium based on the ANSI B92.1 involute spline manual, and the numerical simulation was done by ANSYS Workbench 19.2. Thus, the Hertz contact stress equation was used to calculate the influence of contact stresses under various flank surface loading conditions for the surface affecting factors called coefficient of friction, surface fa tigue strength factor, and surface finishing process with its roughness. As a result, with a minimum variation of 5.9 %, the contact stress in an involute splined shaft agrees with the analytical contact stress calculated by Hertz stress. So, surface contact stress increases with higher friction in the area of contact and better surfaces that have less roughness, resulting in high fatigue strength. The results showed that when the surface load increases the surface fatigue life will decrease for given initial surface roughness. Meanwhile, on the analysis of the surface manufacture process due to the allowable fatigue life cycle for the various load ing conditions, the mirror polished surface finishing process has high cycle fatigue among them. Then, within this surface finishing process, the flank surface of the fatigue life of the component can be improved.