Fatigue on Shot‐Peened Gears: Experimentation, Simulation and Sensitivity Analyses

Abstract

The present paper deals with fatigue experimentation and with the application and improvement of predictive models; in addition, a sensitive analysis is performed on the main factors related to the shot‐peening treatment and on the efficiency of the aforementioned models. The research involved gears, made of high‐strength steel and carburised, quenched, ground, shot‐peened and superfinished. The experimental campaign initially dealt with the investigation into the influence of isotropic superfinishing; the attention was then focused on shot peening and how to optimise the fatigue limit, by a suitable choice of operative parameters. The option of duplex peening for further fatigue improvement was also considered. Results concerning component residual stress distributions and fatigue limits were then processed by investigating their sensitivity with respect to driving factors, namely the shot diameter and the Almen intensity. Two theories for fatigue prediction (the method of the relative stress gradient and the theory of critical distances) were reviewed for application to shot‐peened components, with a comparison between experimental and numerical results. A comparative analysis was then performed on the two theories, on the basis of the number of data inputs, advantages and drawbacks, while sensitivity analyses focused on how uncertainties affecting input data propagate to predictive results.

Enhanced fatigue behavior of powder metallurgy Ti–6Al–4V alloy by applying ultrasonic impact treatment

“…At the same time, it should be noticed that the used approach did not take the high residual stress field formed by the UIT process and/or other surface thermo-mechanical treatments into explicit consideration. It was recently suggested that the whole stress distribution within surface layer should be taken into account for the fatigue prediction of the shot-peened components containing high residual stresses, and the role of mean stress for this method must be treated by running an iteration procedure [58].…”

Influence of Shot Peening Parameters on Residual Stresses in Flake and Vermicular Cast Irons

“…4-6) deviates from the classical distribution found for shot peening which often display subsurface compressive stress peak [11,13,14]. Other shapes of residual stress curves, e.g.…”

“…with a surface stress plateau, were also found in the literature but less common. Some of the non-classical stress distributions could be related to multi-peening [14,15] or peening induced phase transformation [4]. Measurements on steels of different yield strengths [16] showed that the strength of the target material can also be important.…”

High Spatial Resolution Evaluation of Residual Stresses in Shot Peened Specimens Containing Sharp and Blunt Notches by Micro-hole Drilling, Micro-slot Cutting and Micro-X-ray Diffraction Methods

“…Bagherifard et al [11] tried to predict the fatigue resistance of peened notched parts measuring RSs far from the notch, thus neglecting the perturbation exerted by the notch on the RS field in terms of intensity and mono-or multi-axiality. Laboratory XRD measurements were taken on the root of peened notches [24][25][26][27][28], but the millimeter size of the irradiated area impeded to resolve the lateral gradient of the RS distribution. King et al [29] used energy dispersive synchrotron XRD to measure inplain residual strains at the root of the notch of shot peened samples.…”