A FEM-Based 2D Model for Simulation and Qualitative Assessment of Shot-Peening Processes

Abstract

Shot peening is one of the most favored surface treatment processes mostly applied on large-scale engineering components to enhance their fatigue performance. Due to the stochastic nature and the mutual interactions of process parameters and the partially contradictory effects caused on the component’s surface (increase in residual stress, work-hardening, and increase in roughness), there is demand for capable and user-friendly simulation models to support the responsible engineers in developing optimal shot-peening processes. The present paper contains a user-friendly Finite Element Method-based 2D model covering all major process parameters. Its novelty and scientific breakthrough lie in its capability to consider various size distributions and elastoplastic material properties of the shots. Therewith, the model is capable to provide insight into the influence of every individual process parameter and their interactions. Despite certain restrictions arising from its 2D nature, the model can be accurately applied for qualitative or comparative studies and processes’ assessments to select the most promising one(s) for the further experimental investigations. The model is applied to a high-strength steel grade used for automotive leaf springs considering real shot size distributions. The results reveal that the increase in shot velocity and the impact angle increase the extent of the residual stresses but also the surface roughness. The usage of elastoplastic material properties for the shots has been proved crucial to obtain physically reasonable results regarding the component’s behavior.

Stress-Shot-Peened Leaf Springs Material Analysis through Nano- and Micro-Indentations

“…This is an outstanding achievement for these industrial applications, when considering the total absence of data regarding the elastoplastic properties of decarburized HTT and SSPaffected surface zones of suspension components. A further major benefit of the availability of such curves is their immediate usage within FEM-based SSP simulation models [5] to provide sound understanding of the SSP phenomena occurring in the components' surface zones and increase the overall SSP simulation accuracy. The exercised work-hardening on the surface layers as an outcome of the severe deformation imposed by the SSP process is herein quantified in a tangible and measurable way, enabling the yield of conclusions with industrial importance and the development of realistic computational models to predict the life span.…”

“…Over the past two decades research activities were focused on the SSP simulations to elaborate optimal and reproducible processes. Unfortunately, this knowledge has so far failed to be successfully transferred to suspension components, mainly because the material properties acting at the failure-critical decarburized surface (a) are very difficult to be obtained accurately at a local level and (b) often differ significantly from those of the core [5]. Due to these handicaps and the multi-parametric and very complex technical nature of the involved manufacturing procedures, the process optimization is still a laborintensive task that relies on individual experience and requires many experimentation loops.…”

Investigation of the Shot Size Effect on Residual Stresses through a 2D FEM Model of the Shot Peening Process

“…Pre-studies showed that an element length less than 20 µm may slightly improve the accuracy but increases the required computational time significantly. Further extensive information and thorough descriptions regarding the model characteristics are available in [20].…”

“…The elastoplastic material properties for both shots and specimen are depicted from [20] and presented in Table 1. Alongside the fundamental elastic-plastic material properties, a simple linear isotropic hardening rule was applied that also considers strain rate effects, as described in the study of Maliaris et al [20].…”

“…Despite the progress made, crucial questions regarding the elastoplastic shot material behavior and the influence of shot size distributions have not been adequately addressed. Recently, a 2D FE model has been developed [20], using a plane strain approach similar to [13], capable of covering the aforementioned issues with sufficient accuracy. It considers elastoplastic material properties for the shots and real shot size distributions, a combination of properties that is also only present in [21], where the authors presented an extended study on the deviations of shot diameter.…”