A Rudimentary Analysis of Improving Fatigue Life of Metals by Shot-Peening

In this paper, a rudimentary analysis of improving fatigue life of metals is presented. The process is viewed as one of repeated impact of a stream of hard shots on to a target. The model considers first a single shot impinging upon a target and, on bouncing, it leaves a residual stress below the surface of the target. The problem is then generalized to consider the effect of a stream of shots by assuming their effect to be uniformly distributed over the entire surface. The analysis is highly simplified and it mainly aims at understanding the mechanics of this complicated process. Although rudimentary, the theoretical analysis is seen to be in reasonable agreement with experimental results performed with shots on targets of various materials.

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Experimental and Simulation Method of Introducing Compressive Residual Stress in ASTM A516 Grade 70 Steel

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.803.27 ◽

2019 ◽

Vol 803 ◽

pp. 27-31

Author(s):

Mohd Rashdan Isa ◽

Saiful Naim Sulaiman ◽

Omar Suliman Zaroog

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Surface Treatment ◽

Shot Peening ◽

Compressive Residual Stress ◽

Tensile Loading ◽

Simulation Method ◽

Single Shot ◽

Equivalent Amount ◽

Simulation Procedure

Compressive residual stress below the surface of material could increase fatigue life as it encounters the tensile loading applied on the material during operation. Shot peening process is a common surface treatment to introduce this stress. This study will investigate on how to introduce the same amount of residual stress by simulation using FEM as introduced in experimental shot peening process. Actual shot peening process was done using a particular sets of parameters and FEM with single shot is used to simplify the simulation procedure. Result shows that using a single shot simulation could also introduce the equivalent amount of residual stress as in the experimental multi-shots shot peening process. This value could be used in further study to study the relaxation of the stress after load is being applied.

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Shot Peening Effects on Subsurface Layer Properties and Fatigue Performance of Case-Hardened 18CrNiMo7-6 Steel

Advances in Materials Science and Engineering ◽

10.1155/2018/3795798 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

H. S. Ho ◽

D. L. Li ◽

E. L. Zhang ◽

P. H. Niu

Keyword(s):

Fatigue Life ◽

Shot Peening ◽

Fatigue Testing ◽

Subsurface Layer ◽

Fatigue Performance ◽

Single Shot ◽

Depth Study ◽

Enhanced Properties ◽

Integrity Analysis ◽

The Way

The present study is conducted with a dual-aim: firstly, to examine the effect of several single shot peening conditions on the subsurface layer properties and fatigue performance of the case-hardened 18CrNiMo7-6 steel, and secondly, to propose an optimized peening condition for improved fatigue performance. By carrying out the subsurface integrity analysis and fatigue testing, the underlying relationships among the peening process, subsurface layer property and fatigue performance are investigated, the way peening conditions affect the fatigue life and its associated scatter for the case-hardened 18CrNiMo7-6 steel is quantitatively assessed. The in-depth study shows that dual peening can be an optimized solution, for it is able to produce a subsurface layer with enhanced properties and eventually gain a significant improvement in fatigue performance.

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Influence of Residual Stress on the Thermal Expansion Behavior of Electroformed Nickel Layers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.662.511 ◽

2013 ◽

Vol 662 ◽

pp. 511-514

Author(s):

Yi Chun Liu ◽

Jia Min Zhang ◽

Jian Hong Yi

Keyword(s):

Heat Treatment ◽

Residual Stress ◽

Thermal Expansion ◽

Theoretical Analysis ◽

Subsequent Heat Treatment ◽

Experimental Results ◽

Thermal Expansion Behavior ◽

Expansion Behavior ◽

Electroformed Nickel ◽

The Relationship

Nickel layers with tensile or pressure residual stress were prepared by electroforming technique from two kinds of electrolyte. Subsequent heat treatment was adopted to get the stress released. The coefficients of thermal expansion (CTEs) were measured with a thermal dilatometer and the relationship between residual stress and the measured CTEs was revealed both from experimental results and theoretical analysis.

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Investigation on Theoretical Analysis of Residual Stress Distribution Induced by Shot Peening in 2397 Aluminum-Lithium Alloy

Lecture Notes in Mechanical Engineering - Advanced Surface Enhancement ◽

10.1007/978-981-15-0054-1_7 ◽

2019 ◽

pp. 56-68

Author(s):

Yukui Gao ◽

Xuefei Tao

Keyword(s):

Residual Stress ◽

Stress Distribution ◽

Theoretical Analysis ◽

Shot Peening ◽

Residual Stress Distribution ◽

Lithium Alloy ◽

Aluminum Lithium Alloy ◽

Aluminum Lithium

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Influence of Different Surface Treatments on Fatigue Life of 7050 Al Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.944.142 ◽

2019 ◽

Vol 944 ◽

pp. 142-148 ◽

Cited By ~ 4

Author(s):

Nan Li ◽

Hai Tao Li ◽

Jing Yi Zhou ◽

Hong Tao Liu ◽

Chang Kui Liu ◽

...

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Fracture Surface ◽

Surface Morphology ◽

Surface Analysis ◽

Shot Peening ◽

Surface Treatments ◽

Al Alloy ◽

Stress Measurements ◽

Fracture Surface Analysis

The fatigue life of 7050 Al alloy samples after different surface treatments, i.e., as-machined, anodizing, shot peening, and shot peening followed by anodizing, had been tested. The shot peening treatment specimens presented the longest average fatigue life. The fatigue life of anodizing treatment specimens decreased by 69.3% and 78.8% at 215 MPa and 260 MPa stress levels than as-machined ones. Introducing the shot peening treatment before anodizing can increase the fatigue life by 220% / 296.9% at 215 MPa/260 Mpa than that only treated by anodizing. The effect of the surface treatments on the fatigue life were studied by performing surface morphology investigation, residual stress measurements and fracture surface analysis.

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A Study on the Fatigue Characteristics of Al6061-T651 by Shot Peening Velocity

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.1093 ◽

2006 ◽

Vol 326-328 ◽

pp. 1093-1096 ◽

Cited By ~ 1

Author(s):

Won Jo Park ◽

Sun Chul Huh ◽

Sung Ho Park

Keyword(s):

Residual Stress ◽

Surface Roughness ◽

Fatigue Life ◽

Shot Peening ◽

High Speed ◽

Compressive Residual Stress ◽

Velocity Increase ◽

Fatigue Characteristics ◽

Height Increase ◽

Small Steel

Small steel ball is utilized in Shot peening process. Called “shot ball” are shot in high speed on the surface of metal. When the shot ball hit the surface, it makes plastic deformation and bounce off, that increase the fatigue life by compressive residual stress on surface. In this study, the results of observation on the tensile strength, hardness, surface roughness, compressive residual stress and fatigue life of a shot peened Al6061-T651 were obtained. Experimental results show that arc height increase tremendously by shot velocity. Also, it shows that surface roughness, hardness, compressive residual stress and fatigue life increase as shot velocity increase.

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A Study on the Improvement of Durability of Gear Steel by Shot Peening

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.321-323.662 ◽

2006 ◽

Vol 321-323 ◽

pp. 662-665 ◽

Cited By ~ 1

Author(s):

Dong Sun Lee ◽

Tae Hyung Kim ◽

Jae Heon Lee ◽

Tae Kun Lee ◽

Seong Kyun Cheong

Keyword(s):

Residual Stress ◽

Fatigue Life ◽

Shot Peening ◽

Compressive Residual Stress ◽

Spur Gear ◽

Sem Image ◽

Gear Steel ◽

Ball Velocity ◽

Bending Fatigue Test ◽

Fatigue Characteristics

In this paper the fatigue life of spur gear was investigated by changing the shot peening condition. From bending fatigue test depending on various shot peening intensity, fatigue characteristics were investigated. The causes of reduction in fatigue life were analyzed by observing the surface of gear with Scanning Electron Microscope(SEM), and impact of residual stress to fatigue characteristics was identified by measuring compressive residual stress depending peening intensity by depth. The results show that the optimum shot ball velocity is 65 m/s and optimum peening time is 8 minutes. From SEM image, the micro-crack was observed at the surface in case of over peening. This seems to be the factor which reduces fatigue life by decreasing compressive residual stress of surface.

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NUMERICAL SIMULATION FOR SHOT-PEENING BASED ON SPH-COUPLED FEM

International Journal of Computational Methods ◽

10.1142/s0219876211002782 ◽

2011 ◽

Vol 08 (04) ◽

pp. 731-745 ◽

Cited By ~ 4

Author(s):

JIANMING WANG ◽

FEIHONG LIU

Keyword(s):

Residual Stress ◽

Shot Peening ◽

Compressive Residual Stress ◽

Target Material ◽

Material Model ◽

Single Shot ◽

Fem Modeling ◽

Contact Algorithm ◽

Particle Hydrodynamics ◽

Smoothed Particle

In dealing with shot-peening simulation, existing literatures adopt finite element method (FEM), which establishes models of a single shot or several shots only, thus the effect of a large number of shots repeat impacting and the influence among adjacent shots are ignored. To overcome these disadvantages of FEM models, smoothed particle hydrodynamics (SPH)-coupled FEM modeling is presented, in which the shots are modeled by SPH particles and the target material is modeled by finite elements. The two parts interact through contact algorithm to simulate a number of shots impinging the target. Utilizing this model, a material model for shots is established, the relationships between compressive residual stress and peening frequencies, coverage, and velocities are analyzed. Steady compressive residual stress can be obtained by multiple peening; higher coverage can improve the compressive residual stress; faster velocities can induce greater and deeper maximum residual stress in target subsurface. The simulation results agree well with the existing experimental data. The study would not only provide a new powerful tool for the simulation of shot-peening process, but also be benefit to optimize the operating parameters.

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The Effect of Inclined Loads on the Large Deflection Behaviour of Elastoplastic Work-Hardening Straight and Pre-Bent Cantilevers

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/pime_proc_1995_209_128_02 ◽

1995 ◽

Vol 209 (2) ◽

pp. 87-96 ◽

Cited By ~ 8

Author(s):

J H Liu ◽

A G Atkins ◽

A J Pretlove

Keyword(s):

Elastic Modulus ◽

Theoretical Analysis ◽

Work Hardening ◽

Reasonable Agreement ◽

Large Deflection ◽

Plastic Region ◽

Experimental Results ◽

Modulus Ratio ◽

Inclined Loads

A theoretical analysis is presented to examine the effect of inclined tip load on the large deflection behaviour of an elastoplastic cantilever with linear work hardening. The cantilever is either initially straight or pre-bent to a tip angle of ø (see Fig. 1). When the load is large enough, the overall deformation of a pre-bent cantilever is smaller than that of an initially straight one as a result of the influence of the guided end. The maximum plastic region spm in the cantilever increases with the force angle ø and the plastic-elastic modulus ratio α, but decreases as the beam flexibility parameter β increases. Some unstable deformation may occur in the initially straight cantilever when ø > π/2 and this depends on the value of α and β. Reasonable agreement is obtained between the theoretical analysis and experimental results.

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