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Article
Publication date: 1 August 1999

David Kirk

Discusses the use of a corporate Internet in a geographically‐spread consulting firm, James Martin & Co., to share ideas, vision, client information and results…

Abstract

Discusses the use of a corporate Internet in a geographically‐spread consulting firm, James Martin & Co., to share ideas, vision, client information and results. Illustrates with examples. Applications include a quarterly Employee Attitude Survey and regular discussion forums. Proposes that a well‐designed corporate intranet is a highly effective method of making intangible vision and mission pledges more tangible.

Details

Aircraft Engineering and Aerospace Technology, vol. 71 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 1 April 1995

Roger Brickwood

Controlled shot peening is widely accepted in the aerospace industry for fatigue life enhancement of critical aeroengine and airframe components. Less well known and…

Abstract

Controlled shot peening is widely accepted in the aerospace industry for fatigue life enhancement of critical aeroengine and airframe components. Less well known and little understood by many production engineers is the associated process of “peen forming”. This uses the basic principle of shot peening to form or shape curved sheet metal geometries which would be difficult to create with conventional methods such as die bending, stretch‐forming or rolling. It is particularly cost effective where the number of components involved is too small to justify expensive mass production processes.

Details

Aircraft Engineering and Aerospace Technology, vol. 67 no. 4
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 5 October 2015

Georgios Savaidis, Stylianos Karditsas, Alexander Savaidis and Roselita Fragoudakis

The purpose of this paper is to investigate the fatigue and failure of commercial vehicle serial stress-peened leaf springs, emphasizing the technological impact of the…

Abstract

Purpose

The purpose of this paper is to investigate the fatigue and failure of commercial vehicle serial stress-peened leaf springs, emphasizing the technological impact of the material, the thermal treatment and the stress-peening process on the microstructure, the mechanical properties and the fatigue life. Theoretical fatigue analysis determines the influence of each individual technological parameter. Design engineers can assess the effectiveness of each manufacturing process step qualitatively and quantitatively, and derive conclusions regarding its improvement in terms of mechanical properties and fatigue life.

Design/methodology/approach

Two different batches of 51CrV4 were examined to account for potential batch influences. Both specimen batches were subjected to the same heat treatment and stress-peening process. Investigations of their microstructure, hardness and residual stress state on the surface’ areas show the effect of the manufacturing process on the mechanical properties. Wöhler curves have been experimentally determined for the design of high-performance leaf springs. Theoretical fatigue analyses reveal the influence of every above mentioned technological factor on the fatigue life of the specimens. Therewith, the effectiveness and potential for further improvement of the manufacturing process steps are assessed.

Findings

Microstructural analysis and hardness measurements quantify the decarburization and the degradation of the specimens’ surface properties. The stress-peening process causes significant compressive residual stresses which improve the fatigue life. On the other hand, it also leads to pronounced surface roughness, which reduces the fatigue life. The theoretical fatigue life analysis assesses the mutual effect of these two parameters. Both parameters cancel each other out in regards to the final effect on fatigue life. The sensitivity of the material and the potential for further improvement of both heat treatment and stress peening is appointed.

Research limitations/implications

All quantitative values given here are strictly valid for the present leaf spring batches and should not be widely applied. The results of the present study indicate the sensitivity of high-strength spring steel used here to the various technological factors resulting from the heat treatment and the stress-peening process. In addition, it can be concluded that further research is necessary to improve the two processes (heat treatment process and the stress peening) under serial production conditions.

Practical implications

The microstructure investigations in conjunction with the hardness measurements reveal the significant decrease of the mechanical properties of the highly stressed (failure-critical) tensile surface. Therewith, the potential for improvement of the heat treatment process, e.g. in more neutral and controlled atmosphere, can be derived. In addition, significant potential for improvement of the serially applied stress-peening process is revealed.

Originality/value

The paper shows a systematic procedure to assess every individual manufacturing factor affecting the microstructure, the surface properties and finally, the fatigue life of leaf springs. An essential result is the quantification of the surface decarburization and its influence on the mechanical properties. The methodology proposed and applied within the theoretical fatigue life analysis to quantify the effect of technological factors on the fatigue life of leaf springs can be extended to any engineering component made of high-strength steel.

Details

International Journal of Structural Integrity, vol. 6 no. 5
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 1 February 2002

K. Han, D.R.J. Owen and D. Peric

Because of the unrealistic demand of computer resources in terms of memory and CPU times for the direct numerical simulation of practical peen forming processes, a…

Abstract

Because of the unrealistic demand of computer resources in terms of memory and CPU times for the direct numerical simulation of practical peen forming processes, a two‐stage combined finite/discrete element and explicit/implicit solution strategy is proposed in this paper. The procedure involves, at the first stage, the identification of the residual stress/strain profile under particular peening conditions by employing the combined finite/discrete approach on a small scale sample problem, and then at the second stage, the application of this profile to the entire workpiece to obtain the final deformation and stress distribution using an implicit static analysis. The motivation behind the simulation strategy and the relevant computational and implementation issues are discussed. The numerical example demonstrates the ability of the proposed scheme to simulate a peen forming process.

Details

Engineering Computations, vol. 19 no. 1
Type: Research Article
ISSN: 0264-4401

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Article
Publication date: 8 March 2011

Kelly S. Carney, Omar Hatamleh, James Smith, Thomas Matrka, Amos Gilat, Michael Hill and Chanh Truong

The purpose of this paper is to present an analytical framework for predicting the residual stresses that result from the laser shock peening of a friction stir‐welded…

Abstract

Purpose

The purpose of this paper is to present an analytical framework for predicting the residual stresses that result from the laser shock peening of a friction stir‐welded 2195 aluminum alloy sample, using the finite element software LS‐DYNA.

Design/methodology/approach

The pressures resulting from the laser peening are directly applied in an explicit transient analysis as forces. At the completion of the transient analysis, an implicit springback analysis is performed to determine the final residual stresses. This cycle is repeated for the appropriate number of peen applications, including the appropriate overlap of application areas. To validate the analytical framework, a comparison of residual stresses between analysis and a test specimen is made using laser‐peened base material which was not friction stir‐welded. Friction stir welding (FSW) causes residual stresses and material property variations. In this work, the varying material properties regions are simplified and defined as discrete, separate materials. The residual stresses resulting from the welding are introduced directly as initial conditions in the peening transient analysis and so are combined within the analysis with the residual stresses from the peening.

Findings

Comparisons made between the experimental and analytical residual stresses are generally favorable.

Originality/value

Analysis of the laser shock peening of FSW has not been accomplished previously.

Details

International Journal of Structural Integrity, vol. 2 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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Article
Publication date: 11 November 2014

Keiji Houjou, Koji Takahashi, Kotoji Ando and Hisanori Abe

– The purpose of this paper is to investigate the effect of peening on the fatigue limit of steels for welded structure with a crack in the weld toe zone.

Abstract

Purpose

The purpose of this paper is to investigate the effect of peening on the fatigue limit of steels for welded structure with a crack in the weld toe zone.

Design/methodology/approach

An artificial semi-circular slit was created in the weld toe, and peening was conducted. Then, bending fatigue tests were carried out.

Findings

First, owing to the shot peening, the maximum slit depths that can be rendered harmless were 1.0 and 1.2 mm in SUS316 and SM490, respectively. Second, during the fatigue test, the fracture of a peened specimen originated outside the slit, which indicated that peening eliminated the effect of the slit on the fatigue limit. Third, the fatigue limit of a slit specimen was improved by the enhanced residual stress distribution and the decreased stress concentration due to plastic deformation at the weld toe.

Originality/value

There are very few studies about which a fatigue crack is rendered harmless by residual compressive stress, as a result the structures could be continued to use. Moreover, the study defining the concept about rendering crack harmless and systematic investigation was not able to be found.

Details

International Journal of Structural Integrity, vol. 5 no. 4
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 1 July 1965

A FIVE‐AXIS contouring‐type numerically‐controlled shot peening machine has solved the problem of strengthening certain critical structural components of the General

Abstract

A FIVE‐AXIS contouring‐type numerically‐controlled shot peening machine has solved the problem of strengthening certain critical structural components of the General Dynamics F.111 variable sweep wing tactical fighter/bomber which is being built at Fort Worth for the United States Navy, the United States Air Force, the Royal Australian Air Force and, possibly, for service with the Royal Air Force. Apart from the vital wing support assembly which must carry the entire weight of the aircraft during flight, over thirty other F.111 components are automatically shot peened with absolute uniformity in this tape‐controlled machine to give the necessary fatigue strength—among the components being 25 ft. long milled wing skins.

Details

Aircraft Engineering and Aerospace Technology, vol. 37 no. 7
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 31 May 2011

Goran Ivetic

The aim of this paper is to give a simple and accurate tool for prediction and comparison of residual stresses in laser shock peened and shot peen treated materials.

Abstract

Purpose

The aim of this paper is to give a simple and accurate tool for prediction and comparison of residual stresses in laser shock peened and shot peen treated materials.

Design/methodology/approach

This work applies finite element code ABAQUS in order to compare the residual stress state and plastic deformation in specimens in aluminium alloy 7050‐T7451, treated with shot peening (SP) and laser shock peening (LSP) processes. Both processes are simulated using the Hugoniot elastic limit (HEL) of the material in question, and the processes are modelled using same input parameters (pressure on the surface of the specimen and the duration of contact between the material and the peening medium).

Findings

By using the same approach in both the analyses, a sound comparison of two technologies can be made, by comparing the obtained residual stress profiles. In addition, surface pressure and contact time can be varied easily in a parametric analysis, allowing the calibration of the numerical results.

Research limitations/implications

Owing to simplicity of used numerical models, different process parameters relative to SP process have not been taken in consideration directly, but through their effect on pressure on the surface of the specimen and the duration of contact between the material and the peening medium.

Originality/value

Application of HEL material model, usually applied to LSP problems, to the analysis of SP process gives promising results, in spite of simplicity of used numerical model.

Details

International Journal of Structural Integrity, vol. 2 no. 2
Type: Research Article
ISSN: 1757-9864

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Article
Publication date: 1 October 1975

The one‐step precision blasting method of glass bead cleaning, peening and corrosion removal involves impelling micron size spherical glass particles at controlled…

Abstract

The one‐step precision blasting method of glass bead cleaning, peening and corrosion removal involves impelling micron size spherical glass particles at controlled velocities against a work‐piece. The impact of the glass beads on the surface of the object pulverises and removes all forms of oxidation, corrosion and other foreign matter, including pit corrosion and corrosion in recessed and hidden areas around and under items such as rivets, The removal of all foreign matter down to the base metal is accomplished far more rapidly, hence far more economically, than currently utilised methods. There is no removal of base metal, no dimensional change and no contamination. Peening is achieved in a similar manner, as will be described later.

Details

Aircraft Engineering and Aerospace Technology, vol. 47 no. 10
Type: Research Article
ISSN: 0002-2667

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Article
Publication date: 2 February 2015

Anoop Vasu and Ramana V. Grandhi

The impact of laser peening on curved geometries is not fully comprehended. The purpose of this paper is to explain the action of laser peening on curved components…

Abstract

Purpose

The impact of laser peening on curved geometries is not fully comprehended. The purpose of this paper is to explain the action of laser peening on curved components (concave and convex shapes for cylindrical and spherical geometries) by means of shock wave mechanics.

Design/methodology/approach

An analytical formulation is derived based on the plasticity incurred inside the material and the results are compared with the prediction by numerical simulation.

Findings

A near-linear relationship is observed between curvature and compressive residual stress; an increasing trend was observed for concave models and a decreasing trend was observed for convex models. The consistency in the analytical formulation with the simulation model indicates the behavior of laser peening for curved geometries.

Originality/value

The differences observed in the residual stresses for spherical and cylindrical geometries are primarily due to the effect of Rayleigh waves. This paper illustrates the importance of understanding the physics behind laser peening of curved geometries.

Details

International Journal of Structural Integrity, vol. 6 no. 1
Type: Research Article
ISSN: 1757-9864

Keywords

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