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Article
Publication date: 30 August 2011

Yoshihiro Sakino, Yuji Sano and You‐Chul Kim

Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this…

Abstract

Purpose

Laser peening without coating (LPwC) is an innovative surface enhancement technology for introducing compressive residual stress in metallic materials. The purpose of this study is to examine the characteristic at the laser‐peened welded zone and the fatigue lives of the welding joints.

Design/methodology/approach

LPwC conditions for 490 MPa grades of structural steels were selected. By using the conditions, the characteristic at the laser‐peened welded zone, residual stresses, hardness and roughness of welding toes were examined. Moreover, the fatigue lives of the toes of box‐welded joints and butt welded joints pre‐treated by LPwC were compared to the fatigue lives of those that were not pre‐treated by LPwC.

Findings

The main results are: LPwC conditions for 490 MPa grade steels were established; residual stresses, Vickers hardness and roughness at the laser‐peened welded zone were revealed; and LPwC can dramatically extend the fatigue life of welded joint.

Originality/value

The effects of LPwC on structural steels, which are widely used in bridge members, have not been well clarified; the effect of LPwC on welded zones in these structures is particularly unclear. If LPwC can be carried out such that compressive residual stress is imparted on structural steels and the welded zones in the bridge members, the fatigue lives of bridge members will be greatly increased. The paper fills some of these gaps.

Details

International Journal of Structural Integrity, vol. 2 no. 3
Type: Research Article
ISSN: 1757-9864

Keywords

Article
Publication date: 31 May 2011

Lothar Wagner, Mansour Mhaede, Manfred Wollmann, Igor Altenberger and Yuji Sano

The purpose of this paper is to investigate the influence of mechanical surface treatments on the surface layer properties and the fatigue performance of the aircraft…

1280

Abstract

Purpose

The purpose of this paper is to investigate the influence of mechanical surface treatments on the surface layer properties and the fatigue performance of the aircraft alloys Al 7075‐T73 and Ti‐6Al‐4V

Design/methodology/approach

Laser peening without coating (LPwC), shot peening (SP), ultrasonic shot peening (USP) and ball burnishing (BB) were applied and the resulting changes in surface roughness and residual stress‐depth profiles were evaluated. Fatigue performance of both alloys was tested in rotating beam loading (R=−1) on hourglass‐shaped specimens and the results were compared with the electrolytically polished (EP) reference conditions.

Findings

All studied mechanical surface treatments led to pronounced increases in fully reversed fatigue lives and fatigue strengths in both Al 7075‐T73 and Ti‐6Al‐4V.

Originality/value

To the authors' knowledge, this is the first paper that compares fatigue performance of a wide variety of mechanically surface treated conditions in two aircraft alloys.

Details

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

Keywords

Article
Publication date: 8 March 2011

Yuji Sano, Koichi Akita, Kazuya Takeda, Rie Sumiya, Toshiyuki Tazawa, Toshiyuki Saito and Chihiro Narazaki

The purpose of this paper is to investigate the behavior of compressive residual stress induced by laser peening under external loading on an age‐hardened high‐strength…

Abstract

Purpose

The purpose of this paper is to investigate the behavior of compressive residual stress induced by laser peening under external loading on an age‐hardened high‐strength aluminum alloy A2024‐T3, a low‐carbon austenitic stainless steel SUS316L (Type 316L) and a nickel‐based alloy NCF600 (Alloy 600).

Design/methodology/approach

The surface residual stress was measured intermittently by X‐ray diffraction during cyclic uniaxial loading.

Findings

The compressive residual stress due to laser peening significantly decreased during the first few cycles at stress ratio of 0.1 with the maximum loading stress exceeding the 0.2 per cent yield stress. No remarkable decrease was observed afterward until the end of the loading cycles.

Originality/value

Under symmetric loading at the stress ratio of −1 to A2024‐T3, a major decrease took place in the compression side of the first loading cycle. The surface residual stresses remained in compression within all the extent of the present experiments, even if the maximum loading stress exceeded the yield stress of the materials.

Details

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

Keywords

Content available

Abstract

Details

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

Article
Publication date: 1 February 2000

Yaw A. Debrah and Ian G. Smith

Presents over sixty abstracts summarising the 1999 Employment Research Unit annual conference held at the University of Cardiff. Explores the multiple impacts of…

10871

Abstract

Presents over sixty abstracts summarising the 1999 Employment Research Unit annual conference held at the University of Cardiff. Explores the multiple impacts of globalization on work and employment in contemporary organizations. Covers the human resource management implications of organizational responses to globalization. Examines the theoretical, methodological, empirical and comparative issues pertaining to competitiveness and the management of human resources, the impact of organisational strategies and international production on the workplace, the organization of labour markets, human resource development, cultural change in organisations, trade union responses, and trans‐national corporations. Cites many case studies showing how globalization has brought a lot of opportunities together with much change both to the employee and the employer. Considers the threats to existing cultures, structures and systems.

Details

Management Research News, vol. 23 no. 2/3/4
Type: Research Article
ISSN: 0140-9174

Keywords

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