Residual Stress and Fatigue Strength of Metals

Kodama, Shotaro

doi:10.1299/jsmemag.75.642_1026

Cited by 19 publications

(15 citation statements)

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“…This reduces the misfit and thereby the residual stress during the compressive part of the first cycle (see figure 23). Cao et al (1994) building on the work by Kodama (1972) identified two distinct stages for the relaxation. The first stage has been termed previously 'elastic shakedown' and it occurs over the first loading cycle in figure 23.…”

Section: Pre-stretching/stress Levelling and Shakedownmentioning

confidence: 99%

Residual stress and its role in failure

2007

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Our safety, comfort and peace of mind are heavily dependent upon our capability to prevent, predict or postpone the failure of components and structures on the basis of sound physical principles. While the external loadings acting on a material or component are clearly important, There are other contributory factors including unfavourable materials microstructure, preexisting defects and residual stresses. Residual stresses can add to, or subtract from, the applied stresses and so when unexpected failure occurs it is often because residual stresses have combined critically with the applied stresses, or because together with the presence of undetected defects they have dangerously lowered the applied stress at which failure will occur. Consequently it is important that the origins of residual stress are understood, opportunities for removing harmful or introducing beneficial residual stresses recognized, their evolution in-service predicted, their influence on failure processes understood and safe structural integrity assessments made, so as to either remove the part prior to failure, or to take corrective action to extend life. This paper reviews the progress in these aspects in the light of the basic failure mechanisms.

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Section: Pre-stretching/stress Levelling and Shakedownmentioning

confidence: 99%

Residual stress and its role in failure

2007

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“…However, this situation is unlikely to occur in engineering components where both mean stress and stress ratio vary according to location within component. Logarithmic functions (based on experimental observation) such as that of Kodama 97 (equation ( 6)) are valid after the initial quasi static relaxation; however, it is typically this first relaxation which is most significant in components. A new model for the ratio of residual stress after N cycles s rsN to initial residual stress s rs0 , was developed 95 (equation (7)) which was able to account for both quasi static relaxation and logarithmic softening and which was dependent on stress amplitude s a , R s and number of cycles N as the controlling parameters.…”

Section: Interaction Between Shot Peening Induced Residual Stresses A...mentioning

confidence: 99%

Life assessment methodologies incoroporating shot peening process effects: Mechanistic consideration of residual stresses and strain hardening Part 1 – effect of shot peening on fatigue resistance

Soady

2013

Materials Science and Technology

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Shot peening is a well known process applied to components in order to improve their fatigue resistance. In recent years, there has been an increasing interest in including the effects of the shot peening process in life assessment models since this would allow a reduction in conservatism compared to those in current application. The present paper seeks to review firstly the effects of the shot peening process (surface roughening, strain hardening and compressive residual stresses) and how the magnitude of these effects can be determined both experimentally and numerically. The reasons for the beneficial effect of shot peening on fatigue resistance are reviewed; this includes consideration of how different operating conditions can affect the magnitude of the benefit. The second part of the review details the life assessment approaches which have been developed to date incorporating these effects and seeks to identify the areas in which further development is still required before the models can be applied in structural integrity assessments.

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“…However, the relief of the residual stress was not generated when a single compression stress was applied even if a single compression stress of 400 MPa was applied. In general, it is reported that the relief of the compressive residual stress during a fatigue test is generated when the absolute value obtained by adding an applied stress to a compressive residual stress exceeds the absolute value of the compressive yield stress of the material (26) . As for DI, Ochi et al reported that the residual stress of FPDI was relieved when the above condition was satisfied (27) .…”

Section: ×mentioning

confidence: 99%

Evaluation of Fatigue Strength of Ductile Cast Iron Composed of Ferrite-pearlitic Structures with As-cast Surfaces (Effect of Surface Roughness, Microstructure Transition Layers, Defects and Residual Stress on Fatigue Strength)

Yamabe¹,

Kobayashi²,

Nakajima³

2007

JMMP

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In order to elucidate the complex effects of surface roughness, the transition of microstructures from the surface to the interior, defects and residual stress, tension-compression fatigue tests have been conducted by using shot blasted ferrite-pearlite ductile cast irons with as-cast surfaces. Regardless of the applied stress levels, the fracture origins of the specimens were mostly situated at a defect near an as-cast surface, slag, or pinhole at N f < 10 7. At a relatively lower stress amplitude, some fatigue fractures such as shrinkage occurred from an inner defect far from the surface, mostly at N f > 10 7. The area parameter model was applied to the quantitative evaluation of the fatigue limit. The equivalent hardness considering the transitional layers and the effective defect size with the interaction between the surface roughness and a defect were defined. Moreover, the relief of the residual stress during the fatigue tests was detected. The mean value of the relieved residual stress acting on a defect was employed for the quantitative evaluation. By using these parameters, the complex effects of ductile cast iron have been successfully evaluated for practical use.

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Residual Stress and Fatigue Strength of Metals

Cited by 19 publications

References 0 publications

Residual stress and its role in failure

Residual stress and its role in failure

Life assessment methodologies incoroporating shot peening process effects: Mechanistic consideration of residual stresses and strain hardening Part 1 – effect of shot peening on fatigue resistance

Evaluation of Fatigue Strength of Ductile Cast Iron Composed of Ferrite-pearlitic Structures with As-cast Surfaces (Effect of Surface Roughness, Microstructure Transition Layers, Defects and Residual Stress on Fatigue Strength)

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