Surface Stress Concentration Analysis of Shot Peened Aluminium Alloys

2010 ◽  
Vol 449 ◽  
pp. 70-76
Author(s):  
J. Solis-Romero ◽  
J. Oseguera-Peña ◽  
J. Verduzco-Martínez ◽  
J. González-Sánchez
Keyword(s):  
Residual Stress ◽  
Stress Concentration ◽  
Surface Stress ◽  
Aluminium Alloys ◽  
Stress Gradient ◽  
Stress Effect ◽  
Surface Residual Stress ◽  
Closure Stress ◽  
Surface Crack Initiation ◽  
Effect Of Surface

Fatigue limit for surface crack initiation on shot peened Aluminium Alloys resulted to be determined by surface residual stress and stress concentration, according to the magnitude of the applied stress. The effect of surface roughness considered as micro-notches (dents) has been analysed by using the Vallellano and Navarro’s formulation. It was also determined that the stress gradient associated to those dents dominates over the closure stress effect.

Advanced Evaluation Methods of Residual Stress in Bioceramics Wear Surfaces

2010 ◽  
Vol 64 ◽  
pp. 43-48
Author(s):  
Giuseppe Pezzotti
Keyword(s):  
Residual Stress ◽  
Surface Stress ◽  
Electron Probe ◽  
Stress Fields ◽  
Fluorescence Probes ◽  
Surface Residual Stress ◽  
Hip Joints ◽  
Polycrystalline Alumina ◽  
Probe Size ◽  
F Center

Photo- and electro-stimulated probes have been employed for quantitatively evaluating highly graded residual stress fields generated at the surface of alumina hip joints. Optical calibrations revealed large differences in probe size, which strongly affected the detected magnitude of residual stress. A comparison between the responses of Raman and fluorescence probes in polycrystalline alumina showed that the depth of those probes spread to an extent in the order of the tens of microns even with using a confocal probe configuration. On the other hand, the electro-stimulated luminescence emitted by oxygen vacancy sites (F+ center) in the alumina lattice represented a suitable choice for confining to a shallow volume the stress probe. The electron probe enabled confining the measurement depth to the order of the tens of nanometers. Maps of surface residual stress were collected on both main-wear and non-wear zones of an alumina femoral head. A comparison among stress maps taken at exactly the same location, but employing different probes, clarified the averaging probe effects on surface stress magnitude.

Effects of Residual Stresses on the High Cycle Fatigue Behavior of Ti-6Al-4V

2010 ◽  
Author(s):  
Yu-Jia Li ◽  
Fu-Zhen Xuan ◽  
Zheng-Dong Wang ◽  
Shan-Tung Tu
Keyword(s):  
Residual Stress ◽  
Fatigue Limit ◽  
Stress Ratio ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
X Ray Diffraction ◽  
Surface Residual Stress ◽  
Manufacturing Techniques ◽  
Stress Ratios ◽  
Effect Of Surface

Axial force-controlled fatigue tests are conducted at various stress ratios (R) on Ti-6Al-4V specimens prepared by two different manufacturing techniques (hard turning plus polishing with and without vacuum stress relieve anneal carried out after polishing). Residual stress is measured by using X-ray diffraction. Results indicate that the surface compressive residual stress lead to an increase of fatigue limit at a given life and stress ratio. This effect decreases with increasing stress ratio R. At R = 0.6, the effect of surface residual stress on fatigue limit fades away. In addition, the location of crack initiation shifts from surface to interior when the stress ratio changes from −1 to 0.6.

The Influence of Surface Residual Stress on Fatigue Limit of Titanium

1960 ◽  
Vol 82 (1) ◽  
pp. 76-78 ◽  
Author(s):  
E. C. Reed ◽  
J. A. Viens
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Limit ◽  
Experimental Error ◽  
Endurance Limit ◽  
Simple Equation ◽  
Surface Residual Stress ◽  
A Value ◽  
Effect Of Surface

Investigation of the effect of surface residual stress on the endurance limit of 6Al 4V titanium alloy shows that this effect is equal within experimental error to the residual stress divided by a constant. Results can be expressed by a simple equation. A value for the constant has been derived.

Role of Quantitative NDE Techniques in Life Management of Gas Turbine Components

2006 ◽  
Author(s):  
Michael Gorelik ◽  
Waled T. Hassan ◽  
Harry Kington
Keyword(s):  
Residual Stress ◽  
Stress Gradient ◽  
Surface Residual Stress ◽  
Major Barrier ◽  
Near Surface ◽  
Life Management ◽  
Surface Residual Stresses ◽  
Engine Components ◽  
Nondestructive Measurements ◽  
Non Destructive

A number of earlier publications discussed the benefits of probabilistic analysis and probabilistic lifing in application to critical rotating engine components. One of the important variables in both probabilistic and deterministic lifing analysis is the level of residual stress in the component. Near surface residual stresses directly influence the fatigue life of critical engine rotating components. Depending on sign and magnitude a near surface residual stress gradient can either inhibit or accelerate fatigue initiation and crack propagation. A major barrier to introducing subsurface residual stress information into the life calculation process is the necessity to make accurate and reliable nondestructive measurements on as produced hardware. The paper reviews several NDE technologies that could be candidates for both production and in-service non-destructive residual stress measurements. The importance of having accurate residual stress information and its use in the probabilistic design and life management process is illustrated on several examples. A linkage with several ongoing industry R&D programs is discussed.

scholarly journals Effect of surface residual stress and inclusion size on fatigue failure mode of matrix HSS in very high cycle regime

2010 ◽  
Vol 2 (1) ◽  
pp. 873-882 ◽  
Author(s):  
Yuuji Shimatani ◽  
Kazuaki Shiozawa ◽  
Takehiro Nakada ◽  
Takashi Yoshimoto
Keyword(s):  
Residual Stress ◽  
Failure Mode ◽  
Fatigue Failure ◽  
Inclusion Size ◽  
Surface Residual Stress ◽  
Very High ◽  
Effect Of Surface
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