scholarly journals Stress corrosion in silica optical fibers: Review of fatigue testing procedures

2018 ◽  
Author(s):  
Irina Severin ◽  
Claudia Borda ◽  
Alexandru Dumitrache-Rujinski ◽  
Mihai Caramihai ◽  
Rochdi El Abdi
Keyword(s):  
Stress Corrosion ◽  
Optical Fibers ◽  
Fatigue Testing ◽  
Testing Procedures

Delayed Fatigue of Hydroxy- and Fluorhydroxyapatite Ceramics in Simulated Body Fluid

2005 ◽  
Vol 290 ◽  
pp. 366-369 ◽  
Author(s):  
Sergej M. Barinov ◽  
I.V. Fadeeva ◽  
L.V. Fateeva ◽  
S.V. Tumanov
Keyword(s):  
Stress Corrosion ◽  
Fatigue Testing ◽  
Ambient Air ◽  
Human Saliva ◽  
Strength Distribution ◽  
Dissociative Chemisorption ◽  
Weibull Statistics ◽  
Testing Data ◽  
Solvation Mechanisms ◽  
Harsh Conditions

Ultrafine hydroxyapatite (HA) and fluorhydroxyapatite (FHA) powders were synthesized and dense bioceramic samples were fabricated thereof. The samples were treepoint bend tested in different environments, i.e. in ambient air, distilled water and simulated human saliva, in the wide deformation rate range. Weibull’ statistics test was performed under standard testing conditions but in different media. The stress velocity exponent was evaluated from the dynamic fatigue testing data. The mean strength is shown to decrease when both ceramics are exposed to water or to simulated saliva. HA ceramics is more susceptible to the environment compared to FHA ceramics, due to the later is less subjected to the stress corrosion. Fracture surface observations revealed the crack propagation is of mixed trans- and intergranular mode. Strength distribution changes from uni-modal in air environment to bimodal in harsh conditions of water and saliva, indicating slow increment of flaw size in ceramics. Crack velocity exponent values correspond to transient region from dissociative chemisorption to ion solvation mechanisms of stress corrosion in both HA and FHA ceramics. Generally, FHA ceramics is considered to be much more reliable for application in bone defects replacement or dental reconstruction.

Resistance of 18Cr-18Ni-2Si Stainless Steel to Stress Corrosion Crack Propagation in Boiling Magnesium Chloride

CORROSION ◽  
1970 ◽  
Vol 26 (3) ◽  
pp. 95-98 ◽  
Author(s):  
J. A. DAVIS
Keyword(s):  
Stainless Steel ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
Magnesium Chloride ◽  
The Other ◽  
Test Results ◽  
Steel Composition ◽  
Testing Procedures ◽  
Resistance To Stress ◽  
Cold Worked

Abstract The propagation resistance of a steel cannot be determined by conventional testing procedures if the steel is resistant to crack initiation. Since conventional techniques were used to develop 18-18-2 stainless steel for resistance to stress corrosion cracking, its resistance to crack propagation was determined by means of pre-initiated cracks. Two laboratory heats of steel were prepared, one with the typical 18-18-2 stainless steel composition and the other with essentially the same composition but with high phosphorus and molybdenum contents, to make it susceptible to cracking. The steels were roll-bonded together and sheet specimens were prepared in the annealed, cold worked, and sensitized conditions. U-bend specimens were prepared, half of them with the susceptible steel on the tension side and the other half with the resistant steel on the tension side. The specimens were exposed in boiling magnesium chloride (150 C, 302 F). When cracks appeared, the specimens were retained in the solution for a minimum of 3 to 4 additional weeks to allow the cracks to propagate. No cracks initiated in 18-18-2 stainless steel under any of the conditions tested during five months of exposure. Cracks that initiated in the susceptible steel propagated to the interface and stopped. No cracks were observed that propagated into 18-18-2 stainless steel, even for specimens that cracked in 70 hours and were not removed for five months. These test results indicate that 18-18-2 stainless steel is resistant to crack propagation.

Development of Fatigue Testing of Full-Scale Girth Welded Pipes Under Variable Amplitude Loading

2011 ◽  
Author(s):  
Yan-Hui Zhang ◽  
Stephen Maddox
Keyword(s):  
Fatigue Limit ◽  
Fatigue Damage ◽  
Fatigue Testing ◽  
Full Scale ◽  
Cumulative Damage ◽  
Constant Amplitude ◽  
Variable Amplitude ◽  
Testing Procedures ◽  
Fatigue Design ◽  
Damage Rule

In service the great majority of structures and components are subjected to stresses of variable amplitude (VA). The fatigue design of welded joints in such structures is based on fatigue data obtained under constant amplitude loading, used in conjunction with a cumulative damage rule to estimate the damage introduced by cycles of varying magnitude in the service stress history. There are two major concerns with fatigue design of deepwater steel catenary risers (SCRs): the validity of cumulative damage rule and the damaging effect of stresses below the constant amplitude fatigue limit (CAFL). It is known that SCRs can experience very high numbers of low stress cycles due to vortex induced vibration (VIV) with the result that the choice of method for accounting for the fatigue damage due to stresses below the constant amplitude fatigue limit can be highly significant in terms of the estimated fatigue life. These two fundamental issues have been addressed in a recent group sponsored project. By successfully establishing a loading spectrum representative of that experienced by risers and developing the testing procedures for VA loading using the resonance testing rigs, the fatigue performance of full-scale girth welded pipes under VA loading were investigated. These loading spectra had the same peak/maximum stress histograms but different minimum stresses. Many tests lasted over 108 cycles to investigate the fatigue damage of small stresses in these spectra. This paper describes the development of the method by which fatigue testing of full-scale girth welded pipes under VA loading had been successfully performed.

scholarly journals Investigation on Fatigue Threshold Testing Methods in a Near Lamellar TiAl Alloy

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3487
Author(s):  
Shiyuan Wang ◽  
Hangyue Li ◽  
Paul Bowen
Keyword(s):  
Tial Alloy ◽  
Fatigue Testing ◽  
Fatigue Loading ◽  
Load Shedding ◽  
Fatigue Threshold ◽  
Threshold Values ◽  
Tial Alloys ◽  
Testing Procedures ◽  
Crack Wake ◽  
Electro Discharge Machining

The effects of influential fatigue testing factors, including loading schemes (e.g., traditional load shedding and staircase load increasing), morphology of crack starters, and precracking approaches on the near-threshold fatigue crack growth behaviors for a near lamellar γ-TiAl alloy (Ti-45Al-2Mn-2Nb-1B) were investigated at room temperature and 650 °C. The results showed that the measured fatigue threshold values in lamellar γ-TiAl alloys are very sensitive to the applied testing procedures. For example, the staircase load-increasing method yielded smaller threshold values. When such a load-increasing method was used, the threshold values were measured either from a notch machined by electro-discharge machining or prepared by a compression–compression fatigue loading. Moreover, some differences could be seen with respect to the morphologies of the crack starters. Most of the above influences are associated with the brittle nature of the material and the characteristics of the lamellar microstructures, and closure effects are primarily induced by crack wake roughness or unbroken ligaments.

Laser Peening without Coating to Mitigate Stress Corrosion Cracking and Fatigue Failure of Welded Components

2008 ◽  
Vol 580-582 ◽  
pp. 519-522 ◽  
Author(s):  
Yuji Sano ◽  
Yoshihiro Sakino ◽  
Naruhiko Mukai ◽  
Minoru Obata ◽  
Itaru Chida ◽  
...  
Keyword(s):  
Residual Stress ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Compressive Residual Stress ◽  
Fatigue Testing ◽  
Corrosion Cracking ◽  
Laser Peening ◽  
Alloy 600 ◽  
Metallic Materials ◽  
Laser Peening Without Coating

The authors have applied laser peening without coating (LPwC) to metallic materials. Compressive residual stress nearly equal to the yield strength of the materials was imparted on the surface. Accelerating stress corrosion cracking (SCC) tests showed that LPwC had a significant effect to prevent the SCC initiation of sensitized materials of SUS304, Alloy 600 and the weld metal, Alloy 182. Push-pull type fatigue testing demonstrated that LPwC drastically enhanced the fatigue strength of fillet-welded rib-plates of SM490A.

Investigation of Laboratory Fatigue Testing Procedures for Asphalt Aggregate Mixtures

1993 ◽  
Vol 119 (4) ◽  
pp. 634-654 ◽  
Author(s):  
James M. Matthews ◽  
Carl L. Monismith ◽  
J. Craus
Keyword(s):  
Fatigue Testing ◽  
Testing Procedures

Surface Films on Zircaloy-2 Samples Cracked in Neutral Aqueous NaCl by Stress Corrosion

1973 ◽  
Vol 31 ◽  
pp. 46-47
Author(s):  
R.A. Ploc
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Film Thickness ◽  
Stress Corrosion ◽  
Zirconium Dioxide ◽  
Surface Film ◽  
Surface Films ◽  
Continuous Layer ◽  
Transmission Electron ◽  
Product Film

Samples of low-nickel Zircaloy-2 (material MLI-788-see(1)), when anodically polarized in neutral 5 wt% NaCl solutions, were found to be susceptible to pitting and stress corrosion cracking. The SEM revealed that pitting of stressed samples was occurring below a 2000Å thick surface film which behaved differently from normal zirconium dioxide in that it did not display interference colours. Since the initial film thickness was approximately 65Å, attempts were made to examine the product film by transmission electron microscopy to deduce composition and how the corrosion environment could penetrate the continuous layer.

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