Spelling suggestions: "subject:"fretting corrosion"" "subject:"retting corrosion""
21 |
Fretting fatigue damage accumulation and crack nucleation in high strength steelsPape, John Andrew 05 1900 (has links)
No description available.
|
22 |
An analysis of fretting fatigueNowell, D. January 1988 (has links)
This thesis describes a series of fretting fatigue experiments carried out under closely controlled conditions of partial slip. These experiments confirm the existence of a size effect whereby the fretting fatigue life of an aluminium alloy is shown to vary with contact size. The configuration chosen, of cylindrical fretting pads contacting a plane specimen is amenable to classical stress analysis and the surface tractions between the contacting bodies are derived. The effects of tension in the specimen, finite specimen thickness, differing elastic constants, and surface roughness are all investigated and incorporated into the analysis where appropriate. A technique is then developed to calculate stress intensity factors for plane cracks growing under the contact load at an arbitrary angle to the free surface. The analysis is then applied to the experimental results and three possible explanations for the size effect are proposed, based on statistical effects, crack arrest, and crack initiation. These are examined in the light of the experimental evidence and it is proposed that the variation of fatigue life with contact size is due to an increase in the amount of fretting damage above a threshold level for crack initiation. A composite parameter is chosen to characterise the severity of fretting conditions and this is shown to describe the experimental results accurately. Finally, the use of this parameter in design calculations is discussed.
|
23 |
Corrosion and Fretting Corrosion Studies of medical grade CoCrMo implant material in a more clinically relevant simulated body environment.Ocran, Emmanuel Kofi 27 May 2014 (has links)
In modular hip implants, micro-motion, which leads to fretting corrosion at the head/neck and neck/stem interfaces, has been identified as a major cause of early revision in hip implants, particularly those with heads larger than 32mm. It has been found that the type of fluid used to simulate the fretting corrosion of biomedical materials is crucial for the reliability of laboratory tests. Therefore, to properly understand and effectively design against fretting corrosion damage in modular hips, there is the need to replicate the human body environment as closely as possible during in-vitro testing and validation. In this work, corrosion behavior of CoCrMo in 0.14 M NaCl, phosphate buffered saline (PBS) and clinically relevant simulated body fluid (sbf) is carried out. Also, fretting corrosion studies of the CoCrMo alloy in a clinically relevant novel simulated body fluid (sbf) environment is studied. The presence of phosphate ions in PBS accounted for the higher corrosion rate when compared with 0.14 M NaCl and sbf environment. Despite the low and comparable corrosion rates in 0.14 M NaCl and sbf, the nature of the protective passive film formed in sbf shows the suitability of the novel sbf for future corrosion and fretting corrosion analysis. Finally, the influence of micro-motion at the modular head/neck and neck/stem interfaces on the concentration of metallic ions that goes into the synovial fluid and surrounding tissues is reported.
|
24 |
A molecular dynamics modeling study on the mechanical behavior of nano-twinned Cu and relevant issuesYue, Lei. January 2010 (has links)
Thesis (M. Sc.)--University of Alberta, 2010. / Title from pdf file main screen (viewed on July 15, 2010). A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Materials Engineering, Department of Chemical and Materials Engineering, University of Alberta. Includes bibliographical references.
|
25 |
Signal Analysis of Fretting Damages on Electrial Connector SystemsXING, YASHAN, XU, WEILONG January 2017 (has links)
Electrical connectors are widely utilized for signal communications in automotive electronic systems whose performance is related to the reliability of the entire system. Electrical connectors are frequently affected by the engine vibration, resulting in fretting damages on electrical connector. In this thesis, the main propose is to find a signal analysis method to predict the fretting damages on fuel pump connector induced by engine vibration. The data of the fuel pump connector is studied from a vibration test of the four-cylinder engine and the dominating frequencies are used in the fretting test to verify the analysis method. The fretting damage is identified through visual inspection by microscope. The model of the connector is built in COMSOL to explain the fretting on the contact surfaces. The results present the signal analysis method can be directly used to predict the risk of fretting damages during the engine vibration. Some significant frequencies are pointed out as guidelines for future tests and optimization.
|
26 |
Fundamental studies of the tribological behavior of thin polymeric coatings in fretting contact using infrared and photo/video techniquesGhasemi, Hamid-Reza M. R. 04 October 2006 (has links)
Direct measurements of surface temperatures produced during fretting contact are an unknown area in the discipline of tribology; in addition, the possible effects of such temperatures on the behavior of protective anti-fretting coatings (e.g., polymeric) have never been investigated. An oscillating contact device was designed and built to study fretting contact behavior in tribological processes. The contact geometry consisted of a stationary spherical test specimen loaded against a vibrating sapphire disk driven by an electromagnetic shaker. Surface temperatures generated by frictional heating were measured during fretting contact using an infrared microscope. A photo/video technique was developed to view the fretting contact interface during an experiment and to measure the size and distribution of real area(s) of contact. The effects of size and distribution of the areas on the experimental surface temperatures for polymer-coated steel spheres-on- sapphire were investigated. Archard's theoretical model was also modified to account for multiple contact areas, and the calculated surface temperatures were compared to the experimental results.
Polymeric coatings - including polystyrene (PS), polymethylmethacrylate (PMMA), polysulfone (PSO), polyvinylchloride (PVC), and polyvinylidenechloride (PVDC) were studied at a given load (20 N), frequency (150 Hz), amplitude (100 JLm), and film thickness (55 p.m). The surface temperatures generated were generally low and below the glass transition temperatures of the rigid polymers studied. The magnitude of the surface temperatures was found to be particularly dependent on the size and distribution of real area(s) of contact. The most extensive studies were performed using polystyrene coatings. Effects of load, frequency, amplitude, and film thickness on surface temperature rise and the size and distributions of real area of contact were examined. In addition, uncoated steel specimens were studied under various loads and fretting amplitudes. The observed formation of iron oxide at low surface temperature (60°C) tribologica1 experiments was explained in terms of exoelectron emission.
There were considerable differences observed in the behavior of polymeric coatings under various fretting conditions. The fretting behavior of the coatings was explained in terms of mechanical and thermo-elastic effects. Thermo-elastic predictions of size distributions of real contact areas (patches) showed good agreement with the observed photo/video studies. A mechanism was proposed for tribological behavior and fretting protection of polystyrene coatings. / Ph. D.
|
27 |
Moisture and stress effects on fretting between steel and polyimide coatingsKang, Chiun-Chia 06 June 2008 (has links)
Fretting of solvent cast polyimide coatings was investigated in a ball-on-flat geometry as a function of relative humidity. Polyimides were synthesized from benzophenone tetracarboxylic dianhydride (BTDA) and bisanline (Bis P), 6-fluoro bis dian hydride (6FDA) and Bis P, and pyromellitic dianhydride (PMDA) and bis A phenyl phosphine oxide (BAPPO). Coating life - the time for the steel ball to wear through the coating - shortened with increasing humidity. Iron oxides or other reaction products from 52100 ball generated at high humidity acted as abrasives and accelerated the wear of the coatings. Variation of coating life among the three polyimides was attributed to the residual stress, which developed upon cooling from the annealing temperature due to the mismatch of thermal expansion coefficients between the polymer and the metal substrate. Calculated from elasticity theory, the normal stress dropped shortly after the start of the test, remained relatively constant, and increased toward the end. This variation correlated with the wear rate and accounted for the non-linear increase of coating life with coating thickness. Sub-surface shear stress and surface tensile stress predicted well, respectively, the debonded shape and the inter-crack spacing of Hertzian cracks. / Ph. D.
|
28 |
Friction and degradation of rubber coatings under fretting conditionsVeyret-Abran, Christophe 21 July 2010 (has links)
A fundamental study was conducted to analyze the friction and degradation mechanisms of thin rubber coatings used as fretting corrosion inhibitors. Two elastomers, polyurethane and styreneethylene-butylene (SEBS), were investigated. The mechanisms of wear were studied by analyzing wear scars with optical microscopy. Friction mechanisms were investigated using friction forcedisplacement hysteresis loops and friction force variation with test frequency, fretting amplitude and fIlm thickness. Lastly, coating life variation with these three parameters was studied and explained through a simplified fatigue mechanics approach. / Master of Science
|
29 |
A vibration analysis of a bearing/cartridge interface for a fretting corrosion studyElliott, Kenny B. (Kenny Blair) January 1981 (has links)
M.S.
|
30 |
The effect of film thickness on the behavior of polystyrene-coated steel disks under fretting conditionsRaciti, Romolo January 1987 (has links)
The purpose of this study was to evaluate the effect of film thickness on a polystyrene coating used to prevent fretting corrosion in a steel-on-steel system. The polystyrene coating was applied to a 1045 steel disk and fretted against a 52100 steel ball. Two sets of experiments were employed. The first set evaluated film life by using seven different film thicknesses ranging from 7.9 to 52 um. The results from this set of experiments indicated that a drastic increase in film life occurred for coatings thicker than 40 pm. The other set of experiments was used to study how fretting damage progressed with time and how it was affected by film thickness. For this purpose two film thicknesses, 38 and 52 μm, were used. The results from these experiments led to the speculation that stress and temperature conditions were different in the 38 and 52 μm films. These differences resulted in a milder fretting regime, and therefore longer life, in the thicker film. Optical and scanning electron microscopy and computer graphics were used to study in detail the fretting interface. The fretting mechanisms were explained in terms of mechanical, chemical, tribochemical, and tribophysical effects. / Master of Science
|
Page generated in 0.0675 seconds