Showing papers on "Fatigue limit published in 1982"
TL;DR: The problem associated with short crack growth, defined as situations in which the intensity of the crack tip field is underestimated by linear elastic fracture mechanics analyses, is briefly reviewed in this paper.
Abstract: — The problem associated with short crack growth, defined as situations in which the intensity of the crack tip field is underestimated by linear elastic fracture mechanics analyses, is briefly reviewed.
Two cases are identified, cracks growing in plastically strained materials, such as occurs in high strain fatigue studies and at notch roots, and small cracks growing in single grains as occurs close to the fatigue limit in plain specimens.
Important mechanical and metallurgical features of short cracks are discussed with particular reference to the upper and lower bound definition of a short crack.
333 citations
TL;DR: In this paper, the authors extended the dislocation dipole accumulation model for fatigue crack initiation to an analysis of the fatigue strength reduction due to inclusions in high strength alloys.
Abstract: The dislocation dipole accumulation model for fatigue crack initiation previously proposed by the authors is extended to an analysis of the fatigue strength reduction due to inclusions in high strength alloys. The initiation of a fatigue crack is determined by an energy criterion under the assumption that the crack initiation takes place when the self strain energy of dislocation dipoles accumulated at the damaged part in the material reaches a critical value. Explicit formulae for the crack initiation criterion in several cases are derived as functions of the applied stress, the inclusion size, the slip band shape, and the shear moduli of the inclusion and matrix. The following three types of fatigue crack initiation at inclusions are considered: the slip-band crack emanating from a debonded inclusion, the inclusion cracking due to impinging of slip bands, and the slip-band crack emanating from an uncracked inclusion. The first mechanism was reported to be operative in high strength steels, while the last two mechanisms were reported in high strength aluminum alloys. The present theoretical results are in good agreement with the experimental data published for each case of fatigue crack initiation at inclusions.
259 citations
TL;DR: In this paper, the alloy Ti•6Al•4V has been implanted with carbon and nitrogen ions, and the microstructure produced by these implants is found to contain fine particles of TiC and TiN, respectively.
Abstract: The alloy Ti‐6Al‐4V has been implanted with carbon and nitrogen ions. The microstructure produced by these implants is found to contain fine particles of TiC and TiN, respectively. Rotating beam fatigue tests show improved fatigue life for both implants, with the superior carbon implantation giving a 20% increase in endurance limit and a factor of 4–5 lifetime increase at higher stresses over unimplanted material. A dose of 1×1017 at./cm2 is required to obtain the maximum effect. Fatigue cracks have been observed to originate up to 150 μm below the surface, indicating a complex interaction between the implanted layer and the fatigue failure process.
145 citations
TL;DR: In this paper, the low cycle fatigue and fatigue crack propagation of Inconel 718 alloy and Waspaloy were investigated at 25, 550 and 650 °C and the qualitative observations indicate that there exists a close correspondence between the near-threshold regime and stage I crack initiation in low-cycle fatigue.
124 citations
TL;DR: In this article, the authors demonstrate the effects of shallow corrosion pits up to 250μm deep on the initiation offatigue cracking in both plain and notched specimens of a low-alloy steel.
Abstract: The initiation of fatigue cracks at corrosion pits has been responsible for the failure of a wide range of engineering components The present work demonstrates the effects ofcorrosion pits up to 250μm deep on the initiation offatigue cracking in both plain and notched specimens of a low-alloy steel Fatigue strength can be reduced by as much as 70% due to the presence of such corrosion pits The concepts of linear elastic fracture mechanics are used in an attempt to describe the development and growth of fatigue cracks from shallow corrosion pits
84 citations
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01 Jan 1982
TL;DR: In this article, the authors present an analysis of the effect of different chemical and heat treatment on the physical properties of two-phase Titanium Alloys, including the effects of different types of heat treatments on the properties of each of them.
Abstract: Decomposition of the Martensite in Two-Phase Titanium Alloys- The Investigation of the Titanium Structure after Shock Wave Loading- Embrittlement and "Spontaneous" Cracking of a Hardened (?+?) Titanium Alloy during Aging- Transformation in Unstable Beta-Titanium Alloys- Internal Friction Studies in Stable and Metastable Beta Titanium Alloys- Aging Characteristics of Beta Titanium Alloys- Decomposition of the Solid Solution the The All-Beta ?III- Martensite Formation and Decomposition in Alloys of Titanium Containing ?-Stabilizing Elements- An Evaluation of Direct Aging to Achieve Optimum Mechanical Properties for the Metastable Beta Ti-8Mo-8V-2Fe-3Al Alloy- Intensification of Chemical-Thermal Treatment of Titanium and Its Alloys- Effect of Boronising on Adhesive Wear Characteristics of Titanium- Antiseizing Properties of Titanium Alloys under Different Chemical and Heat Treatment- Discussion- Critical Review Influence of Technological Factors on Structure and Properties of Titanium Alloys- Structure of Semifinished Alpha + Beta Titanium Alloy Products- Influence of the Parameters of a Laminated Structure on the Mechanical Properties of Titanium Alloys- Methods of Refining Coarse-Grained Structures of Titanium Alloys- The Influence of Polygonized Structure on the Properties of Heat-Treated Beta Titanium Alloys- Transmission Electron Microscopy Study of Structural Changes Hot Deformation of Titanium Alloys- Influence of Forging Skin on Fatigue Strength of die Forgings in Ti-6a1-4v Material- The Influence of Hydrogen on Hot Deformability of Titanium Alloys with Different Phase Compositions- The Effect of Some Technological Factors on the Structure and Properties of the Equiatomic Titanium-Nickel Alloy- Thermomechanical Properties and Stress Corrosion of RMI Ti-3A1-8V-6Cr-4Mo-4Zr- Texture Development in ?+ss Titanium Alloys- The Effect of Phase Transformation on Deformation Texture of ? and (? + ss) Titanium Alloys- The Formation of Recrystallization Texture in Ti-Al Alloys- Recrystallization of Ti-Mo Base Beta Alloys- Annealing Behavior and Strengthening of Ti-6a1-2sn- Influence of Grain Size on the Ductility of Age-Hardened Titanium Alloys- Processing and Deformation Studies on Ultrafine Grained Titanium- Effects of Texture on Deep Drawability of Commercially Pure Titanium Sheet- Influence of Processing and Heat Treatment on the Anisotropic Properties of Sheet and Strip of Commercially Pure Titanium- Mechanical Properties of Titanium Alloy Plates- Effect of Heat Treatment on the Mechanical Properties in an Alpha-Beta Titanium- The Effect of Heat Treatment on the Fatigue Strength of Ti-6A1-4V- Effect of Heat Treatment on the Microstructure and Properties of IMI 685- A Comparative Study of Creep Resistance and Thermal Stability of Alloys "685" and "6242" in Air and in Vacuum- Effects of TiA16V4 Metallurgical Structures on Fatigue Properties- The Effect of Variations in Heat Treatment on the Mechanical Properties of an ?+ss Titanium Alloy IMI 550 (Ti-4A1-2Sn-4Mo-05Si)- Heat Treatment of Cast Ti-6A1-4V Alloy- On Titanium Alloy Residual Stress Following Thermodiffusion Saturation- Discussion- Critical Review Titanium Alloys for Different Branches of Engineering- Critical Review Titanium for Engineering Purposes- Trends in the Development of High-Strength Titanium Alloys- Principles of Titanium Alloys Complex Alloying- A Titanium Alloy with Improved Mechanical Resistance Ti-6A1-6V-2Sn-6Zr- Effect of Impurities on the Working Ability of Ti-6A1-4V Type Alloy- Ti-6A1-4V for Marine Uses- Development of a New Moderate Strength, High Fracture Toughness Titanium Alloy: Ti-45A1-5Mo-L5Cr (Corona 5)- The Metallurgical Synthesis of a New Generation of Deep Hardenable Titanium Alloys The Metastable Beta Ti-Mo-V-Cr-Al System - Cracking of a Hardened (?+?) Titanium Alloy during Aging- Transformation in Unstable Beta-Titanium Alloys- Internal Friction Studies in Stable and Metastable Beta Titanium Alloys- Aging Characteristics of Beta Titanium Alloys- Decomposition of the Solid Solution the The All-Beta ?III- Martensite Formation and Decomposition in Alloys of Titanium Containing ?-Stabilizing Elements- An Evaluation of Direct Aging to Achieve Optimum Mechanical Properties for the Metastable Beta Ti-8Mo-8V-2Fe-3Al Alloy- Intensification of Chemical-Thermal Treatment of Titanium and Its Alloys- Effect of Boronising on Adhesive Wear Characteristics of Titanium- Antiseizing Properties of Titanium Alloys under Different Chemical and Heat Treatment- Discussion- Critical Review Influence of Technological Factors on Structure and Properties of Titanium Alloys- Structure of Semifinished Alpha + Beta Titanium Alloy Products- Influence of the Parameters of a Laminated Structure on the Mechanical Properties of Titanium Alloys- Methods of Refining Coarse-Grained Structures of Titanium Alloys- The Influence of Polygonized Structure on the Properties of Heat-Treated Beta Titanium Alloys- Transmission Electron Microscopy Study of Structural Changes Hot Deformation of Titanium Alloys- Influence of Forging Skin on Fatigue Strength of die Forgings in Ti-6a1-4v Material- The Influence of Hydrogen on Hot Deformability of Titanium Alloys with Different Phase Compositions- The Effect of Some Technological Factors on the Structure and Properties of the Equiatomic Titanium-Nickel Alloy- Thermomechanical Properties and Stress Corrosion of RMI Ti-3A1-8V-6Cr-4Mo-4Zr- Texture Development in ?+ss Titanium Alloys- The Effect of Phase Transformation on Deformation Texture of ? and (? + ss) Titanium Alloys- The Formation of Recrystallization Texture in Ti-Al Alloys- Recrystallization of Ti-Mo Base Beta Alloys- Annealing Behavior and Strengthening of Ti-6a1-2sn- Influence of Grain Size on the Ductility of Age-Hardened Titanium Alloys- Processing and Deformation Studies on Ultrafine Grained Titanium- Effects of Texture on Deep Drawability of Commercially Pure Titanium Sheet- Influence of Processing and Heat Treatment on the Anisotropic Properties of Sheet and Strip of Commercially Pure Titanium- Mechanical Properties of Titanium Alloy Plates- Effect of Heat Treatment on the Mechanical Properties in an Alpha-Beta Titanium- The Effect of Heat Treatment on the Fatigue Strength of Ti-6A1-4V- Effect of Heat Treatment on the Microstructure and Properties of IMI 685- A Comparative Study of Creep Resistance and Thermal Stability of Alloys "685" and "6242" in Air and in Vacuum- Effects of TiA16V4 Metallurgical Structures on Fatigue Properties- The Effect of Variations in Heat Treatment on the Mechanical Properties of an ?+ss Titanium Alloy IMI 550 (Ti-4A1-2Sn-4Mo-05Si)- Heat Treatment of Cast Ti-6A1-4V Alloy- On Titanium Alloy Residual Stress Following Thermodiffusion Saturation- Discussion- Critical Review Titanium Alloys for Different Branches of Engineering- Critical Review Titanium for Engineering Purposes- Trends in the Development of High-Strength Titanium Alloys- Principles of Titanium Alloys Complex Alloying- A Titanium Alloy with Improved Mechanical Resistance Ti-6A1-6V-2Sn-6Zr- Effect of Impurities on the Working Ability of Ti-6A1-4V Type Alloy- Ti-6A1-4V for Marine Uses- Development of a New Moderate Strength, High Fracture Toughness Titanium Alloy: Ti-45A1-5Mo-L5Cr (Corona 5)- The Metallurgical Synthesis of a New Generation of Deep Hardenable Titanium Alloys The Metastable Beta Ti-Mo-V-Cr-Al System - design and Properties- Strength and Toughness of Binary Ti-Ni and Ti-Mo Alloys- The Technological Aspects of Titanium Application in the TU-144 Aircraft Structure- Ways of Increasing Titanium Alloys High Temperature Strength- Investigation of Some Properties of VT5L Alloy with Rare Earth Additions- Characteristics of Commercially Pure Titanium for Power Plant- The Effect of Carbon on the Behavior of the Beta-Titanium Alloys- An Investigation of Some Palladium-Titanium Alloys- A Titanium Alloy for Application in Hot Sodium Chloride Solutions- On the Performance of Whole-Titanium Made Turbine Condenser- Manufacture and Properties of Titanium Tubes for Power Station Condensers- Trends in the Use of Titanium in Heat Exchange- Titanium Basket Anodes for Metal Refining and Winning- Recent Advances in Titanium Cathodes- Discussion- Critical Review Powder Metallurgy of Titanium- A Novelty in the Field of Titanium Powder Metallurgy- Production of Die-Forged Discs from BT9 Alloy Powder- Production of Titanium Parts, Apparatus and Machinery by Methods of Powder Metallurgy- Rolling of Titanium Powder and Its Alloys- The Mechanical Properties of P/M Ti-6A1-4V Alloy- Dispersion Hardening of Titanium- Production of High Purity Titanium Powder by Electron Beam Technology- Comparative Evaluation of Forged Ti-6A1-4V Bar Made from Shot Produced by Rep and CSC Processes- Critical Review Titanium Matrix Composites- Investigation of Structure of Titanium Matrix Fiber Composites- Model Composite (Layered) Material on the Basis of Titanium- The Investigation of Solid-Phase Interaction of Titanium with Refractory Compounds- The Influence of Release Agents on Properties of the Titanium Foil Produced by Vacuum Evaporation- The Application of TiC and TiN Thick Films by PVD Processes- Discussion
66 citations
TL;DR: In this article, the authors determined quantitatively the corrosion fatigue life for three different types of corrosion behavior: passive corrosion, active corrosion and pitting corrosion based on corrosion kinetics and fracture mechanics.
Abstract: Based on corrosion kinetics and fracture mechanics, it has been possible to determine quantitatively the corrosion fatigue life for three different types of corrosion behavior. Under general, active corrosion, corrosion fatigue life is controlled by the corrosion rate and the applied alternating stress range. If pitting corrosion occurs, corrosion fatigue life depends on the incubation time for nucleating a pit, the pit growth kinetics, and a critical pit depth, which is a function of the applied stress range. It has been assumed that under passive corrosion conditions, the passive layer has to be penetrated by slip steps, to form corrosion fatigue cracks. The corrosion fatigue crack initiation in this case is controlled by the repassivation kinetics of the material and also by a critical notch depth, depending on the applied stress range. It has been found that a critical current density exists, below which no corrosion fatigue cracks can initiate. Comparison of the theoretically calculated life times with experimental results showed a quite good correlation.
64 citations
TL;DR: In this paper, the case depth of a three pct Cr-Mo steel with and without the formation of a surface compound layer was investigated and the influence of this compound layer on the fatigue limit was described.
Abstract: The plasma nitriding conditions necessary to treat a three pct Cr-Mo steel with and without the formation of a surface compound layer have been investigated and the influence of this compound layer on the fatigue limit is described. The nitrided case depth has been varied as a function of time at a constant temperature of 480 °C and the corresponding rotating bending fatigue strength evaluated. This data has been used to develop a simple model to describe the influence of the case depth on the fatigue limit.
63 citations
01 Aug 1982
TL;DR: In this paper, a simple fatigue design procedure is proposed to minimize fatigue cracking in future ships, which is based on a reliability factor (factor of safety) that accounts for the many uncertainties that exist in the fatigue data, the predicted loading history and in the associated analyses, and the random nature of the loading history.
Abstract: : Fatigue cracking has for many years been responsible for extensive and costly ship repair work. This investigation provides a simple fatigue design procedure that will help to minimize such cracking in future ships. The design procedure provides for a large variety of ship details; the basic fatigue resistance of these various welded details: a reliability factor (factor of safety) that accounts for the many uncertainties that exist in the fatigue data, the predicted loading history and in the associated analyses, and the random nature of the loading history to which a ship may be subjected during its lifetime. (Author)
54 citations
TL;DR: In this paper, cold-worked Type 316 stainless steel was irradiated in the High Flux Isotope Reactor, which produces atomic displacement damage as well as helium through a two-step neutron absorption reaction with nickel.
Abstract: In a Tokamak reactor that operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially in the first wall and blanket. There has been limited work on fatigue in irradiated alloys, but none on irradiated materials containing irradiation-induced helium, which will be characteristic of fusion service. Specimens of 20% cold-worked Type 316 stainless steel were irradiated in the High Flux Isotope Reactor, which produces atomic displacement damage as well as helium through a two-step neutron absorption reaction with nickel. The specimens were irradiated at 430/sup 0/C to up to 15 dpa and 900 at. ppm helium. Following irradiation, specimens were tested in a vacuum at the irradiation temperature with total strain ranges from 0.30 to 2.0%. The irradiated specimens exhibited a reduction in fatigue life of a factor of 3 to 10 compared to unirradiated material. An endurance limit was observed at a total strain range of 0.3% for irradiated material.
45 citations
01 Jan 1982
TL;DR: In this article, a model of surface residual stresses in aluminum alloys is proposed and evaluated based on consideration of the nature of the microplastic deformation process, and it is shown that the rate of relaxation is greatest for those surface preparation processes which produce the steepest residual stress gradient normal to the surface.
Abstract: Microplastic deformation during fatigue of aluminum alloys permits relaxation of residual surface stresses at peak external stress amplitudes that are appreciably less than the yield strength. A review of the literature reveals that this process has not been adequately modeled. We propose and evaluate a model of relaxation which is based upon consideration of the nature of the microplastic deformation process. Residual surface stresses measured during fatigue of an Al 2219-T851 alloy are predicted from the cyclic stress amplitude, the initial magnitude of the residual stress and the ambient humidity during fatigue. It is shown that the rate of relaxation is greatest for those surface preparation processes which produce the steepest residual stress gradient normal to the surface. The rapid relaxation of surface residual stresses in aluminum alloys is an important effect that must be quantitatively understood before adequate prediction of the effect of such stresses on fatigue life can be made.
TL;DR: In this paper, the cyclic responses associated with plastic resolved shear strains in the range 10−6 10−2 have been investigated and the effect of crystal orientation has also been explored.
TL;DR: In this article, the effect of tensile residual stresses on the fatigue behavior of fillet welded joints under different load ratios and the relevance of the tensile strength of the steel, particularly in relation to the magnitude of residual stresses developed was investigated.
Abstract: Fatigue tests were carried out on fillet welded joints in four steels, with yield strengths ranging from 332 to 727 N/mm 2 , under various applied load ratios. Some specimens were stress-relieved but most were spot-heated to ensure that high tensile residual stresses, as would be present in as-welded joints in real structures, were present in the specimens. The aim was to investigate the effect of tensile residual stresses on the fatigue behavior of fillet welded joints under different load ratios and the relevance of the tensile strength of the steel, particularly in relation to the magnitude of residual stresses developed. In the present specimens, the residual stresses were no higher in the high-strength steels than the mild steels, with the result that the tensile strength of the steel had no effect on the fatigue strength of the joints in both the as-welded and the stress-relieved conditions. Furthermore, it was found that for the range of R-values used (R = - (zero compression to R = 0.67) applied load ratio had little effect on the fatigue strength of the as-welded joints provided that "failure" under compressive loading was taken to be a crack length less than or equal to that at which the rate of crack growth began to decrease. Stress relief was only partially effective, with the result that applied compressive stresses were still damaging. Thus under partly compressive loading the fatigue strength of the joint increased but not greatly. However, stress relief had no effect on the fatigue strength of the joint when it was subjected to tension loading.
TL;DR: In this paper, the influence of relatively high frequency low amplitude vibrations superimposed on higher amplitude low frequency major cycles for titanium alloy (Ti-6Al-4V) was studied, and it was concluded that the major cycles causing low cycle fatigue are of greatest significance during crack formation and for fatigue crack growth.
TL;DR: In this article, the room temperature static axial and axial/shear properties of thin-walled composite tubes consisting of four layers of [ ± 45]s graphite epoxy were determined using axial clips on extensometers where appropriate.
Abstract: Fixtures are described which are appropriate for static and fatigue testing of thin-walled composite tubes of 25.4 mm outer diameter and for use in an MTS servohydraulic tension-torsion system. The room temperature static ax ial and shear properties of tubes consisting of four layers of [ ± 45]s graphite epoxy were determined using axial and axial/shear clip-on extensometers where appropriate. Elastic moduli are equal in tension/compression (tor sion/reversed torsion). Ultimate tensile and compressive strengths are nearly equal. The torsional strength depends strongly on the direction of twist. Beyond the relatively small elastic range time-dependent deformation is observed which is also felt as a frequency effect on fatigue life under com pletely reversed axial load controlled loading. The room temperature axial fatigue strength amplitude at 105 cycles is approximately thirty percent of the ultimate strength.
01 Jan 1982
TL;DR: In this article, shot peening is a widely used method to improve the behavior of materials as for instance fatigue behavior or corrosion resistance The improvement of fatigue behavior is for example a consequence of either the strain hardening of surface layers or of the compressive residual stresses in surface layers induced by shot-peening or of both.
Abstract: Shot peening is a widely used method to improve the behavior of materials as for instance fatigue behavior or corrosion resistance The improvement of fatigue behavior is for example a consequence of either the strain hardening of surface layers or of the compressive residual stresses in surface layers induced by shot peening or of both It depends upon the strength or hardness of the material and upon the geometry of the workpiece which of these influencing factors is the predominant one In a high strength material, or in any notched workpiece residual stresses have an appreciable effect on the fatigue behavior and compressive residual stresses can enhance the fatigue strength (1,15,16)
TL;DR: In this article, deep rolling is applied in case of crankshafts in order to improve the fatigue properties of smooth specimens and components with a sufficient toughness by increase of surface hardness, whereas the influence of permanent compressive residual stresses is dominant.
Abstract: Die Schwingfestigkeitseigenschaften von Proben und Bauteilen konnen durch Festwalzen betrachtlich angehoben werden. Je nach Bauteilgeometrie und Werkstoffestigkeit wirken sich die durch den Festwalzprozes eingebrachten Druckeigenspannungen 1. Art und die Randhartesteigerung unterschiedlich auf die Erhohung der Dauerfestigkeit aus. Wahrend bei glatten Proben oder Bauteilen ausreichender Duktilitat der Zuwachs an Schwingfestigkeit im wesentlichen auf die Zunahme der Randharte zuruckzufuhren ist, beruht die Dauerfestigkeitserhohung von Bauteilen mit Kerben auf das Vorhandensein stabiler Druckeigenspannungen.
Die Anwendung des Festwalzprozesses bei Kurbelwellen zeigt die deutliche Uberlegenheit des mechanischen Verfestigungsverfahrens gegenuber einem rein thermischen Randschichtharteverfahren. Sollte neben der Schwingfestigkeit auch das Verschleisverhalten verbessert werden, empfiehlt sich eine Kombination von thermischem und mechanischem Oberflachenverfestigungsverfahren.
Deep Rolling and Fatigue Strength
The fatigue properties of specimens and components are largely increased by deep rolling. Depending on geometrical shape of components and material strength the compressive residual stresses and the increased surface hardness made by deep rolling have a different effect on the improvement of fatigue strength.
The fatigue properties of smooth specimens and components with a sufficient toughness can be raised by increase of surface hardness, whereas in case of notched parts the influence of permanent compressive residual stresses is dominant.
The application of deep rolling in case of crankshafts shows a clear superiority of mechanical strengthening procedure to thermal surface strengthening. If there are some reasons to improve the wear behaviour beside the fatigue strength it is commendable to combine thermal and mechanical surface strengthening.
TL;DR: In this paper, a bas carbone faiblement allies contenant Ti 0,08 a 0,26% was used for the estimation of resistance a la fatigue d'eprouvettes.
Abstract: Aciers a bas carbone faiblement allies contenant Ti 0,08 a 0,26%. Etude experimentale de la resistance a la fatigue d'eprouvettes soudees par resistance. Application de la mecanique de la rupture pour le calcul de la resistance a la fatigue en fonction de la dimension des eprouvettes
TL;DR: In this article, the tension-tension fatigue of normalized SAE 1040 steel under applied stress control, compressive residual stresses developed, but only in or near deformation markings, were eliminated during fatigue and replaced by tensile residual stresses, when the applied fatigue stress is above the endurance limit.
TL;DR: In this article, a complex function analysis for an elliptical notch under the antiplane shear is presented, which gives a quantitative method for assessment of the reduction of fatigue strength as a function of the notch tip radius, the notch size and the elastic stress concentration factor.
TL;DR: The purpose of the present work was to investigate the fatigue strength of various types of resinous materials used in dentistry and it was found that heat-cured denture base materials do not necessarily have higher fatigue strength than cold-c cured materials.
Abstract: – The fatigue properties of resinous materials may be interesting from several points of view. A good resistance to fatigue failure is desirable in a denture base material. The possible relationship between fatigue strength and wear constitutes another aspect of interest. The purpose of the present work was to investigate the fatigue strength of various types of resinous materials used in dentistry. It was found that heat-cured denture base materials do not necessarily have higher fatigue strength than cold-cured materials. At low levels of stress a tendency was demonstrated for microfilled resins to show higher fatigue strength than other types of resinous materials. On this basis a connection between wear and fatigue properties may be surmised.
TL;DR: In this article, the fatigue performance of steel-to-steel lap joints for endurances of up to 100000000 cycles was examined and work in progress to investigate effects of weathering is described.
TL;DR: In this article, the effects of metallurgical structure and graphite morphology on the fatigue behavior of cast irons are discussed and used to study the structure-property relationships in graphitic cast IRons.
TL;DR: In this article, the results of a combined experimental/analytical program on the fatigue initiation behavior of carbon steel components are described. And several improvements in the fatigue analysis procedures are suggested: (I) a notch factor for local strains, (2) a mean stress factor, (3) improved fatigue strength reduction factor for butt welds, and (4) an environmental correction factor.
Abstract: This paper describes the results of a combined experimental/analytical program on the fatigue initiation behavior of carbon steel components. Based on this study, several improvements in the fatigue analysis procedures are suggested: (I) a notch factor for local strains, (2) a mean stress factor, (3) improved fatigue strength reduction factor for butt welds, and (4) an environmental correction factor. It is shown that with the suggested fatigue analysis procedures, the fatigue design margins of the ASME Code will be maintained even with unusually severe local strain and mean stress.
TL;DR: In this article, the fatigue strength of machined specimens of ferritic SG iron has been compared with the strength of specimens having an as-cast surface, and it is demonstrated that the fatigue life of SG iron is dominated by micro-crack growth and that the effect of all types of SG -iron defects on fatigue endurance is related to defect size.
TL;DR: In this article, the authors found that joint fatigue strength could be improved significantly by eliminating the carrier in one film adhesive, and by eliminating voids (due to water vapour emitted from the composite) in another film adhesive containing no carrier but ballotini for glue-line thickness control.
TL;DR: In this paper, the effect of tempering temperature on the corrosion fatigue properties of 13 pct chromium stainless steel was studied, and three pct NaCI aqueous solution was used as the corrosive environment, and results were compared with the atmospheric fatigue properties.
Abstract: The effect of austenitizing or tempering temperature on the corrosion fatigue properties of 13 pct chromium stainless steel was studied. Three pct NaCI aqueous solution was used as the corrosive environment, and the results were compared with the atmospheric fatigue properties. Strong influence of the tempering temperature on the S-N and FCP behavior of this blading material was found. The damage ratios (corrosion fatigue limit divided by endurance limit) of these various heat treated specimens became very low by this environment. Especially, extremely low corrosion fatigue strength of the specimen tempered at 600 °C was noticed. This microstructure was strategically used to clarify the reduction of pH inside the corrosion pits which were generally formed at the fatigue crack initiation sites. FCP data in the corrosive environment showed higher resistance than the atmospheric ones at the stress intensities below 18 MPa · m1/2, and which is opposite to the generally known influence of the corrosive environments. As for the fractographic feature, an appearance of the intergranular facets was especially noticed in NaCI aqueous solution environment. The fraction of this intergranular cracking was obtained as a function of the stress intensity factor.
TL;DR: In this article, an extension of the local-strain fatigue life initiation model to accommodate residual and mean stresses is presented, which is based upon the stressstrain function of Smith, Watson and Topper and includes iterative solutions for K σ and 2N f.
Abstract: Many current fatigue design criteria for structural details present allowable stress ranges for specified design lives but neglect mean and residual stresses. The paper reviews published test results and shows that residual stresses and concomitant mean stresses can have a significant influence on fatigue resistance in certain cases. The beneficial effects of compressive residual stresses due to shot-peening are well-known. For example, shot-peening of non-load-carrying fillet-welded carbon steel and butt-welded constructional alloy steel has increased the fatigue strengths at two million cycles by 20 to 40 percent. Also, the fatigue resistance of weldments can be influenced significantly by the presence of residual stresses, provided the stress ratio is equal to or less than zero and the lives are greater than one million cycles. The fatigue strength of transverse butt welds with reinforcement intact at two million cycles has been increased by 12 percent and 24 to 33 percent for stress ratios of, respectively, 0 and - 1 through thermal stress relief. Such improvement has also been shown for longitudinal non-load-carrying fillet welds (for example, attachments, gussets, etc.) where the increases in fatigue strength at two million cycles due to thermal stress relief for stress ratios of 0, - 1, and -4 were, respectively, 15, 57, and 168 percent. The paper presents an extension of the local-strain fatigue life initiation model to accommodate residual and mean stresses. The model is based upon the stress-strain function of Smith, Watson, and Topper and includes iterative solutions for K σ and 2N f . Changes in residual stresses due to cyclic loading and fatigue lives of notches at nonzero mean stresses are predicted and compared with experimental results. Also, further extensions of the model to accommodate plane strain-that is, thickness effects-and surface roughness are discussed.
TL;DR: In this article, the authors studied the effects of frequency and hysteretic heating on the fatigue response of polypropylenes and found that at low frequency, fatigue failure appeared to be a process of crack initiation and growth with very little dissipative heating.
Abstract: Axial fatigue of two, commercial, talc-filled polypropylenes was studied. A significant result of our investigation was the identification and characterization of the failure mechanisms and the effects of frequency and hysteretic heating. Frequency was found to be important to the fatigue response of the polymers. At low frequency, fatigue failure appeared to be a process of crack initiation and growth with very little dissipative heating. At high frequency, the fatigue process was dominated by dissipative heating resulting in significant creep and modulus loss, and failure was much accelerated and due mainly to material softening and melting. Correlation of temperature rise with on-line energy loss in selected experiments enabled us to extract information from the fatigue process. The results provided some quantitative understanding of the different fatigue failure mechanisms at low and high frequencies.