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Fatigue Data (fatigue + data)
Selected AbstractsEffect of hardness on multiaxial fatigue behaviour and some simple approximations for steelsFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 8 2009N. SHAMSAEI ABSTRACT Constant-amplitude in-phase and 90° out-of-phase axial-torsional fatigue tests were conducted on tubular specimens made from a medium-carbon steel with three hardness levels obtained from normalizing, quenching and tempering and induction hardening to find the effect of hardness on multiaxial fatigue behaviour. In addition, the same loadings were applied on the normalized solid specimens to investigate the effect of specimen geometry on multiaxial fatigue life. Similar fatigue life variation as a function of hardness was found for in-phase and out-of-phase loadings, with higher ductility beneficial in low-cycle fatigue (LCF) and higher strength beneficial in high-cycle fatigue (HCF). Multiaxial fatigue data were satisfactorily correlated for all hardness levels with the Fatemi,Socie parameter. Furthermore, in order to predict multiaxial fatigue life of steels in the absence of any fatigue data, the Roessle,Fatemi hardness method was used. Multiaxial fatigue lives were predicted fairly accurately using the Fatemi,Socie multiaxial model based on only the hardness level of the material. The applicability of the prediction method based on hardness was also examined for Inconel 718 and a stainless steel under a wide range of loading conditions. The great majority of the observed fatigue lives were found to be in good agreement with predicted lives. [source] Improvement in the fatigue strength of chromium electroplated AISI 4340 steel by shot peeningFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 2 2009H. J. C. VOORWALD ABSTRACT In landing gear, an important mechanical component for high responsible applications, wear and corrosion control is currently accomplished by chrome plating or hard anodising. However, some problems are associated with these operations. Experimental results have also shown that chrome-plated specimens have fatigue strength lower than those of uncoated parts, attributed to high residual tensile stress and microcracks density contained into the coating. Under fatigue conditions these microcracks propagate and will cross the interface coating-substrate and penetrate base metal without impediment. Shot peening is a surface process used to improve fatigue strength of metal components due to compressive residual stresses induced in the surface layers of the material, making the nucleation and propagation of fatigue cracks difficult. This investigation is concerned with analysis of the shot peening influence on the rotating bending fatigue strength of hard chromium electroplated AISI 4340 steel. Specimens were submitted to shot peening treatment with steel and ceramic shots and, in both cases, experimental results show increase in the fatigue life of AISI 4340 steel hard chromium electroplated, up to level of base metal without chromium. Peening using ceramic shot resulted in lower scatter in rotating bending fatigue data than steel shots. [source] Modelling curved S,N curvesFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 5 2005S. LORÉN ABSTRACT The fatigue limit distribution is estimated using fatigue data and under the assumption that the fatigue limit is random. The stress levels for the broken and unbroken specimens are used. For the broken specimen the number of cycles to failure is also used. By combining the finite life and fatigue limit distribution it is possible to get the probability of not surviving a certain life. This probability is used to estimate a curved S,N curve by using the method of likelihood. The whole S,N curve is estimated at the same time. These curves show the predictive life given a certain stress level. The life and the quantile of the fatigue limit distribution are also predicted by using profile predictive likelihood. In this way the scatter around the S,N curve as well as the uncertainty of the S,N curve are taken into account. [source] Interaction equations for multiaxial fatigue assessment of welded structuresFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2004M. BÄCKSTRÖM ABSTRACT Multiaxial fatigue data from 233 welded test specimens taken from eight different studies have been evaluated based on three published interaction equations for normal and shear stress. The interaction equations were obtained from SFS 2378, Eurocode 3 and International Institute of Welding (IIW) recommendations. Fatigue classes for normal and shear stress were obtained directly from the design guidance documents. Additionally, mean fatigue strengths were determined by regression analysis of bending only and torsion only data for different specimen types. In some cases, the S,N slopes assumed by the different standards were not appropriate for the test data. Specimens that showed significantly different cracking locations or cracking mode between bending and torsion were not easily correlated by the interaction equations. Interaction equations work best in cases where both the normal stress and the shear stress tend to produce crack initiation and growth in the same location and in the same direction. The use of a damage summation of 0.5 for non-proportional loading as recommended by IIW was consistent with experimental observations for tube-to-plate specimens. Other codes used a damage sum of unity. [source] Fatigue life prediction and failure analysis of a gas turbine disc using the finite-element methodFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 9 2004R. A. CLÁUDIO ABSTRACT A numerical prediction of the life of a gas turbine model disc by means of the finite-element technique is presented and the solution is compared with an experimental rim-spinning test. The finite-element method was used to obtain the K solution for a disc with two types of cracks, both at the notch root of the blade insert and located in the corner and in the centre. A crack aspect ratio of (a/c) = 1 was assumed. The fracture mechanics parameters J -integral and K were used in the assessment, which were computed with linear elastic and elastic,plastic material behaviour. Using a crack propagation program with appropriate fatigue-creep crack growth-rate data, previously obtained in specimens for the nickel-based superalloy IN718 at 600 °C, fatigue life predictions were made. The predicted life results were checked against experimental data obtained in real model discs. The numerical method, based on experimental fatigue data obtained in small laboratory specimens, shows great potential for development, and may be able to reduce the enormous costs involved in the testing of model and full-size components. [source] Low-cycle fatigue of 1Cr,18Ni,9Ti stainless steel and related weld metal under axial, torsional and 90° out-of-phase loadingFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 6 2004X. CHEN ABSTRACT The fatigue behaviour of base metal and weld joints of 1Cr,18Ni,9Ti stainless steel has been studied under uniaxial, torsional and 90° out-of-phase loading. A significant degree of additional hardening is found for both base metal and weld metal under 90° out-of-phase loading. Both base metal and weld metal have the same cyclic stable stress,strain relationship under torsional cyclic loading and 90° out-of-phase cyclic loading. Base metal exhibits higher cyclic stress than weld metal under uniaxial loading, and Young's modulus and yield stress of weld metal are smaller than those of base metal. Weld metal exhibited lower fatigue resistance than base metal under uniaxial and torsional loading, but no significant difference was found between the two materials under 90° out-of-phase loading. A large scatter of fatigue life is observed for weld metal, perhaps because of heterogeneity of the microstructure. The Wang,Brown (WB) damage parameter and the Fatemi,Socie (FS) damage parameter, both based on the shear critical plane approach, were evaluated relative to the fatigue data obtained. [source] Mechanical and corrosion properties of spot-welded high-strength austenitic stainless steel EN 1.4318MATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 4 2008M. T. Alenius Abstract Mechanical and corrosion properties of spot-welded high-strength austenitic stainless steels EN 1.4318 2H/C1150 and EN 1.4318 2H/C850 were studied. Microhardness measurements, lap shear and cross-tension tests, corrosion fatigue tests and corrosion tests were carried out. The corrosion environment was 3.5% sodium chloride solution at +50,°C in the corrosion fatigue tests and 3.5% sodium chloride solution at ambient temperature in the electrochemical pitting corrosion tests. Stainless steel EN 1.4318 2H/C850, t,=,1.92 mm, exhibited better fatigue endurance than EN 1.4318 2H/C1150, t,=,1.2 mm, and EN 1.4318 2H/C850, t,=,1.0 mm, stainless steels did. There were no significant differences between the stainless steels of different strength levels (2H/C850 vs. 2H/C1150) in the line load range analysis of the fatigue data. High hardness gradient was found in the heat-affected zone (HAZ) of EN 1.4318 2H/C1150 stainless steels. EN 1.4318 2H/C1150, t,=,1.2 mm, stainless steels seemed to have slightly higher lap shear strength with the same nugget diameter as EN 1.4318 2H/850, t,=,1.9 mm, stainless steel. In the case of EN 1.4318 2H/C1150 stainless steel increase in the nugget diameter bigger than required 5,t did not increase the cross-tension force significantly. The pitting corrosion susceptibility of the spot-welded samples and the base materials of the steels EN 1.4318 2H/C850 and EN 1.4318 2H/C1150, t,=,1.2 mm, was investigated by measuring the corrosion current for 1 h at +100 mV versus saturated calomel electrode (SCE) in 3.5% sodium chloride solution at ambient temperature. Pitting corrosion occurred in all spot-welded samples but not in the base materials. There was a difference between the investigated steels in the location of the pits. In stainless steels EN 1.4318 2H/C850 the pits appeared around the spot weld, but in the steel EN 1.4318 2H/C1150, t,=,1.2 mm, the pits are located mainly at the spot-weld area. [source] Applicability of published data for fatigue-limited designQUALITY AND RELIABILITY ENGINEERING INTERNATIONAL, Issue 8 2009Martin Leary Abstract The use of published fatigue data provides an expedient basis for fatigue-limited engineering design by alleviating the necessity of explicit testing. However, published fatigue data often exhibits incomplete documentation of the associated test conditions. Incomplete documentation introduces uncertainties in fatigue life prediction that may limit the applicability of the published fatigue data for design applications. Characterization of the applicability of published fatigue data is critical for robust fatigue-limited design. However, no quantitative methods have been identified which respond to this requirement. A novel method has been developed to provide a systematic characterization of the applicability of published fatigue data based on internationally recognized standards. This method provides a conceptual mechanism to: identify the applicability of published fatigue test data for specific design scenarios,thereby informing engineers of potential limitations of published data and allowing prioritization of multiple data sources; identify material domains of insufficient applicability,thereby providing a robust basis for identifying beneficial fatigue test programs; compromise between design complexity and the uncertainties inherent in fatigue life prediction; define a framework for the appropriate documentation of published fatigue data. A sample of published fatigue data sources associated with a specific fatigue-limited safety,critical design scenario was assessed by the method presented in this paper. For the majority of the sampled references, the associated documentation was insufficient to allow the fatigue test data to be confidently applied to the subsequent design activity. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||