The Experts below are selected from a list of 42012 Experts worldwide ranked by ideXlab platform
J Ringsberg - One of the best experts on this subject based on the ideXlab platform.
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life prediction of rolling contact fatigue Crack Initiation
International Journal of Fatigue, 2001Co-Authors: J RingsbergAbstract:Abstract A strategy developed for fatigue life prediction of rolling contact fatigue (RCF) Crack Initiation is presented. It combines elastic–plastic finite element (FE) analyses, multiaxial fatigue Crack Initiation models used together with the critical plane concept, fatigue damage summation calculations, and comparison of results from numerical analyses and experiments. The strategy presented is utilised and evaluated for two RCF examples: (i) a twin disc test, and (ii) a railway wheel–rail rolling contact. The results from both of the examples verify that the strategy and evaluation methodology presented can be used for fatigue life predictions of RCF Crack Initiation caused by low-cycle fatigue and ratchetting failure.
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Prediction of fatigue Crack Initiation for rolling contact fatigue
International Journal of Fatigue, 2000Co-Authors: J RingsbergAbstract:In finite element (FE) simulations of a twin disc test of a wheel/rail contact, fatigue Crack Initiation criteria for elastic shakedown, plastic shakedown and ratchetting material responses were evaluated for a pearlitic rail steel BS11 normal grade. The Chaboche material model for nonlinear isotropic and kinematic hardening was used in the FE simulations. The ratchetting material response results were compared with a constitutive ratchetting model, and there was good agreement with respect to the number of cycles to Crack Initiation and shear strain distribution below the contact surface. In addition, angles for critical planes for Crack Initiation were calculated for both plastic shakedown and ratchetting material responses. Results from simulations with the ratchetting model at constant contact pressures and varying friction coefficient showed asymptotic values of the friction coefficient at which Crack Initiation due to ratchetting will not occur.
Magd Abdel Wahab - One of the best experts on this subject based on the ideXlab platform.
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numerical analysis of the influence of micro voids on fretting fatigue Crack Initiation lifetime
Tribology International, 2019Co-Authors: Diego Infantegarcia, Magd Abdel Wahab, Eugenio Giner, H MiguelezAbstract:Abstract In this paper, the influence of the heterogeneity in the predicted Crack Initiation lifetime under fretting fatigue conditions is analysed for a regular and a random distribution of micro-voids. A critical plane analysis with two multiaxial damage criteria is performed to assess the Crack Initiation lifetime. The predicted Initiation lifetime in the heterogeneous material is compared with the results obtained in the homogeneous case. The numerical results show that the heterogeneity has a noticeable influence on the predicted Initiation lifetime. Furthermore, the numerical model suggests that a Crack may firstly initiate at the upper edge of the micro-voids located close to the contact edge, leading to a mean reduction of the predicted Crack Initiation lifetime. However, in some cases, the introduction of micro-voids reduces the stress intensity at the contact edge and thus decreasing the predicted Crack Initiation lifetime.
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fretting fatigue Crack Initiation lifetime predictor tool using damage mechanics approach
Tribology International, 2013Co-Authors: Reza Hojjatitalemi, Magd Abdel WahabAbstract:Abstract Fretting fatigue is a combination of two complex mechanical phenomena. Fretting appears between components that are subjected to small relative oscillatory motions. Once these connected components undergo cyclic fatigue load, fretting fatigue occurs. In general, fretting fatigue failure process can be divided into two main portions, namely Crack Initiation and Crack propagation. Fretting fatigue Crack Initiation characteristics are very difficult to detect because damages such as micro-Cracks are always hidden between two contact surfaces. In this paper Continuum Damage Mechanics (CDM) approach in conjunction with Finite Element Analyses (FEA) is used to find a predictor tool for fretting fatigue Crack Initiation lifetime. For this purpose an uncoupled damage evolution law is developed to model fretting fatigue Crack Initiation lifetime at various fretting condition such as contact geometry, axial stress, normal load and tangential load. The predicted results are validated with published experimental data from literature.
Ryuichiro Ebara - One of the best experts on this subject based on the ideXlab platform.
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fatigue Crack Initiation and propagation behavior of forging die steels
International Journal of Fatigue, 2010Co-Authors: Ryuichiro EbaraAbstract:Abstract In this paper, fatigue Crack Initiation and propagation behavior of forging die steels are reviewed mainly on the basis of the author’s experimental results. First of all, low cycle fatigue strength, fatigue Crack propagation behavior and thermal fatigue properties of the representative hot forging die steel SKD62 are summarized with respect to testing temperature, steel hardness, stress concentration factor of the specimen and surface treatments effect. Then, the emphasis is focused upon the recently obtained experimental results on low cycle, high cycle and giga cycle fatigue behavior of cold forging die steels. Fatigue Crack Initiation and propagation behavior of cold forging die steels is discussed with respect to steel hardness, surface roughness and stress concentration factor of specimen. Characteristics of fatigue fracture surface morphology is summarized and related to fatigue Crack Initiation and propagation mechanism of hot and cold forging die steels. Finally, recommended studies on fatigue of forging die steels are touched on briefly.
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corrosion fatigue Crack Initiation behavior of stainless steels
Procedia Engineering, 2010Co-Authors: Ryuichiro EbaraAbstract:Abstract Corrosion fatigue Crack Initiation behavior of various kinds of stainless steels is reviewed mainly on the basis of the author’s experimental results. The role of corrosion pit in the corrosion fatigue Crack Initiation process of martensitic, ferritic, austenitic, duplex and precipitation-hardening stainless steels is briefly summarized. The recent investigation of an electrochemical noise measurement method is demonstrated for 12%Cr martensitic stainless steel and 2.5%Mo containing high strength austenitic stainless steels. Finally a couple of future problems to be solved in corrosion fatigue Crack Initiation are touched on briefly.
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corrosion fatigue Crack Initiation in 12 chromium stainless steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Ryuichiro EbaraAbstract:Characteristics of corrosion fatigue failures of steam turbine blades derived from failure analysis are summarized. Then corrosion fatigue variables on corrosion fatigue strength of 12% chromium stainless steel are briefly reviewed. The paper emphasizes Initiation and growth of corrosion pits in the corrosion fatigue Crack Initiation process. A recent investigation of the early stages of corrosion pit Initiation by use of electrochemical noise measurement is demonstrated. Finally, some recommendations are given how to clarify the corrosion fatigue Crack Initiation process.
V K Jain - One of the best experts on this subject based on the ideXlab platform.
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Fretting fatigue Crack Initiation mechanism in Ti–6Al–4V
Fatigue & Fracture of Engineering Materials & Structures, 2002Co-Authors: S. A. Namjoshi, Shankar Mall, V K Jain, Ohchang JinAbstract:r Fretting fatigue Crack Initiation in titanium alloy, Ti-6Al-4V, was investigated experimentally and analytically by using finite element analysis (FEA). Various types of fretting pads were used in order to determine the effects of contact geometries. Crack Initiation location and Crack angle orientation along the contact surface were determined by using microscopy. Finite element analysis was used in order to obtain stress state for the experimental conditions used during fretting fatigue tests. These were then used in order to investigate several critical plane based multiaxial fatigue parameters. These parameters were evaluated based on their ability to predict Crack Initiation location, Crack orientation angle along the contact surface and the number of cycles to fretting fatigue Crack Initiation independent of geometry of fretting pad. These predictions were compared with their experimental counterparts in order to characterize the role of normal and shear stresses on fretting fatigue Crack Initiation. From these comparisons, fretting fatigue Crack Initiation mechanism in the tested titanium alloy appears to be governed by shear stress on the critical plane. However, normal stress on the critical plane also seems to play a role in fretting fatigue life. At present, the individual contributions/importance of shear and normal stresses in the Crack Initiation appears to be unclear; however, it is clear that any critical plane describing fretting fatigue Crack Initiation behaviour independent of geometry needs to include components of both shear and normal stresses.
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combined experimental numerical investigation of fretting fatigue Crack Initiation
International Journal of Fatigue, 2001Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:Abstract This study investigated the fretting fatigue Crack Initiation behavior of titanium alloy, Ti–6Al–4V. Tests were conducted to generate fretting fatigue failures from 2×104 to 5×107 cycles at 200 Hz. Fractography was employed to determine number of cycles to Crack Initiation, Crack location and angle of Crack orientation. Finite element analysis was conducted based on the experimental information in order to assess the ability of two critical plane approaches to predict fretting fatigue Crack Initiation behavior; the Smith–Watson–Topper critical plane parameter and the maximum shear stress range critical plane parameter. When properly formulated, these parameters predicted number of cycles to Crack Initiation and location of Crack Initiation which were in agreement with the experimental counterparts. However, these two parameters predicted different orientation angles of Crack Initiation at the contact surface. Based on the observations of orientation angles, the combined experimental–numerical approach showed that the mechanism for fretting fatigue Crack Initiation was governed by the maximum shear stress range on the critical plane.
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a shear stress based parameter for fretting fatigue Crack Initiation
Fatigue & Fracture of Engineering Materials & Structures, 2001Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:The purpose of this study was to investigate the fretting fatigue Crack Initiation behaviour of titanium alloy, Ti-6Al-4V. Fretting contact conditions were varied by using different geometries of the fretting pad. Applied forces were also varied to obtain fretting fatigue Crack Initiation lives in both the low- and high-cycle fatigue regimes. Fretting fatigue specimens were examined to determine the Crack location and the Crack angle orientation along the contact surface. Salient features of fretting fatigue experiments were modelled and analysed with finite element analysis. Computed results of the finite element analyses were used to formulate a shear stress-based parameter to predict the fretting fatigue Crack Initiation life, location and orientation. Comparison of the analytical and experimental results showed that fretting fatigue Crack Initiation was governed by the maximum shear stress, and therefore a parameter involving the maximum shear stress range on the critical plane with the correction factor for the local mean stress or stress ratio effect was found to be effective in characterizing the fretting fatigue Crack Initiation behaviour in titanium alloy, Ti-6Al-4V.
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an evaluation of parameters for predicting fretting fatigue Crack Initiation
International Journal of Fatigue, 2000Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:Abstract There are numerous fatigue parameters that can be used to determine the onset of Crack Initiation in a component subjected to constant amplitude plain fatigue. This study evaluated how well some of these parameters predict fretting fatigue Crack Initiation in titanium alloy, Ti–6Al–4V. The following Crack Initiation parameters were evaluated; the strain-life parameter, the maximum strain corrected for strain ratio effects, the maximum principal strain corrected for principal strain ratio effects, the Smith–Watson–Topper (SWT) parameter, the critical plane SWT parameter and the Fatemi and Socie (F–S) parameter. The Ruiz parameters, which are specific to fretting fatigue condition, were also evaluated. The evaluation was based on the parameter's ability to predict the number of cycles to Initiation and location for Crack Initiation. The results indicated that the maximum strain amplitude at the contact interface was an important parameter for fretting fatigue Crack Initiation. Furthermore, the results indicated that when the applied loading was corrected for the effects of contact and mean stress or strain ratio, titanium alloy, Ti–6Al–4V exposed to the fretting fatigue condition behaved in a manner similar to the plain fatigue condition.
Christopher D Lykins - One of the best experts on this subject based on the ideXlab platform.
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combined experimental numerical investigation of fretting fatigue Crack Initiation
International Journal of Fatigue, 2001Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:Abstract This study investigated the fretting fatigue Crack Initiation behavior of titanium alloy, Ti–6Al–4V. Tests were conducted to generate fretting fatigue failures from 2×104 to 5×107 cycles at 200 Hz. Fractography was employed to determine number of cycles to Crack Initiation, Crack location and angle of Crack orientation. Finite element analysis was conducted based on the experimental information in order to assess the ability of two critical plane approaches to predict fretting fatigue Crack Initiation behavior; the Smith–Watson–Topper critical plane parameter and the maximum shear stress range critical plane parameter. When properly formulated, these parameters predicted number of cycles to Crack Initiation and location of Crack Initiation which were in agreement with the experimental counterparts. However, these two parameters predicted different orientation angles of Crack Initiation at the contact surface. Based on the observations of orientation angles, the combined experimental–numerical approach showed that the mechanism for fretting fatigue Crack Initiation was governed by the maximum shear stress range on the critical plane.
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a shear stress based parameter for fretting fatigue Crack Initiation
Fatigue & Fracture of Engineering Materials & Structures, 2001Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:The purpose of this study was to investigate the fretting fatigue Crack Initiation behaviour of titanium alloy, Ti-6Al-4V. Fretting contact conditions were varied by using different geometries of the fretting pad. Applied forces were also varied to obtain fretting fatigue Crack Initiation lives in both the low- and high-cycle fatigue regimes. Fretting fatigue specimens were examined to determine the Crack location and the Crack angle orientation along the contact surface. Salient features of fretting fatigue experiments were modelled and analysed with finite element analysis. Computed results of the finite element analyses were used to formulate a shear stress-based parameter to predict the fretting fatigue Crack Initiation life, location and orientation. Comparison of the analytical and experimental results showed that fretting fatigue Crack Initiation was governed by the maximum shear stress, and therefore a parameter involving the maximum shear stress range on the critical plane with the correction factor for the local mean stress or stress ratio effect was found to be effective in characterizing the fretting fatigue Crack Initiation behaviour in titanium alloy, Ti-6Al-4V.
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an evaluation of parameters for predicting fretting fatigue Crack Initiation
International Journal of Fatigue, 2000Co-Authors: Christopher D Lykins, Sabine Mall, V K JainAbstract:Abstract There are numerous fatigue parameters that can be used to determine the onset of Crack Initiation in a component subjected to constant amplitude plain fatigue. This study evaluated how well some of these parameters predict fretting fatigue Crack Initiation in titanium alloy, Ti–6Al–4V. The following Crack Initiation parameters were evaluated; the strain-life parameter, the maximum strain corrected for strain ratio effects, the maximum principal strain corrected for principal strain ratio effects, the Smith–Watson–Topper (SWT) parameter, the critical plane SWT parameter and the Fatemi and Socie (F–S) parameter. The Ruiz parameters, which are specific to fretting fatigue condition, were also evaluated. The evaluation was based on the parameter's ability to predict the number of cycles to Initiation and location for Crack Initiation. The results indicated that the maximum strain amplitude at the contact interface was an important parameter for fretting fatigue Crack Initiation. Furthermore, the results indicated that when the applied loading was corrected for the effects of contact and mean stress or strain ratio, titanium alloy, Ti–6Al–4V exposed to the fretting fatigue condition behaved in a manner similar to the plain fatigue condition.