The Experts below are selected from a list of 177726 Experts worldwide ranked by ideXlab platform
Theodore Nicholas - One of the best experts on this subject based on the ideXlab platform.
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frequency and Stress Ratio effects in high cycle fatigue of ti 6al 4v
International Journal of Fatigue, 1999Co-Authors: R J Morrissey, David L Mcdowell, Theodore NicholasAbstract:Experiments were conducted to determine the effects of test frequency on the high cycle fatigue (HCF) behavior of Ti-6Al-4V. Specimens were tested at a range of frequencies for three different Stress Ratios (0.1, 0.5, and 0.8). Results indicate a frequency dependence that varies with Stress Ratio (R). At low R, the fatigue strength increases with increasing frequency. As R is increased, this trend continues until a transition zone is reached. Above this transition the frequency effect seems to vanish at the lower frequencies, but it is still apparent at high frequency. In addition, the material exhibits ductile behavior above the transition point. The ductile behavior is characterized by void nucleation and growth and the apparent lack of fatigue crack initiation and growth that is evident at low Stress Ratios. Scanning electron microscopy is used to examine the failure mechanisms and transition regions. Several possible explanations are presented to explain the observed frequency and Stress Ratio effects. Strain accumulation at high R is observed and is attributed to cyclic strain ratchetting.
Timo Bjork - One of the best experts on this subject based on the ideXlab platform.
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fatigue strength of tig dressed ultra high strength steel fillet weld joints at high Stress Ratio
International Journal of Fatigue, 2017Co-Authors: Tuomas Skriko, M Ghafouri, Timo BjorkAbstract:Abstract The effect of Stress Ratio on the fatigue strength of TIG-dressed fillet weld joints of S960 grade steel was studied by experimental testing, and statistical analyses using finite element (FE) modeling were performed to define geometric parameters and their effect on the Stress concentRation factor of the TIG-dressed fillet weld joints. Review of the literature and scientific publications indicated a need for studies related to both the fatigue durability of TIG-dressed ultra-high-strength steel (UHSS) weldments and the fatigue strength of these joints at high Stress Ratio. The results of the experimental fatigue tests showed that International Institute of Welding recommendations accounting for the effects of TIG-dressing on fatigue classes are too conservative for S960 grade steel, although the fatigue resistance of TIG-dressed UHSS fillet weld joints was found to decrease with increasing Stress Ratio. Statistical analysis of geometric variables and FE modeling with an idealized weld profile shape showed that toe radius and weld undercut have the greatest effect on Stress concentRation in TIG-dressed fillet weld joints. In addition, TIG-dressing was found to cause notable softening in the fusion line and heat affected zone of the TIG-dressed S960 weldments, which might have an effect on fatigue crack initiation and thus the fatigue strength of the structure.
R J Morrissey - One of the best experts on this subject based on the ideXlab platform.
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frequency and Stress Ratio effects in high cycle fatigue of ti 6al 4v
International Journal of Fatigue, 1999Co-Authors: R J Morrissey, David L Mcdowell, Theodore NicholasAbstract:Experiments were conducted to determine the effects of test frequency on the high cycle fatigue (HCF) behavior of Ti-6Al-4V. Specimens were tested at a range of frequencies for three different Stress Ratios (0.1, 0.5, and 0.8). Results indicate a frequency dependence that varies with Stress Ratio (R). At low R, the fatigue strength increases with increasing frequency. As R is increased, this trend continues until a transition zone is reached. Above this transition the frequency effect seems to vanish at the lower frequencies, but it is still apparent at high frequency. In addition, the material exhibits ductile behavior above the transition point. The ductile behavior is characterized by void nucleation and growth and the apparent lack of fatigue crack initiation and growth that is evident at low Stress Ratios. Scanning electron microscopy is used to examine the failure mechanisms and transition regions. Several possible explanations are presented to explain the observed frequency and Stress Ratio effects. Strain accumulation at high R is observed and is attributed to cyclic strain ratchetting.
Tuomas Skriko - One of the best experts on this subject based on the ideXlab platform.
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fatigue strength of tig dressed ultra high strength steel fillet weld joints at high Stress Ratio
International Journal of Fatigue, 2017Co-Authors: Tuomas Skriko, M Ghafouri, Timo BjorkAbstract:Abstract The effect of Stress Ratio on the fatigue strength of TIG-dressed fillet weld joints of S960 grade steel was studied by experimental testing, and statistical analyses using finite element (FE) modeling were performed to define geometric parameters and their effect on the Stress concentRation factor of the TIG-dressed fillet weld joints. Review of the literature and scientific publications indicated a need for studies related to both the fatigue durability of TIG-dressed ultra-high-strength steel (UHSS) weldments and the fatigue strength of these joints at high Stress Ratio. The results of the experimental fatigue tests showed that International Institute of Welding recommendations accounting for the effects of TIG-dressing on fatigue classes are too conservative for S960 grade steel, although the fatigue resistance of TIG-dressed UHSS fillet weld joints was found to decrease with increasing Stress Ratio. Statistical analysis of geometric variables and FE modeling with an idealized weld profile shape showed that toe radius and weld undercut have the greatest effect on Stress concentRation in TIG-dressed fillet weld joints. In addition, TIG-dressing was found to cause notable softening in the fusion line and heat affected zone of the TIG-dressed S960 weldments, which might have an effect on fatigue crack initiation and thus the fatigue strength of the structure.
David L Mcdowell - One of the best experts on this subject based on the ideXlab platform.
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frequency and Stress Ratio effects in high cycle fatigue of ti 6al 4v
International Journal of Fatigue, 1999Co-Authors: R J Morrissey, David L Mcdowell, Theodore NicholasAbstract:Experiments were conducted to determine the effects of test frequency on the high cycle fatigue (HCF) behavior of Ti-6Al-4V. Specimens were tested at a range of frequencies for three different Stress Ratios (0.1, 0.5, and 0.8). Results indicate a frequency dependence that varies with Stress Ratio (R). At low R, the fatigue strength increases with increasing frequency. As R is increased, this trend continues until a transition zone is reached. Above this transition the frequency effect seems to vanish at the lower frequencies, but it is still apparent at high frequency. In addition, the material exhibits ductile behavior above the transition point. The ductile behavior is characterized by void nucleation and growth and the apparent lack of fatigue crack initiation and growth that is evident at low Stress Ratios. Scanning electron microscopy is used to examine the failure mechanisms and transition regions. Several possible explanations are presented to explain the observed frequency and Stress Ratio effects. Strain accumulation at high R is observed and is attributed to cyclic strain ratchetting.
