• Steel and Composite Structures
• /
• v.50 no.3
• /
• pp.363-374
• /
• 2024

The fatigue life of steel wire is affected not only by fatigue load, but also by corrosion environment in service period. Specially, the corrosion pit will lead to stress concentration on the surface of steel wire inducing the formation of fatigue cracks, and the fatigue cracks will accelerate the corrosion process. Therefore, the corrosion fatigue of steel wire is a coupling effect. In this study, the corrosion-fatigue coupling life curve is derived with considering corrosion-fatigue pitting stage, corrosion-fatigue short crack stage and corrosion-fatigue long crack stage. In addition, the stress concentration factors of different corrosion pits are calculated by COMSOL software. Furthermore, the effect of corrosion environment factors, that is, corrosion rate, corrosion pit morphology, frequency and action factor of fatigue load, on fatigue life of steel wire is analyzed. And then, the corrosion-fatigue coupling life curve is compared with the fatigue life curve and fatigue life curve with pre-corrosion. The result showed that the anti-fatigue performance of the steel wire with considering corrosion-fatigue coupling is 68.08% and 41.79% lower than fatigue life curve and fatigue life curve with pre-corrosion. Therefore, the corrosion-fatigue coupling effect should be considered in the design of steel wire.

• Proceedings of the KSR Conference
• /
• 2007.05a
• /
• pp.340-350
• /
• 2007

The major objective of this study is to investigate the fatigue effects of rail pad on High Speed Railway with concrete slab track system. It analyzed the mechanical behaviors of HSR concrete slab track with applying rail pad stiffness based on fatigue effect(hardening and increasing stiffness) on the 3-dimensional FE analysis and laboratory test for static & dynamic characteristics. As a result, the hardening of rail pad due to fatigue loading condition are negative effect for the static & dynamic response of concrete slab track which is before act on fatigue effect. The analytical and experimental study are carried out to investigate rail pad on fatigue effected increase vertical acceleration and stress and decrease suitable deflection on slab track. And rail pad based on fatigue effect induced dynamic maximum stresses, the increase of damage of slab track is predicted by adopting fatigue effected rail pad. after due consideration The servicing HSR concrete slab track with resilient track system has need of the reasonable determination after due consideration fatigue effect of rail pad stiffness which could be reducing the effect of static and dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• Journal of Korean Academy of Nursing
• /
• v.30 no.4
• /
• pp.857-868
• /
• 2000

The purpose of the present study is to identify the mediation effect of hope between fatigue and psychosocial adjustment in women with breast cancer. The framework for this study was guided by concepts and propositions derived from the theoretical and empirical literature on fatigue, hope and adjustment. The design of this study is a descriptive correlation study using a cross-sectional design. One hundred and twenty two outpatients with early breast cancer, receiving post-surgical radiation therapy or chemotherapy, were selected from three major medical centers in Seoul, Korea. A packet including PABCF (Psychosoical Adjustment to Breast Cancer Factor), revised RPFS (Revised Piper Fatigue Scale), HHI (Herth Hope Index), and self-addressed return envelope was given to the participants at seven to eight weeks post surgery. The questionnaires were to be completed at home and returned to the researcher by mail. The obtained data were analyzed using three regression equations guided by Baron and Kenny (1986); first, hope was regressed on fatigue; second, psychosocial adjustment was regressed on fatigue; and third, psychosocial adjustment was regressed on fatigue and hope, simultaneously. In the first equation, fatigue explained 4% of the variance in hope. In the second equation, fatigue explained 47% of the variance in psychosocial adjustment. In the last equation, hope and fatigue significantly explained the variance in psychosocial adjustment. Therefore, all conditions for the test of mediation effect of hope were satisfied. For the test of the mediation effect, the beta coefficients of fatigue on psychosocial adjustment on the second and third regression equations were compared. The beta coefficients were decreased from .69 (p < .001) on the second regression equation to .63 (p < .001) on the third regression equation. Thus, the hypothesis of this study was supported. As a result of this study, the negative Influence of fatigue on psychosocial adjustment is dampened through the mediator effect of hope in women with breast cancer. Therefore, when planning care for the adverse effect of fatigue on psychosocial adjustment, oncology nurses should consider hope as a mediator between fatigue and psychosocial adjustment to breast cancer.

• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2005.11a
• /
• pp.228-229
• /
• 2005

The compressive residual stress, which is induced by shot peening process, has the effect of increasing the intrinsic fatigue strength of surface and therefore would be beneficial in reducing the probability of fatigue damage. However, it was not known that the effect of shot peening in corrosion environment. In this study, the effect of shot peening on corrosion fatigue crack growth of sping steel immersed in 6% $FeCl_3$ solution and corrosion characteristics with considering fracture mechanics. The results of the experimental study corrosion fatigue characteristics of spring steel are as follows; the fatigue crack growth rate of the shot peening material was lower than of the un peening material. And fatigue life shows more improvement in the shot peening material than un peening material. This is because the compressive residual stress of surface operate resistance of corrosion fatigue crack propagation. It is assumed that the shot peening process improve corrosive resistance and mechanical property.

• Journal of the korean Society of Automotive Engineers
• /
• v.11 no.1
• /
• pp.51-56
• /
• 1989

This study was performed to investigate the effect of defect on fatigue strength under the stress of rotary bending. The specimens were made of low carbon steel having artificial microholes, namely, single micro-hole and two adjacent micro-holes as natural defects, and the effects of the diameter of hole and the distance between the holes on fatigue strength have been investigated. The obtained result can be summarized as follows: 1, The critical defect means the largest size of defect that does not affect fatigue limit, and correspondes to the size of defect leading to final fracture under fatigue limit of smooth specimen. The size of defect which has an effect on fatigue limit is larger than that of critical defect. 2, The defect larger than the critical defect affects fatigue strength for as a kind of size effect, and the physical meaning of size effect of defect is considered same as the one of notch effect.

• Journal of Ocean Engineering and Technology
• /
• v.13 no.2 s.32
• /
• pp.58-65
• /
• 1999

The effect of specimen thickness on fatigue crack growth rate was studied. The objective of the present study is to investigate the effect of specimen thickness on the fatigue crack growth behavior at various stress intensity factor ranges and also the variation of material restance to fatigue crack growth. The fatigue crack growth resistance was treated as a spatial stochastic process, which varies randomly on the crack path, Compact tension specimens with a LT orientation for structural steel were used. All testing was done at a constant stress intensity level. The experimental data were analyzed for the size effect to determine the Weibull distributions of the material resistance.

• Asian Oncology Nursing
• /
• v.12 no.4
• /
• pp.274-279
• /
• 2012

Purpose: This study was conducted to test whether sleep disturbance mediates the effect of pain on fatigue, whether fatigue mediates the effect of pain on depression, and whether fatigue mediates the effect of sleep disturbance on depression. Methods: This study was conducted from September 12th to December 20th, 2011. One hundred eighty-eight breast cancer patients were recruited from D city and S city in Korea. The instruments used in this study were the pain, sleep disturbance, fatigue, and depression scales. Data were analyzed using descriptive statistics, Pearson correlation coefficients, and mediation pathway with the SPSS 12.0 and AMOS 20.0 programs. Results: There was correlation among pain, fatigue, sleep disturbance, and depression. Mediation analyses indicated that pain influences fatigue. sleep disturbance, and depression directly as well as indirectly. Sleep disturbance influences fatigue and depression directly, also fatigue influences depression directly. But sleep disturbance had no direct effect on depression. Conclusion: Significant correlations among the four symptoms supported the existence of the symptom cluster. Effects of pain on fatigue was partially mediated by sleep disturbance, also effects of pain on depression was partially mediated by fatigue. However, the effects of sleep disturbance on depression was fully mediated by fatigue.

• Journal of the Korean Society for Railway
• /
• v.10 no.5
• /
• pp.499-505
• /
• 2007

The major effective of this study is to investigate the fatigue effects of rail pad on High Speed Railway with concrete slab track system. It analyzed the mechanical behaviors of HSR concrete slab track with applying rail pad stiffness based on fatigue effect (hardening and increasing stiffness) on the 3-dimensional FE analysis and laboratory test for static & dynamic characteristics. As a result, the hardening of rail pad due to fatigue loading condition are negative effect for the static & dynamic response of concrete stab track which is before act on fatigue effect. The analytical and experimental study are carried out to investigate rail pad on fatigue effected increase vertical acceleration and stress and decrease suitable deflection on slab track. And rail pad based on fatigue effect induced dynamic maximum stresses, the increase of damage of slab track is predicted by adopting fatigue effected rail pad. after due consideration. The servicing HSR concrete slab track with resilient track system has need of the reasonable determination after due consideration fatigue effect of rail pad stiffness which could be reducing the effect of static and dynamic behavior that degradation phenomenon of structure by an unusual response characteristic and a drop durability.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.14 no.3
• /
• pp.88-94
• /
• 2006

The compressive residual stress, which is induced by shot peening process, has the effect of increasing the intrinsic fatigue strength of surface and therefore would be beneficial in reducing the probability of fatigue damage. However, the effect of shot peening in corrosion environment was not known. In this study, investigated is the effect of shot peening on corrosion fatigue crack growth of SAE 5155 steel immersed in 6% $FeCl_3$ solution and corrosion characteristics with considering fracture mechanics. The results of the experimental study corrosion fatigue characteristics of SAE 5155 are as follows; the fatigue crack growth rate of the shot peening material was lower than that of the non-peening material. And fatigue life shows more improvement in the shot peening material than in non-peening material. This is due to the compressive residual stress of surface increases resistance of corrosion fatigue crack propagation. It is assumed that the shot peening process improve corrosive resistance and mechanical property.

• Tribology and Lubricants
• /
• v.31 no.6
• /
• pp.272-280
• /
• 2015

Recently, Luu suggested fatigue life equation that uses every term of the Crossland equation with stress gradient effect. Luu’s model, however, has a limit of being unable to coverage small radii that are less than a specified length. Furthermore, rolling model has a very small contact area compared to the rolling element size, and fatigue failure occurs on the small radius such as surface asperity by cyclic loading. Therefore, it is necessary to modify fatigue life equation in order to enable fatigue analysis for a small radius. In this paper, the fatigue life considering a stress gradient effect in rolling contact was obtained using Luu’s modified equation. Fatigue analysis was performed to study the effect of stress gradient on the fatigue life using newly adopted equation and to compare the results with pervious models. In order to do this, a series of simulation such as surface stress analysis, subsurface stress analysis, and fatigue analysis are conducted for two rolling balls of same size that contact each other. Through such a series of processes, the fatigue life can be calculated and equation that is proposed in this paper evaluates the fatigue life in case the contact area is small.