• 한국의류학회지
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• 제10권1호
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• pp.47-57
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• 1986

The purpose of this study is to investigate fatigue phenomema of woven fabric. In order to obtain the basic data which is available for predicting the fabric fatigue phenomena, the change of mechanical properties of woven fabrics caused by the wearing and the changes of mechanical properties of woven fabrics which were subjected to repeated tensile-shearing deformation using fabric testing machine has been investigated and compared. The fatigue of woven fabrics was examined with the value of basic mechanical properties of specimens measured by the KES-F fabric testing system and their hand value and wearing ability. The results were as follows. 1) The fatigue phenomena of woven fabrics by the wearing for 800 hours are different on the position of the body: On the portion of hip, the change of surface property was the greatest, bending hysterisis was greatly increased, thickness weight, stiffness, fullness shearing hysterisis were more increased than original fabric and T.H.V. was decreased. On the portion of knee, decreasing of tensile resilience and increasing of bending, shearing hysterisis were observed greater than any other part, and increasing of stiffness, crispness was more than original fabric. On the bottom area, the changes of mechanical property was comparatively small, H.V. and T.H.V. showed near the value of the original fabric. 2) By drycleaning most of mechanical properties showed the tendency to recover the value of the original fabric, but bending hysterisis and thickess were increased, tensile and com-pression resilience were decreased more than original fabric in all parts. 3) The fatigue phenomena caused by fabric fatigue testing machine were as follows. The decreasing of hystersis in the repeated deformation such as bending, shearing was appeared at the $10^2$ deformation, but with the increasing cycle, the tendency was slightly regained. Handle value was also appeared the lowest value at the $10^2$ deformation.

• 대한조선학회논문집
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• 제50권1호
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• pp.41-48
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• 2013

Several fatigue damages have recently been reported which cannot be resolved in the context of the existing fatigue design procedure, and they are suspected to be the cracks induced by the low cycle fatigue mechanism. To tackle the problem, a series of material tests together with fatigue tests have been carried out, and elasto-plastic notch strain analysis using nonlinear kinematic hardening model has been performed. The cyclic stress-strain curves are obtained and the nonlinear kinematic hardening model was calibrated based on the obtained material data. Also, the fatigue test with non-load-carrying cruciform fillet welded joint has been performed in low cycle fatigue regime. Then, the notch strain analyses have been carried out to find the precise elasto-plastic behavior of the material at the notch root of the cruciform joint. The variation of the material property from the base metal via HAZ up to the weld metal was taken into account using spatial variation of the material property. Then the detail elasto-plastic behavior of the welded joint subjected to the repeated cyclic loading has been investigated further through the comparison with the prediction with Neuber's rule. The calibration of the nonlinear kinematic hardening model and nonlinear notch strain analyses have been performed using the commercial FE program ABAQUS.

• 산업경영시스템학회지
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• 제6권8호
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• pp.41-48
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• 1983

On the studies of the occurrence & countermeasures of industrial fatigue, the authors obtained the following results in the prevention & recovery of the industrial fatigue. Do not overtime work. To remove the unnecessary behaviors movement. To decide the standard amounts of work. Take a rest property in the procedures of work. Adjust & Arrange the work environments. Take a sufficient mutvition calories. Have plenty in reserve worktime. Set up modernizing machinery. To pay living wages.

• 선박안전
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• 제12권
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• pp.36-43
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• 2003

Fatigue life estimation by the theoretical stress concentration factors are, in general, considerably different from test results. And in calculating stress concentration factor, it is very difficult to consider actual geometry and material property which are the notch shapes, imperfections or defects of materials such as porosities inclusions and casting defects, etc. Therefore, the paper deals with the experimental method to find out the more exact stress concentration factors by measuring the strain distributions on each specimen by 3D-ESPI(Electronic Speckle Pattern Interferometry) System. Then the fatigue lives are compared between theoretical calculations using stress concentration factors determined by 3D-ESPI system and fatigue test results

• 한국주조공학회지
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• 제39권4호
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• pp.61-74
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• 2019

The effects of Sr and (Ti-B) additives on the impact and fatigue properties of recycled (35% scrap content) AC4A aluminum alloy are investigated here. The acicular morphology of the eutectic Si phase of as-cast specimens was converted to the fibrous one with Sr additives. The grain size of the α-solid solution decreased by the addition of (Ti-B) additives. The crack initiation energy (E_i) of the impact absorption energy decreased due to the incorporation of an oxide film and inclusions depending on the scrap used. The modification of the eutectic Si morphology by Sr additives is considered as the main factor of the increase of the average impact absorption energy (E_t). The addition of (Ti-B) additives contributed to an increase in the occurrence of crack deflections due to the refining of α-Al grains, resulting in improved fatigue properties.

• Steel and Composite Structures
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• 제28권3호
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• pp.319-329
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• 2018

The field around additional cutout of the floor beam web in orthotropic bridge deck was subjected to high stress concentration, especially the weld toe between floor beam and U shaped rib and the free edge of the additional cutout. Based on different considerations, different geometrical parameters of additional cutout were proposed in European, American and Japanese specifications, and there remained remarkable differences among them. In this study, considering influence of out-of-plane deformation of floor beam web and U shaped rib, parameter analysis for additional cutout under typical load cases was performed by fine finite element method. The influence of additional cutout shape and height to the stress distribution around the additional cutout were investigated and analyzed. Meanwhile, the static and fatigue test on this structure details was carried out. The stress distribution was consistent with the finite element analysis results. The fatigue property for additional cutout height of 95mm was slightly better than that of 61.5 mm.

• Tribology and Lubricants
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• 제27권3호
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• pp.162-166
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• 2011

This study is aimed to predict the fatigue life for bearings under combined radial, thrust and moment load. In order to do this, a series of simulation such as bearing load distribution, initial surface stress, subsurface stress and fatigue analysis is needed. And using the bearing's material fatigue property we can predict fatigue life for ball bearing.

• 열처리공학회지
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• 제15권3호
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• pp.113-117
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• 2002

Fatigue characteristics of ferroelectric $Pb(Zr,Ti)O_3$ (PZT) based capacitors through donor doping is reported in this paper. La substitution up to 10% were carried out to study systematically the fatigue behaviors of epitaxial ferroelectric capacitors grown on Si using $(Ti_{0.9}Al_{0.1})N/Pt$ conducting barrier composite. Ferroelectric capacitors substituted with 10% La show sufficient low voltage switched polarization and fatigue free performance. Systematic decrease in the tetragonality of the ferroelectric phase (i.e., c/a ratio) results in the corresponding reduction in coercive voltage, sufficient remnant polarization at 1.5-3V, and good fatigue property.

• Journal of Welding and Joining
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• 제20권2호
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• pp.116-124
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• 2002

The fatigue life is predicted on tensile-shear spot weldment made from Al-Mg alloy sheet with thickness of 0.8mm using Mitchell's method and uniform material law by $B{\ddot{a}}umel$ and Seeger based on local strain approach. The fatigue properties of critical HAZ region are estimated from the tensile property using simple hardness method. To predict the fatigue life of spot weldment, the local stresses and strains at the potential critical region are estimated by Neuber's rule. The predicted fatigue life based on uniform material law using HAZ's material properties provides good results within a factor of 3, conservatively.

• Tribology and Lubricants
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• 제29권1호
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• pp.33-38
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• 2013

This study is aimed to predict the fatigue life for pitch bearings under combined radial, thrust load and moment. In order to do this, a series of simulation such as bearing load distribution, initial surface stress, subsurface stress and fatigue analysis is needd. Fatigue life for pitch bearing can be predicted by using a bearing's material fatigue property.