• Journal of Welding and Joining
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• 제21권1호
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• pp.66-71
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• 2003

The release of residual stress by mechanical loading and unloading is often performed in the fabrication of box structure fur steel bridge. The proper degree of loading and unloading is significant at release method of residual stress by mechanical loading because that degree is changed by material and geometric shape of welded structure. Therefore, the simulation model that could exactly analyze the release of residual stress by mechanical loading is to be necessary. In this study, the non-linear behavior of weldments under external loading and unloading, such as the decrease and increase of structure stiffness, was investigated by monitoring of nominal stress and strain. Tensile loading and unloading test and the proper degree of stress relaxation was measured by sectioning technique using strain gauge. Analysis model that is indispensable for the effective application of MSR method was established on the basis of test and measurement result.

• 대한기계학회논문집A
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• 제30권8호
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• pp.873-879
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• 2006

To investigate applicability of the reference stress approach as simplified inelastic stress analysis to estimate local creep rupture, detailed finite element stress analyses of a T-piece pipe with different inner pressure and system loading levels are performed. The reference stresses are obtained from the finite element (FE) limit analysis based on elastic-perfectly-plastic materials, from which the local reference stress for creep rupture is determined from R5. The resulting inelastic stresses are compared with elastic stresses resulting from linear elastic FE calculations. Furthermore they are also compared with the stresses from full elastic-creep FE analyses. It shows that the stresses estimated from the reference stress approach compare well with those from full elastic-creep FE analysis, which are significantly lower than the elastic stress results. Considering time and efforts for full inelastic creep analysis of structures, the reference stress approach is shown to be a powerful tool for creep rupture estimates and also to reduce conservatism of elastic stress analysis significantly.

• 한국정밀공학회지
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• 제19권9호
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• pp.118-124
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• 2002

The use of ceramic inserts in hot extrusion dies offers significant technical and economic advantages over other forms of manufacture. In this paper, process simulation and stress analysis are thus combined during the design, and a data exchange program has been developed that enables optimal design of the dies taking into account the elastic deflections generated in shrink fitting the die inserts and that caused by the stresses generated in the process. The shrink fit analysis has been performed that enables optimal design of the dies taking into account the elastic deflections which generated in shrink fitting the die inserts and that caused by the stresses generated in the process and by using DEFORM software for process analysis. This data can be processed as load input data for a finite element die-stress analysis. Process simulation and stress analysis are thus combined during the die design. The stress analysis of the dies is used to determine the stress conditions on the ceramic insert by considering contact and interference effects under both mechanical and thermal loads. The results are compared with the experimental ones for verification.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.331-337
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• 2000

A numerical procedure for contact analysis and calculating subsurface stress was developed. The procedure takes the advantage of signal processing technique in frequency domain to achieve shorter computing time. Boussinesq's equation was adopted as a response function in contact analysis. The validity of this procedure was proved by comparing the numerical results with the exact solutions. The fastness of this procedure was also compared with other algorithm.

• 대한기계학회논문집A
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• 제21권10호
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• pp.1702-1711
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• 1997

A numerical study for the number of terms of a power series stress function and the effect of hybrid element size on stress analysis around a hole in loaded orthotropic composites is presented. The hybrid method coupling experimental and/or theoretical inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width glass epoxy tensile plate. The tests are done by rarying the number of terms, element size and nodal locations on the external boundary of the hybrid region. The numerical results indicate that the hybrid method is accurate and powerful in both experimental and numerical stress analysis.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2004년도 학술대회지
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• pp.339-349
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• 2004

The method for fatigue life prediction of ball bearing is proposed applying the algorithm of contact fatigue prediction based on stress analysis. In order to do this, a series of simulation such as initial surface stress analysis, EHL analysis, subsurface stress analysis and fatigue analysis are conducted from the loading at each ball location calculated for a bearing subjected to external bearing load and contact shape function. And uniaxial fatigue tests are performed to obtain fatigue parameter of AISI 52100 steel. It was found that since stress is usually higher at the inner raceway contact than at the outer raceway contact, fatigue failure occurs on the inner raceway first. When the fatigue life calculated in the stress-based method are compared with $L_{50}$ life of L-P model, Crossland criterion for the radial load increment is similar to $L_{50}$ life and Dang Van criterion for the axial load increment is similar. In the case of EHL contact. there is no difference of fatigue life between dry contact and EHL contact, when maximum Hertz pressure exceeds 2.5GPa.

• 대한기계학회논문집A
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• 제33권4호
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• pp.401-408
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• 2009

This study is performed to check the three dimensional characteristics of residual stress in the dissimilar metal weld. Although two dimensional analysis has been widely used for the assessment of weld residual stress, it has limitations to understand the stress distribution of the third direction. 3-D analysis was done to understand residual stress distribution of the welded plate. A simple butt-welded plate was considered to show the stress variation on all direction. A mock-up plate weldment was fabricated with SA-508 and F316L, which are widely used in nuclear power plants. The analysis results were validated with the measured values in the mock-up.

• 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.

• Nuclear Engineering and Technology
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• 제54권2호
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• pp.732-740
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• 2022

A piping system stress analysis need to be re-performed for structural integrity assessment after reinforcement of a pipe with significant wall thinning. For efficient stress analysis, a one-dimensional beam element for the wall-thinned pipe with reinforcement needs to be developed. To develop the beam element, this work presents analytical equations for elastic stiffness of the wall-thinned pipe with reinforcement are analytically derived for axial tension, bending and torsion. Comparison with finite element (FE) analysis results using detailed three-dimensional solid models for wall-thinned pipe with reinforcement shows good agreement. Implementation of the proposed solutions into commercial FE programs is explained.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년 영문 학술대회
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• pp.813-822
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• 2008

The present work has been developed the interpretation processor including analysis of the failure stress in pyrotechnically releasable mechanical linking device, which has the release characteristic without fragmentation and pyro-shock, using SoildWorks, COSMOS Works and ANSYS programs. The aim of the invention is to propose a pyrotechnically releasable mechanical linking device for two mechanical elements that does not suffer from such drawbacks. The pyrotechnically releasable mechanical linking device according to the invention is simple, compact and inexpensive in structure. It is simple to implement and permit the use of only a reduced quantity of pyrotechnic composition, such composition possibly being devoid of any primary explosive at all. The present work is only focused on the design of structure and the material characteristics. To analyze the fracture morphology resulted from tensile test in the different ball type bolts, the present work has been performed to estimate the failure stress of material and to make the same result from tensile test. The failure stress of SUS 630 in ductile material is approximately 1050 Mpa. The failure stress of SUS 420 in brittle material is about 1790 Mpa. Among the models used the ductile material, the model 6 is suitable a design of structure compared to that of other models. The use of this interpretation processor developed the present work could be extensively helped to estimate the failure stress of material having a complex geometry such as the ball type bolt