• Proceedings of the KSME Conference
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• 2004.11a
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• pp.425-429
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• 2004

In real design of the high & interim pressure turbine casing, it is one of the important things to figure out its thermal strain exactly. In this paper, with the establishment of the new concept for the heat transfer coefficient of steam that is one of the factors in analysis of the thermal stress for turbine casing, an analysis was done for one of the high & interim pressure turbine casings in operating domestically. The sensitivity analysis of the heat transfer coefficient of steam to the thermal strain of the turbine casing was done with a 2-D simple model. The analysis was also done with switching of the material properties of the turbine casing and resulted in that the thermal strain of the turbine casing was not so sensitive to the heat transfer coefficient of steam. On the basis of this, 3-D analysis of the thermal strain for the high and interim pressure turbine casing was done.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.669-685
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• 2015

A three-dimensional elastoplastic constitutive model, also known as a UH model (Yao et al. 2009), was developed to describe the stress-strain relationship for normally consolidated and over-consolidated soils. In this paper, an acoustic tensor and discriminator of bifurcation for the UH model are derived for the strain localization of saturated clays under undrained and fully and partially drained conditions. Analytical analysis is performed to illustrate the points of bifurcation for the UH model with different three-dimensional stress paths. Numerical analyses of cubic specimens for the bifurcation of saturated clays under undrained and fully and partially drained conditions are conducted using ABAQUS with the UH model. Analytical and numerical analyses show the similar bifurcation behaviour of overconsolidated clays in three-dimensional stress states and various drainage conditions. The results of analytical and numerical analyses show that (1) the occurrence of bifurcation is dependent on the stress path and drainage condition; and (2) bifurcation can appear in either a strain-hardening or strain-softening regime.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2435-2440
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• 2012

In this paper, Solidworks was used to do a conceptional design of an box of an electric saver in order to manufacture an electric saver having a different performance and model. Based on this, analysis was made considering weight concentrated on an box. 3-dimensional finite element analysis code, ANSYS was applied to obtain stress, strain and deformation in order to secure durability and these data was reflected to a detailed drawing.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.561-564
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• 2004

Steel sheet pile can be alternative material for bridge abutment for. The steel sheet pile bridge abutment is new and replacement bridge abutment due to its aesthetically attractive and cost effective. Use of embedded steel sheet piling brings savings in dead load, provides a compliant retaining wall, and permits speedier construction. In addition, for replacement bridge projects, traffic interruption can be minimized. It is hoped that this study will encourage designers and constructors to consider a steel substructure option more frequently during the conceptual and preliminary design phases of projects and thereby to take advantage of the potential to construction more efficiently. In this paper, an analysis of stress and strain for steel sheet pile bridge abutment was conducted. From the analysis results, the stress and strain characteristics of steel sheet pile bridge abutment with variations of steel sheet pile parameters is suggested.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.378-383
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• 2008

Bogie frame of the locomotive is an important structural member for the support of vehicle loading. A lot of study has been carried out for the prediction of the structural integrity of the bogie frame in experimental and theoretical domains. The objective of this paper is to estimate the structural integrity of the bogie frame. Strength analysis has been performed by finite element analysis. From these analysis, stress concentration areas were investigated. For evaluation of the loading conditions, dynamic stress were measured by using strain gage. It has been found that the stress and strain due to the applied loads were multi-axial condition according to the location of strain gage. The fatigue strength evaluations of the bogie frame are performed to investigate the effect of the multi-axial load through the employment of the critical plane approach.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.145-150
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• 2002

It has been well known that ductile fracture of steels is accelerated by triaxial stresses. The characteristics of ductile crack initiation in steels are evaluated quantitatively using two-parameters criterion based on equivalent plastic strain and stress triaxiality. It has been demonstrated by authors using round-bar specimens with circumferential notch in single tension that the critical strain to initiate ductile crack from specimen center depends considerably on stress triaxiality, but surface cracking of notch root is in accordance with constant strain condition. In order to evaluate the stress/strain state in the specimens, especially under dynamic loading, a thermal, elastic-plastic, dynamic finite element (FE) analysis considering the temperature rise due to plastic deformation has been carried out. This study provides the fundamental clarification of the effect of strength mismatching, which can elevate plastic constraint due to heterogeneous plastic straining, loading mode and loading rate on critical condition to initiate ductile crack from notch root using equivalent plastic strain and stress triaxiality based on the two-parameter criterion obtained on homogeneous specimens under static tension. The critical condition to initiate ductile crack from notch root for strength mismatched bend specimens under both static and dynamic loading would be almost the same as that for homogeneous tensile specimens with circumferential sharp notch under static loading.

• Journal of Welding and Joining
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• v.8 no.3
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• pp.79-88
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• 1990

Welded joint often contains soft or softened regions such as the HAZ of TMCP steel welded with high heat input. In this study, the equivalent yield strength of plate structure containing softened region was predicted by FEM analysis, and its incremental behavior was explained with the results of the analysis. The calculated results of yield strength indicated the following for the plate structures. 1) As the softened region starts to yield, shear stress begins to build up along the boundary between base metal and softened region. This results in multi-axial stress condition which gives restraint on the softened region. 2) Restraint effect has a significant influence on the distribution of the shear stress, the nominal stress, and the strain. 3) The yielding behavior of softened region becomes the same as that of base metal when both ratios of length to width and thickness to width of softened region are larger than 30 and 13 respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.3
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• pp.265-270
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• 2006

When the dynamic crack propagates along the boundary at the strip with composite materials and tears apart it, the equivalent stress and strain, and the traction stress are investigated near its boundary. There are the maximum equivalent stress and plastic strain at the very seperated part and the maximum displacement at the bent part of the end of strip. The traction stress becomes higher as the separation distance becomes more. Its maximum value becomes 75 MPa as this distance becomes 0.015 mm. As this distance becomes more than 0.015 mm, this stress becomes lower. As this distance becomes more than 0.13 mm, the value of this stress becomes 0 constantly. This study aims at doing the basic study to provide the data necessary for the precise analysis of fracture intensity, the safety design and the development of advanced materials.

• Journal of Welding and Joining
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• v.21 no.3
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• pp.68-77
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• 2003

It is important to understand the characteristics of material strength and fracture under the dynamic loading like as earthquakes to assure the integrity of welded structures. The characteristics of dynamic strength and fracture in structural steels and their welded joints should be evaluated based on the effects of the strain rate and the service temperature. It is difficult to predict or measure temperature rise history with the corresponding stress-strain behavior. In particular, material behaviors beyond the uniform elongation can not be precisely evaluated, though the behavior at large strain region after the maximum loading point is much important for the evaluation of fracture. In this paper, the coupling phenomena of temperature and stress-strain fields under the dynamic loading was simulated by using the finite element method. The modified rate-temperature parameter was defined by accounting for the effect of temperature rise under the dynamic deformation, and it was applied to the fully-coupled analysis between heat conduction and thermal elastic-plastic behavior. Temperature rise and stress-strain behavior including complicated phenomena were studies after the maximum loading point in structural steels and their undermatched joints and compared with the measured values.

• Tribology and Lubricants
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• v.24 no.2
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• pp.90-95
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• 2008

An elastic-plastic contact analysis is developed using a semi-analytical method. The elastic contact is solved within a Hertz theorem. The reciprocal theorem with initial strains is then introduced, to express the surface geometry as a function of contact stress and plastic strains. The irreversible nature of plasticity leads to an incremental formulation of the elastic-plastic contact problem, and an algorithm to solve this problem is set up. Closed form expression, which give residual stresses and surface displacements from plastic strains, are obtained by integration of the reciprocal theorem. The distribution of contact stress, residual stress and plastic strain are obtained by the changed surface geometry.