• 대한기계학회논문집A
• /
• 제32권7호
• /
• pp.576-582
• /
• 2008

This paper describes a synthesized photoelastic method developed for the visualization and evaluation of sound pressure distribution of elastic wave in a solid. The visualization of wave stress field is achieved by synthesizing two photoelastic pictures, in which the direction of the principal axis of linear polariscopes differs by $45^{\circ}$. From the analysis of the wave stress distribution using this method, it is possible to evaluate the characteristics of elastic waves in a solid, such as the intensity of stress, directivity and resolution characteristics of the wave emitted from a commercial probe, and characteristics of scattering from various types of defects.

• 대한기계학회논문집A
• /
• 제41권8호
• /
• pp.703-709
• /
• 2017

본 논문에서는 재분배된 크리프 응력을 근사적으로 접근하기 위해 크리프 해석에 비해 비교적 간단한 탄성 및 탄성-소성 해석법을 사용하여 그 결과와 비교하였다. 탄성해석 결과를 이용하여 $M_{\alpha}-tangent$ method의 Primary Stress와 ASME 코드의 $P_L+P_b/K_t$를 구하였고 탄성-소성 해석 결과를 이용하여 R5 코드의 ${\sigma}^R_{ref}$ 를 구하였다. 용접 형상이 있는 십자 모양의 판 형상에 굽힘 하중, 단축인장 및 이축인장이 작용하는 경우와 r/t가 5, 20인 곡관에 굽힘 하중 및 내압이 작용하는 경우 등 여러 형상에 대한 해석을 수행하였다. 요소 민감도 확인을 위해서는 판 형상에 굽힘 하중이 가해 지는 경우 여러 요소 크기에 대한 해석을 수행하였다. 간략 해석 결과는 크리프 응력과 큰 차이를 보이지 않았지만, $M_{\alpha}-tangent$ method의 경우 요소 크기에 민감하고 ASME코드와 R5코드의 결과는 요소 크기에 민감하지 않았다.

• 한국공간구조학회:학술대회논문집
• /
• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
• /
• pp.165-169
• /
• 2006

This study presents a new stress analysis method to be substituted for the elastic analysis in such a plastic design procedure. This method is accompanied by an efficient mathematical tool which can be easily handled by personal computer. The method also easily accepts arbitrary strategies by the designer for selection member size.

• 한국생산제조학회지
• /
• 제8권4호
• /
• pp.87-92
• /
• 1999

Generally the life of die is limited by fatigue fracture or dimensional inaccuracy originated from wear. In this paper to predict the fatigue life of die the stress and strain histories of die can be predicted by the analysis of elastic-plastic finite element method and the elastic analysis of die during the process analysis of workpiece. Also the stress-life curve of die material can be obtained through experiment. With the above to재 facts we propose the analysis method of prediction fatigue life in die,. In the proposed model the analysis of elastic-plastic finite element method for material is carried out by using ABAQUS. Surface force resulted from the contacting border of the die and workpiece is transformed into the nodal force of die to implement elastic analysis. besides the proposed analysis model of die is applied to extrusion die and forging. die.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 추계학술대회 논문집
• /
• pp.448-451
• /
• 2005

It was observed that after unloading or removal of the load from the specimen subjected to bending stress, partial or full elastic spring back occurred and considerable stresses have resulted while plastic deformation was considered. ABAQUS is a suite of powerful engineering simulation programs, based on the finite element method. In this paper, it was used as the main tool to analyze elastic and plastic deformations of hi-material metal joint. In the case of elastic deformations, the results were comparable to the theoretical data. Plastic deformations and residual stresses of hi-material metal joint under bending moment were obtained by ABAQUS; where the theory needs to be studied and improved further to verify the results.

• Steel and Composite Structures
• /
• 제22권6호
• /
• pp.1239-1259
• /
• 2016

The modified couple stress-based third-order shear deformation theory is presented for sigmoid functionally graded materials (S-FGM) plates. The advantage of the modified couple stress theory is the involvement of only one material length scale parameter which causes to create symmetric couple stress tensor and to use it more easily. Analytical solution for dynamic instability analysis of S-FGM plates on elastic medium is investigated. The present models contain two-constituent material variation through the plate thickness. The equations of motion are derived from Hamilton's energy principle. The governing equations are then written in the form of Mathieu-Hill equations and then Bolotin's method is employed to determine the instability regions. The boundaries of the instability regions are represented in the dynamic load and excitation frequency plane. It is assumed that the elastic medium is modeled as Pasternak elastic medium. The effects of static and dynamic load, power law index, material length scale parameter, side-to-thickness ratio, and elastic medium parameter have been discussed. The width of the instability region for an S-FGM plate decreases with the decrease of material length scale parameter. The study is relevant to the dynamic simulation of micro structures embedded in elastic medium subjected to intense compression and tension.

• 전산구조공학
• /
• 제9권1호
• /
• pp.85-91
• /
• 1996

이 논문에서는 탄성-점탄성 복합재료의 공유면에 존재하는 계면균열에 대한 해석방법을 제시하고 있다. 먼저 탄성-점탄성 대응원리를 이용하여 탄성해석식으로부터 응력확대계수에 대한 식을 유도하였다. 다음으로 시간영역 경계요소법을 이용하여 균열선단에서의 응력을 계산한 다음 응력확대계수의 값을 구하였다. 수치해석의 결과는 본 논문의 정확성과 응용가능성을 보여준다.

• Tribology and Lubricants
• /
• 제24권2호
• /
• pp.90-95
• /
• 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.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
• /
• pp.933-943
• /
• 2009

Axial loads and shaft resistances can be calculated by load transfer analysis using strain data with load level. In load transfer analysis, the elastic modulus of concrete is a one of the most important parameters to consider. The elastic modulus, $E_{50}$, suggested by ACI (American Concrete Institute), has been commonly used. However, elastic modulus of concrete shows nonlinear stress-strain characteristic, so nonlinearity should be considered in load transfer analysis. In this paper, a load transfer analysis was performed by using data obtained from bi-directional pile load tests for four cases of drilled shafts. For consideration of nonlinearity, elastic modulus was calculated by both the Fellenius method and the nonlinear method, assuming the stress-strain relation of concrete to be a quadratic function, and then, the calculated elastic modulus was applied to the estimation of shaft resistance. The calculated shaft resistances were compared with the result obtained using the constant elastic modulus of ACI code. It was found that the f-w curves are similar to each method, and elastic modulus and shaft resistances decreased as strain increased. Moreover, shaft resistances estimated from elastic modulus considering nonlinearity were 5~15% different than those obtained using the constant elastic modulus.

• 한국세라믹학회지
• /
• 제47권6호
• /
• pp.491-497
• /
• 2010

In this paper, we employed the classical molecular dynamics simulations using Tersoff's potential to calculate the elastic constants of the silicon carbide (SiC) crystal at high temperature. The elastic constants of the SiC crystal were calculated based on the stress-strain characteristics, which were drawn by the simulation using LAMMPS software. At the same time, the elastic constants of the SiC ceramics were measured at different temperatures by impulse excitation testing (IET) method. Based on the simulated stress-strain results, the SiC crystal showed the elastic deformation characteristics at the low temperature region, while a slight plastic deformation behavior was observed at high strain over $1,000^{\circ}C$ temperature. The elastic constants of the SiC crystal were changed from about 475 GPa to 425 GPa by increasing the temperature from RT to $1,250^{\circ}C$. When compared to the experimental values of the SiC ceramics, the simulation results, which are unable to obtain by experiments, are found to be very useful to predict the stress-strain behaviors and the elastic constant of the ceramics at high temperature.