• Title/Summary/Keyword: X-FEM

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Effect of Grain Size and Aging Conditions on Mechanical Properties of Al-Mg-X (X=Cr,Si) Alloy (Al-Mg-X (X=Cr, Si)합금의 기계적성질에 미치는 결정립크기와 시효조건의 영향)

  • Chang-Suk Han;Chan-Woo Lee
    • Journal of the Korean Society for Heat Treatment
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    • v.36 no.2
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    • pp.77-85
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    • 2023
  • In this study, the mechanical properties of the Al-Mg-X (X=Cr, Si) alloy, which clearly showed the influence of the specimen and grain size, were investigated by changing the specimen size extensively. In addition, the effect on the specimen size, grain size and aging condition on the mechanical properties of the grain refining alloy according to the addition of Cr was clarified, and the relationship between these factors was studied. As the specimen size decreased, the yield stress decreased and the fracture elongation increased. This change was evident in alloys with coarse grain sizes. Through FEM analysis, it was confirmed that the plastic deformation was localized in the parallel part of specimen S2. Therefore, when designing a tensile specimen of plate material, the W/L balance should be considered along with the radius of curvature of the shoulder. In the case of under-aged materials of alloys with coarse grain size, the fracture pattern changed from intergranular fracture to transgranular fracture as W/d decreased, and δ increased. This is due to the decrease in the binding force between grains due to the decrease in W. In the specimen with W/d > 40 or more, intergranular fracture occurred, and local elongation did not appear. Under-aged materials of alloys with fine grain size always had transgranular fracture over a wide range of W/d = 70~400. As W/d decreased, δ increased, but the change was not as large as that of alloys with coarse grain sizes. Compared to the under-aged material, the peak-aged material did not show significant dependence on the specimen size of σ0.2 and δ.

Combination of isogeometric analysis and extended finite element in linear crack analysis

  • Shojaee, S.;Ghelichi, M.;Izadpanah, E.
    • Structural Engineering and Mechanics
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    • v.48 no.1
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    • pp.125-150
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    • 2013
  • This paper intends to present an application of isogeometric analysis in crack problems. An isogeometric formula is developed based on NURBS basis functions - enriched and adopted via X-FEM enrichment functions. The proposed method which is represented by the combination of the two above-mentioned methods, first by using NURBS functions models the geometry exactly and then by defining level set function on domain, identifies available discontinuity in elements. Additional DOFs are allocated to elements containing the crack and X-FEM enrichment functions enrich approximate solution. Moreover, a subelement refinement technique is used to improve the accuracy of integration by the Gauss quadrature rule. Finally, several numerical examples are illustrated to demonstrate the effectiveness, robustness and accuracy of the proposed method during calculation of crack parameters.

A novel coupled finite element method for hydroelastic analysis of FG-CNTRC floating plates under moving loads

  • Nguyen, Vu X.;Lieu, Qui X.;Le, Tuan A.;Nguyen, Thao D.;Suzuki, Takayuki;Luong, Van Hai
    • Steel and Composite Structures
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    • v.42 no.2
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    • pp.243-256
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    • 2022
  • A coupled finite element method (FEM)-boundary element method (BEM) for analyzing the hydroelastic response of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) floating plates under moving loads is firstly introduced in this article. For that aim, the plate displacement field is described utilizing a generalized shear deformation theory (GSDT)-based FEM, meanwhile the linear water-wave theory (LWWT)-relied BEM is employed for the fluid hydrodynamic modeling. Both computational domains of the plate and fluid are coincidentally discretized into 4-node Hermite elements. Accordingly, the C1-continuous plate element model can be simply captured owing to the inherent feature of third-order Hermite polynomials. In addition, this model is also completely free from shear correction factors, although the shear deformation effects are still taken into account. While the fluid BEM can easily handle the free surface with a lower computational effort due to its boundary integral performance. Material properties through the plate thickness follow four specific CNT distributions. Outcomes gained by the present FEM-BEM are compared with those of previously released papers including analytical solutions and experimental data to validate its reliability. In addition, the influences of CNT volume fraction, different CNT configurations, water depth, and load speed on the hydroelastic behavior of FG-CNTRC plates are also examined.

Magnetic Field Analysis of Arc Furnace Using FEM (유한요소법을 이용한 Arc로의 자기장분포 해석연구)

  • Kim, Chan-Uk;Im, Jong-In
    • Korean Journal of Materials Research
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    • v.11 no.12
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    • pp.1091-1095
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    • 2001
  • Finite element analysis showed that strong magnetic fields were distributed around the arc furnace where the strongest magnetic field was generated around the three phase cables, and followed by the electrodes and the mast arm in decreasing order. Magnetic field decay patterns around the arc furnace could be fitted by introducing exponential formula,$Y=Y_0+Ae^{\frac-{x}{t}}$. These results showed that magnetic field intensities around the arc furnace could be estimated at any 3-dimensional positions using the finite element method (FEM).

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A study on the Injection Molding Process of the Case of Drum Type Washer using Moldflow (Moldflow를 이용한 드럼세탁기 케이스의 사출성형공정에 관한 연구)

  • Park, Chul-Woo
    • Journal of Advanced Marine Engineering and Technology
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    • v.33 no.1
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    • pp.90-96
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    • 2009
  • Injection molding process is one of the most important methods to produce plastic parts with high efficiency and low cost. Today, injection molded parts have been increased dramatically the demand for high strength and quality applications. This report investigates that the optimum injection molding condition for minimum of shrinkage. Molding shrinkage is occurred by several reasons such as thermal shrinkage, a hardening process and compressibility. This report concentrate on shrinkage by a hardening process. As Change a holding pressure and holding time, checked deflections of X, Y, Z directions by shrinkage based on same condition. In conclusion, it was found that holding pressure is stronger and holding time is longer, the deflection by shrinkage is smaller because injection molding needs enough time for cooling and high density. The FEM Simulation CAE tool. Moldflow, is used for the analysis of injection molding process.

A Study on the Bone Resorption of Artificial Hip Replacement by Two-Dimensional FEM (2차원 Side Plate FEM을 이용한 인공고관절 골흡수 연구)

  • Choi, H.Y.;Chae, S.W.;Kim, S.K.
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.12
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    • pp.75-78
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    • 1994
  • Clinically, proximal bone resorption in the femur is frequently seen postoperatively on the follow up X-rays after total hip replacement(THR). We developed the finite element model of cementless THR. The model is two dimensional side plate model, whereby the three dimensional structural integrity of the bone can be accounted for by a separate two dimensional mesh, a side plate. The subject of this article is the development and application of this two dimensional side plate FEM to study the reverse effect of the various degree of bone resorption of femur after THR. The results of this study indicates that two dimensional side plate model is good and simple alternative to complex three dimensional model and the severity of the proximal bone resorption has the effect of more increasing stress on the cortex at the level of femoral stem tip.

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Consolidation of Cu-based amorphous particles (Cu계 비정질 입자의 가압 성형)

  • Kang E. Y.;Chung Y. H.;Yoo H. G.;Park J. W.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2005.10a
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    • pp.273-276
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    • 2005
  • Packing characteristics of amorphous alloy particles were investigated by scanning electron microscopy, compositional analysis, micro-hardness test and finite element method (FEM). Electroless Ni-plating was made on the surface of the Cu-based amorphous particles before consolidation in ambient atmosphere at an intermediate region of glass transition and crystallization temperatures $(T_g\;and\;T_x)$. Some parts of the Ni-layer in the interfaces of the consolidated particles disappeared, while some of them still remained without appreciable change in compositions. No cracks or fractures were found in the particles, which may occur at low temperatures below or near $T_g$ as anticipated by the FEM analysis. Crystallization and change in hardness were not observed after consolidation.

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A Study on Chatter Stability of High Speed Spindle (고속 스핀들의 채터 안정선도)

  • Shin, Seong-beom;Lee, Hyun-Hwa;Kim, Ji-S.;Kim, Ji-Yong;Yang, Min-Yang
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.19 no.3
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    • pp.340-345
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    • 2010
  • This paper presents the chatter stability lobes of high speed spindle of five-axis machine tools. Using a FEM, we obtained the frequency response function of a spindle and the stability lobes for evaluation of chatter. In addition, this paper suggest FRF using by FEM for the prediction of chatter stable region and critical cutting depth. Therefore, critical cutting depth of is 1.3586mm and X, Y direction's chatter frequency is 901Hz and 900Hz, respectively.

Residual Stress Analysis of the Overlay Weld on the Dissimilar Metal Butt Weld (이종재이종재료 Butt 용접에 대한 Overlay 용접의 잔류응력해석)

  • Kim, Kang-Soo;Lee, Ho-Jin;Lee, Bong-Sang;Jung, In-Chul;Byeon, Jin-Gwi;Park, Kwang-Soo
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.534-537
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    • 2008
  • In recent years, the dissimilar metal, Alloy 82/182 welds used to connect stainless steel piping and low alloy steel or carbon steel components in nuclear reactor piping system have experienced cracking due to primary water stress corrosion(PWSCC). It is well known that one reason of the cracking is the residual stress by the weld. But, it is difficult to estimate exactly weld residual stress due to many parameters of welding. In this paper, the analysis of 3 FEM models made by ABAQUS Code is performed to estimate exactly the weld residual stress on the dissimilar metal weld. 3 FEM models are Butt model, Repair model and Overlay model and are the plane.strain 2D model. The thermal analysis and the stress analysis are performed on each model and the residual stresses on each model were calculated and compared respectively. Also, the specimen of Butt model was made and the residual stresses were measured by X-Ray method and Hole Drilling Technique. These results were compared with the FEM result of Butt model.

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Study of the thermal deflection error and the deflection error induced by the cutting force (절삭공구의 열변형 오차 및 절삭력 변형 오차에 관한 연구)

  • Oh, Myung-Seok;Yoon, In-Jun;Baek, Dae-Kyun
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.4
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    • pp.373-378
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    • 2002
  • This paper presents a method to predict tool deflection induced by the thermal distribution and the cutting force using FEM in milling operation. The thermal distribution of cutting tool was predicted using FEM after measuring the temperature of the end of tool and of the tool holder. The thermal deflection of cutting tool was predicted using FEM as well. The tool deflection induced by the cutting force was analyzed with the solid model of cutting tool. An end mill tool caused most of tool deflection comparing to tool holder. Most of thermal deflection came from Z-direction and most of tool deflection induced by the cutting force came from X and Y direction. Precision cutting will be accomplished when tool locations are generated considering the thermal deflection of cutting tool and the tool deflection induced by the cutting force in CAD/CAM.

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