• Title/Summary/Keyword: Residual Deformation

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Effects of Sand Blasting on TiAlN Coating on WC Hard Metal Alloy Tip (WC위 TiAlN 코팅층에 미치는 Sand Blasting 처리의 영향)

  • Lee, Han-Young
    • Tribology and Lubricants
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    • v.37 no.2
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    • pp.54-61
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    • 2021
  • The effect of the sand blasting before TiAlN coating in the manufacture of WC hard metal alloy tips have been studied. For four different tips, according to the status of processing of the sand blasting and the coating, residual stress measurement by X-ray diffraction and several tests for mechanical properties have been conducted. The results suggest that there was no difference in static mechanical properties, such as hardness, surface roughness and elastic modulus, between two coatings. Furthermore, compressive residual stress was generated equally on their surfaces. Additionally, the compressive residual stress in substrate WC was found to increase greatly when subjected to sand blasting treatment. However, the compressive residual stress decrease after coating regardless of sand blasting treatment. Nevertheless, it is confirmed that the compressive residual stress generated in the coating after sand blasting is less than that in the non-sandblasting coating. This was attributed to the plastic deformation occurring in the WC substrate during coating after sand blasting. In contrast to the scratch test results, sand blasting was assumed to have a negative effect on the adhesion between the coating and substrate. This is because there is a high possibility of microcracks due to plastic deformation in the WC substrate under the coating after sand blasting.

Deformation Analysis of Injection Molded Articles due to In-mold Residual Stress and Subsequent Cooling after Ejection (사출 성형품의 금형내 잔류음력과 이형후 냉각에 의한 후변형 해석)

  • Yang, Sang-Sik;Gwon, Tae-Heon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.26 no.2
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    • pp.340-348
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    • 2002
  • Deformation analysis of injection molded articles whose geometry is considered as the assembly of thin flat plates has been conducted. For the in-mold analysis, thermo-viscoelastic stress calculation of thermo-rheologically simple amorphous polymer and in-mold deformation calculation considering the in-plane mold constraint have been done. Free volume theory has been used to represent the non-equilibrium density state during the fast cooling. At ejection, instantaneous deformation takes place due to the redistribution of in-mold residual stress. During out-of-mold cooling after ejection, thermoelastic model based on the effective temperature has been adopted for the calculation of out-of-mold deformation. In this study, emphasis is also made on the treatment with regard to lateral constraint types during molding process. Two typical mold geometries are used to test the numerical simulation modeling developed in this study.

Residual Deformation Analysis of Composite by 3-D Viscoelastic Model Considering Mold Effect (3-D 점탄성 모델을 이용한 복합재 성형후 잔류변형해석 및 몰드 효과 연구)

  • Lee, Hong-Jun;Kim, Wie-Dae
    • Composites Research
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    • v.34 no.6
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    • pp.426-433
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    • 2021
  • The carbon fiber reinforced plastic manufacturing process has a problem in that a dimensional error occurs due to thermal deformation such as residual stress, spring-in, and warpage. The main causes of thermal deformation are various, including the shape of the product, the chemical shrinkage, thermal expansion of the resin, and the mold effect according to the material and surface condition of the mold. In this study, a viscoelastic model was applied to the plate model to predict the thermal deformation. The effects of chemical shrinkage and thermal expansion of the resin, which are the main causes of thermal deformation, were analyzed, and the analysis technique of the 3-D viscoelastic model with and without mold was also studied. Then, the L-shaped mold effect was analyzed using the verified 3D viscoelastic model analysis technique. The results show that different residual deformation occurs depending on the surface condition even when the same mold is used.

Time-dependent Deformation Charateristics of Geogrid Using Wide Width Tensile Test (광폭인장시험을 통한 지오그리드의 시간의존적 변형 거동 고찰)

  • Yoo, Chung-Sik;Jeon, Han-Yong;Kim, Sun-Bin
    • Journal of the Korean Geotechnical Society
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    • v.24 no.1
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    • pp.71-80
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    • 2008
  • This paper presents the reusults of wide width tensile tests under sustained and cyclic loads with vairous loading rate on geogrids. A seires of modified wide width tensile tests were conducted to investigate the effect of tensile strain rate on the deformation behavior of the geogrids. In addition, residual deformation characteristics of a geogrid under sustained or cyclic tests were also investigated. The results indicated that the residual deformation of a geogrid is strongly related to the viscous behavior of the geogrid, and the residual deformation can be well described by a hyperbolic curve. Also revealed was that residual deformation of a geogrid when subject to sustained or cyclic load should be described with the framework of viscous behavior.

Deformation and Residual Stress of Automotive Frame by Welding (용접에 의한 자동차용 Frame의 변형과 잔류 응력 분석)

  • Park, Tae-Won;Kim, Kee-Joo;Han, Chang-Pyung;Lee, Young-Suk;Lim, Jong-Han
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.5
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    • pp.113-117
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    • 2011
  • The frame for automotive assembly can be deformed and remained on the residual stress due to high temperature thermal attacks when in welding. The frame deformation can be made to problems when in assembly with body and the residual stress can affect the negative effect on durability performance of the automobile. In order to analyze the frame deformation, the simplified test frame which had the similar shape (form) of the real automotive frame was fabricated. The contactless optical 3D scanner was used for the shape difference measurement of the frame between before and after the welding. The FE-model of the test frame was composed and the heat transfer and thermal stress simulation were performed. The simulated results were compared with the measured results for the reference of the frame design. The deformation shape of the frame by simulation was in good agreement with that by the experimental measurement.

Pilot study for investigating the inelastic response of a new axial smart damper combined with friction devices

  • Mirzai, Nadia M.;Hu, Jong Wan
    • Steel and Composite Structures
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    • v.32 no.3
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    • pp.373-388
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    • 2019
  • This study proposes a new concept of an axial damper using the combination of shape memory alloy (SMA), friction devices, and polyurethane springs. Although there are many kinds of dampers to limit the damages, large residual deformation may happen and it causes much repairing cost for restoring the structure to the initial position. Also in some of the dampers, a special technology for assembling and fabricating is needed. One of the most important advantages of this damper is the ability to remove all the residual deformation using SMA plates and simple assembling without any special technology to fabricate. In this paper, four different dampers (in presence or omission of friction devices and polyurethane springs) are investigated. All four cases are analyzed in ABAQUS platform under cyclic loadings. In addition, the SMA plates are replaced by steel ones in four cases, and the results are compared to the SMA dampers. The results show that the axial polyurethane friction (APF) damper could decrease the residual deformation effectively. Also, the damper capacity and dissipated energy could be improved. The analysis showed that APF damper is a good recentering damper with a large amount of energy dissipation and capacity, among others.

A 2D FE Model for a Unique Residual Stress in Single Shot Impact (단일 숏 충돌에서의 잔류응력 유일해를 위한 2차원 유한요소해석 모델)

  • Kim, Tae-Hyung;Lee, Hyung-Yil
    • Proceedings of the KSME Conference
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    • 2007.05a
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    • pp.183-188
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    • 2007
  • In this paper, we propose a 2D-FE model in single impact with combined physical factors to obtain a unique residual stress by shot peening. Applied physical parameters include elastic-plastic deformation of shot ball, material damping coefficients, strain rate, dynamic friction coefficients. Single impact FE model consists of 2D axisymmetric elements. The FE model with combined factors showed converged and unique distributions of surface stress, maximum compressive residual stress and deformation depth. Further, in contrast to the FE models with rigid shot and elastic deformable shot, FE model with plastic deformable shot produces residual stresses very close to experimental solutions by X-ray diffraction. We therefore validated the 2D FE model with combined peeing factors and plastic deformable shot. This FE model will be a base of the 3D FE model for residual stresses by multi-impact shot peening.

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Evaluation of Residual Stresses in 12%-Cr Steel Friction Stir Welds by the Eigenstrain Reconstruction Method

  • Jun, Tea-Sung;Korsunsky, Alexander M.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.24 no.1
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    • pp.15-22
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    • 2015
  • In the present paper we report the results of a study into Friction Stir Welds (FSWs) made in 13 mm-thick 12%-Cr steel plates. Based on residual strains obtained by diffraction techniques, eigenstrain analysis was performed using the Eigenstrain Reconstruction Method (ERM), which is a novel methodology for the reconstruction of full-field residual strain and stress distributions within engineering components. Significant eigenstrain distributions were found at around Thermo-Mechanically Affected Zone (TMAZ) where the most severe plastic deformation was occurred. Microstructure analysis was used to elucidate this phenomenon showing that the grain structure in TMAZ was bent and not successfully recrystallised, resulting in severe deformation behaviour. The reconstructed residual strain distributions by the ERM agree well with the experimental results. It was found that the approach based on theory of eigenstrain is a powerful basis for reconstructing the full-field residual strain/stress distributions in engineering components and structures.

Effect of the Leveling Conditions on Residual Stress Evolution of Hot Rolled High Strength Steels by Deformation Analysis of Leveling Process (레벨링 공정 해석에 의한 교정 조건이 열연 고장도 강판의 잔류음력에 미치는 영향 연구)

  • Park, K.C.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2009.05a
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    • pp.326-329
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    • 2009
  • In order to analyze the effect of leveling conditions on residual stress evolution of hot rolled high strength steels, a numerical algorithm was developed. It was able to implement the effect of plastic fraction (intermesh) in leveling, line tension, work roll bending, and initial residual stress and curl distribution. The effect of work roll bending on residual stress and curl were studied by using the developed program. The validity of simulated results was verified from comparison with the experimentally measured residual stress and curl in a sheet.

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Analysis of Variations in Deformations of Additively Manufactured SUS316L Specimen with respect to Process Parameters and Powder Reuse (금속 적층제조 방식을 이용한 SUS316L 시편의 공정 파라미터 및 금속 분말 재사용에 따른 변형량 변화 분석)

  • Kim, Min Soo;Kim, Ji-Yoon;Park, Eun Gyo;Kim, Tae Min;Cho, Jin Yoen;Kim, Jeong Ho
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.4
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    • pp.223-231
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    • 2022
  • Residual stress that can occur during the metal additive manufacturing process is an important factor that must be properly controlled for the precise production of metal parts through 3D printing. Therefore, in this study, the factors affecting these residual stresses were investigated using an experimental method. For the experiment, a specimen was manufactured through an additive manufacturing process, and the amount of deformation was measured by cutting it. By appropriately calibrating the measured data using methods such as curve fitting, it was possible to quantitatively analyze the effect of process parameters and metal powder reuse on deformation due to residual stress. From this result, it was confirmed that the factor that has the greatest influence on the magnitude of deformation due to residual stress in the metal additive manufacturing process is whether the metal powder is reused. In addition, it was confirmed that process parameters such as laser pattern and laser scan angle can also affect the deformation.