• Title/Summary/Keyword: softening effect

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Evolution of post-peak localized strain field of steel under quasi-static uniaxial tension: Analytical study

  • Altai, Saif L.;Orton, Sarah L.;Chen, Zhen
    • Structural Engineering and Mechanics
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    • v.83 no.4
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    • pp.435-449
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    • 2022
  • Constitutive modeling that could reasonably predict and effectively evaluate the post-peak structural behavior while eliminating the mesh-dependency in numerical simulation remains to be developed for general engineering applications. Based on the previous work, a simple one-dimensional modeling procedure is proposed to predict and evaluate the post-peak response, as characterized by the evolution of localized strain field, of a steel member to monotonically uniaxial tension. The proposed model extends the classic one-dimensional softening with localization model as introduced by (Schreyer and Chen 1986) to account for the localization length, and bifurcation and rupture points. The new findings of this research are as follows. Two types of strain-softening functions (bilinear and nonlinear) are proposed for comparison. The new failure criterion corresponding to the constitutive modeling is formulated based on the engineering strain inside the localization zone at rupture. Furthermore, a new mathematical expression is developed, based on the strain rate inside and outside the localization zone, to describe the displacement field at which bifurcation occurs. The model solutions are compared with the experimental data on four low-carbon cylindrical steel bars of different lengths. For engineering applications, the model solutions are also compared to the experimental data of a cylindrical steel bar system (three steel bars arranged in series). It is shown that the bilinear and nonlinear softening models can predict the energy dissipation in the post-peak regime with an average difference of only 4%.

Simulating Nuetron Irradiation Effect on Cyclic Deformation and Failure Behaviors using Cold-worked TP304 Stainless Steel Base and Weld Metals (냉간가공된 TP304 스테인리스강 모재와 용접재를 이용한 반복 변형 및 손상 거동에 미치는 중성자조사 영향 모사)

  • Kim, Sang Eun;Kim, Jin Weon
    • Transactions of the Korean Society of Pressure Vessels and Piping
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    • v.16 no.2
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    • pp.58-67
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    • 2020
  • This study presents cyclic stress-strain and tensile test results at room temperature (RT) and 316℃ using cold-worked TP304 stainless steel base and weld metals. By comparing the cyclic hardening/softening behavior and failure cycle of cold-worked materials with those of irradiated austenitic stainless steels, the feasibility of simulating the irradiation effect on cyclic deformation and failure behaviors of TP304 stainless steel base and weld metals was investigated. It was found that, in the absence of strain-induced martensite trasformation, cold-working could properly simulate the change in cyclic hardening/softening behavior of TP304 stainless steel base and weld metals due to neutron irradiation. It was also recognized that cold-working could adequately simulate the reduction in failure cycles of TP304 stainless steel base and weld metals due to neutron irradition in the low-cycle fatigue region.

Computational and mathematical simulation for the size-dependent dynamic behavior of the high-order FG nanotubes, including the porosity under the thermal effects

  • Huang, Xiaoping;Shan, Huafeng;Chu, Weishen;Chen, Yongji
    • Advances in nano research
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    • v.12 no.1
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    • pp.101-115
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    • 2022
  • Some researchers pointed out that the nonlocal cantilever models do not predict the dynamic softening behavior for nanostructures (including nanobeams) with clamped-free (CF) ends. In contrast, some indicate that the nonlocal cantilever models can capture the stiffness softening characteristics. There are substantial differences on this issue between them. The vibration analysis of porosity-dependent functionally graded nanoscale tubes with variable boundary conditions is investigated in this study. Using a modified power-law model, the tube's porosity-dependent material coefficients are graded in the radial direction. The theory of nonlocal strain gradients is used. Hamilton's principle is used to derive the size-dependent governing equations for simply-supported (S), clamped (C) and clamped-simply supported (CS). Following the solution of these equations by the extended differential quadrature technique, the effect of various factors on vibration issues was investigated further. It can be shown that these factors have a considerable effect on the vibration characteristics. It also can be found that our numerical results can capture the unexpected softening phenomena for cantilever tubes.

폐암(肺癌)의 한의치료(韓醫治療)에 관(關)한 문헌적(文獻的) 고찰(考察)

  • Park, Jeong-Hui;Kim, Byeong-Tak;Kim, Seong-Hun
    • The Journal of Korean Medicine
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    • v.16 no.1 s.29
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    • pp.71-95
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    • 1995
  • To be helpful to the treatment of pulmonary cancer with oriental medicine, we got clinical reports together and analyzed the data. The results were obtained as follows: 1. The treating methods could be summarized as three methods that were reinforcing vital energy, eliminating harmful Qi, and reinforcing vital energy with eliminating harmful Qi. The methods of reinforcing vital energy were supplementing Qi & Yin, increasing pahological heat & reinforcing kidney, augmenting Qi & blood, supplementing vital energy and strengthening fundermental energy, reinforcing spleen and increasing Qi, lubricate Yin and lung, and the other methods of eliminating harmful Qi were transforming pathological fluid and softening, clarifying heat and eliminating poison, dipersing lung and softening, toxicding and softening, guiding Qi and activating blood, clarifying heat and dispersing lung, guiding Qi and counteracting stress etc., and the methods of supplementing vital energy with eliminating poison were reinforcing spleen and transforming pathological fluid, increasing Qi and activating blood, supplementing Yin and clarifying heat, reinforcing spleen and dry the dampness, lubricating lung and transforming patholigical fluid and supplementing Qi and activating blood. 2. The oriental prescriptions used for pulmonary cancer were Chunkeum-Weekyungtang & Sohamhwingtang, Jinhayookgunjatang, Hyulboochukeotang, Bokbangkyogonamtang was reported to be effective in the treatment of metastasis. 3. Bokbangshinjingtang and haewool were applied for the complications of pulmonary cancer, Soshihotang for fever, hangamryung for tumor pain. Prunus ansu Komarov, Eriobotrya japonica Lirdley, Pyrrosiae lingua Farwel, Steomon japonica Miguel, Maximowiczia chinensis Ruprecht var, Morus bombycis Koidzumi for cough, Panax Pseudo-ginseng Wall. var, Bletilla striata Reichenbach f., Acacia catechu(兒茶) for hemoptysis, Lonicerae flos, Aspongopus chinensis(九香蟲) for chest pain, Cypsum Fibrosum, Gazella gutturosa, Scutellaria baicalensis Georgi, Gypsophila oldhamiana Miquel for fever, Lepidii semen descurainiae semen, Belamcanda chinensis D.C, Gnaphalium affine(佛耳草) for asthma. 4. For the reduction of side effect by chemotherapy and radiotherapy it was known that supplementing Qi was used chiefly for side effect of chemotherapy and augmenting Yin applied to side effect of radiotherapy. 5. The oriental presciptions were suggested for the side effect by chemotherapy and radiotherapy ; Sammaekaek(參麥液), Whaebokwontang(化瘀復元湯), Hwangjungomitang(黃精五味湯), Yukmijihwangtang(六味地黃湯), Hyangsayukgunjatang(香砂六君子湯), Samlyeekulsan for side effect by chemotherapy while Geumgweisingiwhan, Hwanglyentang(黃連湯), Hwanglyenhaedoktang(黃連解毒湯), Yangyeunchungpeitang(養陰淸肺湯), Idongtang(二冬湯), Jayeunkanghwatang(滋陰降火湯) for side effect by radiotherapy.

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Studies on Softening Stability of Softened Sea Tangle Depending on Various Softening Agents (연화제의 종류에 따른 다시마의 연화 안정성에 관한 연구)

  • 송재철;박현정
    • The Korean Journal of Food And Nutrition
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    • v.17 no.2
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    • pp.193-198
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    • 2004
  • This study was carried out to develop the intermediate material for its processing product of sea tangle by investigating softening stability of softened sea tangle for storage. The change of softening stability, Avrami (equation) exponent, color and sensory characteristics was examined during storage when hydrophilic softening agent was added to the softened sea tangle. Inclination of the sample added with isomalto oligosaccharide showed the lowest value in relation of ln(E$\_$L/- Et) vs t for four days of storage. Exponent range of Avrami equation was 1.00-1.67 and isomalto oligosaccharide having 1.0 of exponent exhibited the most stable effect in softerness. The sample formulated with isomalto oligosaccharide indicated the lowest value in rate constant and its rigidity was progressed very slowly during storage. The L, a and b value of softened sea tangle during storage was relatively decreased. Color preference, odor, cohesiveness, softerness, process compatibility were revealed to be in best when isomalto oligosaccharide was added. When softening agent was added to the softened sea tangle it showed the positive result in processing compatibility and the available value in intermediate material for its processing product. It was relatively effective on softening stability when isomalto oligosaccharide was added to the softened sea tangle.

A Study on HAZ Softening Characteristics of Fiber Laser Weldment for High-Strength Steel (고장력강 파이버 레이저 용접부의 HAZ 연화 특성에 관한 연구)

  • Park, Min-Ho;Kim, Ill-Soo;Lee, Jong-Pyo;Jin, Byeong-Ju;Kim, Do-Hyeong;Kim, In-Ju;Kim, Ji-Sun
    • Journal of Welding and Joining
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    • v.33 no.6
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    • pp.27-35
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    • 2015
  • Laser welding sector in the automotive industry has been widely recognized as one of the most important bonding processes, such as parts welding. Efforts to improve productivity and weld quality have been progressing steadily. In addition, laser welding is suitable for welding process that can produce high-quality welds suitable for flexible production and small quantity batch productions. In order to ensure the rigidity of the material, high strength material are applied to more than 1 GPa class body parts and automotive bumper beams. However, not only the situation is that the trend of domestic research, but also development is based on product molding considering freedom of shape where reinforcement is applied to meet the safety regulations and high-speed crash performance, despite the use of high strength materials. The tendency for heat-affected zone (HAZ) softening phenomenon common in areas of laser welded high tensile steel welding confirmed the occurrence of weld softening effect according to the process parameters. Based on this, range of process parameters could be selected for ensuring weld quality.

Analytical Study on the Strain Localization of Concrete (콘크리트의 변형률국소화에 관한 해석적 연구)

  • Song, Ha-Won;Seo, Chul
    • Magazine of the Korea Concrete Institute
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    • v.8 no.2
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    • pp.129-138
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    • 1996
  • Localization of concrete is a phenomenon such that the deformation of concrete is localized in finite region with softening behavior and it governs ultimate load of concrete. In this Paper, concrete under strain localization was modeled with localization region and non-localization region and lc~calization behavior was formulated based on averaging concept of heterogeneous material. By using the formulation, the localization phenomena of concrete under uniaxial loadings were well predicted. The analytical results show that size of localization region of concrete under uniaxial compression is three times of maximum aggregate size and the size effect of concrete is well predicted. The use of tension-softening curve obtained from direct tension test is suitable for well prediction of localization of concrete under uniaxial tension.

Work Softening Behavior of Zn-15%Al alloy (Zn-15%Al 합금의 가공연화 거동)

  • Jun, Joong-Hwan;Seong, Ki-Duk;Kim, Jeong-Min;Kim, Ki-Tae;Jung, Woon-Jae
    • Journal of the Korean Society for Heat Treatment
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    • v.18 no.1
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    • pp.18-23
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    • 2005
  • Effect of cold rolling on microstructural changes has been investigated for a Zn-15%Al alloy to elucidate the reason for its work softening behavior. Fully annealed microstructure of the Zn-15%Al alloy is characterized by ${\eta}$ grains and (${\eta}+{\alpha}$) lamellar colonies, where ${\eta}$ and ${\alpha}$ are Zn-rich HCP and Al-rich FCC phases, respectively. The hardness decreases continuously with increasing cold rolling degree, exhibiting work softening behavior. It is revealed that during the cold rolling, (${\eta}+{\alpha}$) lamellar colonies gradually change into equiaxed ${\eta}$ and ${\alpha}$ grains due to dynamic recrystallization at room temperature, while pre-existing ${\eta}$ grains are only deformed without recrystallization. Furthermore, cold rolling causes the precipitation of dissolved Al solutes in ${\eta}$ grains. In view of these results, change of (${\eta}+{\alpha}$) phases from lamellar to equiaxed morphology, which results in structural softness and increase in equiaxed ${\eta}/{\alpha}$ grain boundaries with higher mobility, and deterioration of solution hardening by precipitation of Al solutes from ${\eta}$ grains, are thought to contribute to the work softening of Zn-15%Al alloy.

Thermo-rheological behaviors of Phenolic Resins Blended with Petroleum-based Pitches for High Temperature Carbon Composites (석유계 피치가 첨가된 고온 탄소복합재용 페놀수지의 열 유변학적 거동 연구)

  • Yang, Jae-Yeon;Kuk, Yun-Su;Seo, Min-Kang;Kim, Byoung-Suhk
    • Composites Research
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    • v.33 no.6
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    • pp.329-335
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    • 2020
  • In this study, the thermo-rheological behaivors of petroleum pitches with different softening points were studied, and a B-stage phenolic resins/petroleum pitches blends were prepared by adding petroleum pitches to the phenolic resins. As a result, the petroleum pitch with different softening points decreased the fluidity of the petroleum pitch as the Quinoline insoluble (QI) content increased and showed the viscous properties of the solid. In addition, the effect of adding petroleum pitches having different softening points on the thermo-rheological properties of phenolic resins was investigated. When petroleum pitch with a high softening point was added, the fluidity of the phenolic resin was reduced, and the hardening behavior was fast. It was possible to control the curing rate and curing behavior of the phenolic resin by adding petroleum pitches of different softening points. Among them, the phenolic resin mixture to which P-Pitch 2 was added has a higher fluidity than other blends under the same curing temperature condition.

The Combined Effect of Enzyme Activity and Sensory Test of Blanching and Brining in Hot Solution and Trehalose Treatment on the Cucumber Kimchi for the Storage Period (데침과 열수의 침적과 Trehalose 처리가 오이 김치의 저장중 효소 활성의 변화와 관능 검사에 미치는 병용효과)

  • 이혜정;오봉희;남정혜
    • The Korean Journal of Food And Nutrition
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    • v.14 no.5
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    • pp.385-390
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    • 2001
  • The enzyme activity and organoleptic properties of Korean pickled cucumber were studies for their changes during fermentation. The Korean pickled cucumber were prepared by blanching and high temperature soaking in salt solution and trehalose treament. The results showed that the effect of combined heat and trehalose treatment significantly reduced the fermentation rate and softening rate of texture while a rather rapid fermentation was for those preserved with salt. The effect of terhalose treatment enhanced fermentation and it was significantly reduced softening rate of texture by 2% treatment. The sensory evaluation of Korean pickled cucumber was found that combined heat treatment with blanching and hot solution had a positive effect for reduction of softening of cucumber tissue, however, odor and taste were not significantly affected. This study suggested that combined heat and trehalose treament might have potential for affording protection against softness of cucumber tissue during the fermentation time.

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