• Title/Summary/Keyword: plastic fine

Search Result 284, Processing Time 0.021 seconds

Rheological Models for Describing Fine-laden Debris Flows: Grain-size Effect (세립토 위주의 토석류에 관한 유변학적 모델: 입자크기 효과)

  • Jeong, Sueng-Won
    • Journal of the Korean Geotechnical Society
    • /
    • v.27 no.6
    • /
    • pp.49-61
    • /
    • 2011
  • This paper presents the applicability of rheological models for describing fine-laden debris flows and analyzes the flow characteristics as a function of grain size. Two types of soil samples were used: (1) clayey soils - Mediterranean Sea clays and (2) silty soils - iron ore tailings from Newfoundland, Canada. Clayey soil samples show a typical shear thinning behavior but silty soil samples exhibit the transition from shear thinning to the Bingham fluid as shear rate is increased. It may be due to the fact that the determination of yield stress and plastic viscosity is strongly dependent upon interstructrual interaction and strength evolution between soil particles. So grain size effect produces different flow curves. For modeling debris flows that are mainly composed of fine-grained sediments (<0.075 mm), we need the yield stress and plastic viscosity to mimic the flow patterns like shape of deposition, thickness, length of debris flow, and so on. These values correlate with the liquidity index. Thus one can estimate the debris flow mobility if one can measure the physical properties.

A Tunable Digital Tourniquet Using Nelaton Catheter (고무 도뇨관을 이용한 간단한 수지 지혈대)

  • Kim, Sang Wha;Yim, Young Min;Jung, Sung No;Kwon, Ho
    • Archives of Plastic Surgery
    • /
    • v.35 no.6
    • /
    • pp.759-761
    • /
    • 2008
  • Purpose: Surgery on digit requires a clear, bloodless field and it can be achieved by using a tourniquet. Several type of tourniquet have been used including Penrose drains and sterile glove with hemostat. We present a simple digital tourniquet using nelaton catheter, which is easily available, inexpensive, easy-to-apply, and effective for digital surgery. Methods: We made a small incision on the opposite side of an opening at the tip of nelaton catheter. Then the other tip of nelaton catheter is passed through the incision to form a ring. Nelaton catheter is placed aournd the base of the injured finger, making a tight circle to desired pressure. Results: A simple tourniquet using nelaton catheter effectively achieves a bloodless field and allows fine control of the pressure for digital surgery. Conclusion: We present a sismple digital tourniquet using nelaton catheter, which is easily available, inexpensive, tunable, and available for more than one finger.

Studies on Production of High-Quality Cornus controversa Container Seedlings (층층나무 우량 용기묘 생산에 관한 연구)

  • 윤택승;홍성각
    • Journal of Korea Foresty Energy
    • /
    • v.21 no.3
    • /
    • pp.28-33
    • /
    • 2002
  • This study was carried out to develop the technique for the production of high quality container seedlings of Comus controversa Hemsley. The seedlings were grown on the medium of peatmoss : perlite : vermiculite (1:1:1, v/v) in plastic net container and no-net plastic container as control for five months in the PE house. The seedlings grown in the plastic net container showed better root collar diameter growth, better development of long and fine roots, more increment of dry mass of roots and shoots than those grown in the no-net container. But the height growth of the seedlings in both container was similar. In particular the seedlings grown in plastic net container had no spiraling roots which were always observed in the control container seedlings. This result was induced by air-root pruning effect from the plastic net container.

  • PDF

Effect Analysis of Mix Designing Factors on Workability and Rheological Parameters of Self-Compacting Concrete (배합요인이 자기충전 콘크리트의 워커빌리티 및 레올로지 파라미터에 미치는 영향 분석)

  • Yoon, Seob;Han, Min-Cheol
    • Journal of the Korea Institute of Building Construction
    • /
    • v.18 no.3
    • /
    • pp.235-242
    • /
    • 2018
  • The objective of the paper is to investigate the effect of mix designing factors on the workability and rheological parameters of self compacting concrete in order to facilitate the difficulties of quality control of high sensitivity of SCC. Mix proportions of SCC were prepared with various conditions of coarse, and fine aggregate, and unit water content, and the SCC mixtures were tested on workability, rheological properties to provide basic data for quantitative evaluation. Test results indicated that the yield stress of SCC decreased with increasing the coarse aggregate volume ratio, and increased with increasing the amount of VMA. However, unit water content, fine aggregate type, and air content didn't affect the yield stress value. The plastic viscosity according to the mixing factors showed a similar tendency to the yield stress. In addition, there was no correlation between yield stress and workability (flow, T50, V-lot). However, there was closely correlation among plastic viscosity and T50 and V-lot. Especially, T50 and V-lot time decreased with decreasing plastic viscosity.

Sustainable controlled low-strength material: Plastic properties and strength optimization

  • Mohd Azrizal, Fauzi;Mohd Fadzil, Arshad;Noorsuhada Md, Nor;Ezliana, Ghazali
    • Computers and Concrete
    • /
    • v.30 no.6
    • /
    • pp.393-407
    • /
    • 2022
  • Due to the enormous cement content, pozzolanic materials, and the use of different aggregates, sustainable controlled low-strength material (CLSM) has a higher material cost than conventional concrete and sustainable construction issues. However, by selecting appropriate materials and formulations, as well as cement and aggregate content, whitethorn costs can be reduced while having a positive environmental impact. This research explores the desire to optimize plastic properties and 28-day unconfined compressive strength (UCS) of CLSM containing powder content from unprocessed-fly ash (u-FA) and recycled fine aggregate (RFA). The mixtures' input parameters consist of water-to-cementitious material ratio (W/CM), fly ash-to-cementitious materials (FA/CM), and paste volume percentage (PV%), while flowability, bleeding, segregation index, and 28-day UCS were the desired responses. The central composite design (CCD) notion was used to produce twenty CLSM mixes and was experimentally validated using MATLAB by an Artificial Neural Network (ANN). Variance analysis (ANOVA) was used for the determination of statistical models. Results revealed that the plastic properties of CLSM improve with the FA/CM rise when the strength declines for 28 days-with an increase in FA/CM, the diameter of the flowability and bleeding decreased. Meanwhile, the u-FA's rise strengthens the CLSM's segregation resistance and raises its strength over 28 days. Using calcareous powder as a substitute for cement has a detrimental effect on bleeding, and 28-day UCS increases segregation resistance. The response surface method (RSM) can establish high correlations between responses and the constituent materials of sustainable CLSM, and the optimal values of variables can be measured to achieve the desired response properties.

A review on the application of plastic waste in the reinforced concrete structures

  • K. Senthil;Suresh Jakhar;Manish Khanna;Kavita Rani
    • Advances in materials Research
    • /
    • v.13 no.2
    • /
    • pp.115-128
    • /
    • 2024
  • Concrete is the most significant material in the construction industry which is required to construct several facilities like roads, buildings, and bridges etc. which leads to the economic development of a country. But now days, in view of sustainable development and environmental problems, plastic waste management is one of the major environmental issues due to its non-biodegradable nature which allows it to stay in the landfills until they are cleaned up. To overcome all these concerns, plastic waste may be used as a substitute of natural fine and coarse aggregate in concrete and a valuable solution to utilize the plastic items which causes several problems. In order to, present study is focused on the affecting properties of concrete as workability, compressive strength, and tensile strength of concrete with using plastic waste and without using plastic waste. Based on the detailed literature, it was observed that the plastic waste is not affecting the quality and consistency of concrete. However, as the number of PVC particles in the mixture increased, the drying shrinkage values decreased and the inclusion of plastic flakes can mitigate drying shrinkage cracking which leads the higher durability of concrete. Based on the comprehensive literature, it was also observed that the plastic aggregate found to be suitable for low and medium strength concrete. However, the investigation on the application of plastic aggregate in the high strength concrete is found limited. It was concluded that the optimum percentage of the plastic aggregate was found about 20%.

A Study on the Steps of Shear Deformations Behavior of Fine-Blanking Process (Fine-Blanking시 전단 단계별 변형 거동에 관한 연구)

  • 이종구;박원규
    • Transactions of the Korean Society of Machine Tool Engineers
    • /
    • v.11 no.4
    • /
    • pp.26-33
    • /
    • 2002
  • One characteristic of Fine-Blanking is that the size and the direction of stress and strain are very complex in the plastic flow according to the condition of blanking. Especially, they are affected by the clearance of punch and die, by the force of blanking holder and by the force of counter punch. The purpose of this research is to how the deformation behavior in shear zone more clearly, based on Green & Cauch's large deformation theory. The deformation behavior and cracks were investigated in each step of shear, according to punch penetration increase, the use of V-indenter ring and the hardness of materials. This research found that the transforming behavior was the same as pure discretion and the cracks could be prevented when hardness is low.

Finite Element Analysis on Effect of Die Clearance on Shear Planes in Fine Blanking (파인 블랭킹에서 전단면에 미치는 다이 틈새의 영향에 관한 유한 요소 해석)

  • 김윤주;곽태수;배원병
    • Transactions of Materials Processing
    • /
    • v.9 no.2
    • /
    • pp.152-158
    • /
    • 2000
  • A finite element analysis has been performed to investigate the effect of die clearance on shear planes in the fine blanking of a part of automobile safety belt. For the analysis, S45C is selected as an material, which is used in manufacturing the part of automobile safety belt, and Cockcroft-Latham fracture criterion is applied. Effect of die Clearance on die-roll width, die-roll depth, burnish zone, and fracture zone has been investigated in the finite element analysis by a rigid-plastic FEM code, DEFORM-2D. From the analysis, it has been found that die-roll depth and depth of the shear plane increase with increasing die clearance. And the burnish zone decreases with increasing die clearance, but the variation of fracture zone is opposite to that of burnish zone because the increase in die clearance requires less fracture energy. Theoretical predictions are compared with experimental results. There is a good agreement between theory and experiment.

  • PDF

Fatigue Properties of Fine Grained Magnesium Alloys after Severe Plastic Deformation

  • Chung Chin-Sung;Chun Duk-Kyu;Kim Ho-Kyung
    • Journal of Mechanical Science and Technology
    • /
    • v.19 no.7
    • /
    • pp.1441-1448
    • /
    • 2005
  • Fine grained AZ31 and AZ61 magnesium alloys produced by equal channel angular pressing (ECAP) were tested for investigating tensile and fatigue properties, including microstructure, monotonic tensile flow, fatigue life and crack growth rate. For the two alloys, the yield stress of the ECAPed sample was lower than that of the unECAPed (=as received) sample, because of the fact that the softening effect due to texture anisotropy overwhelmed the strengthening effect due to grain refinement. Grain refinement of the AZ31 and AZ61 alloys through ECAP was found not to be significantly effective in increasing fatigue strength.

Effect of grain refinement on the performance of AZ80 Mg alloys during wear and corrosion

  • Naik, Gajanan M;Gote, Gopal D.;Narendranath, S;Kumar, S.S. Satheesh
    • Advances in materials Research
    • /
    • v.7 no.2
    • /
    • pp.105-118
    • /
    • 2018
  • Magnesium and its alloys are attracted towards all engineering applications like automotive, marine, aerospace etc. due to its inherent high strength to weight ratio. But, extensive use of Mg alloys is limited to the current scenario because of low wear and corrosion resistance behavior. However, equal channel angular press is one of the severe plastic deformation technique which has been effective method to improve the wear and corrosion resistance by achieving fine grain structure. In this study, the effect of grain refinement on wear and corrosion resistance of AZ80 Mg alloys were investigated. The wear behavior of the coarse and fine-grained Mg alloys was examined through $L_9$ orthogonal array experiments in order to comprehend the wear behavior under varies control parameters. It was shown that ECAPed alloy increased the wear and corrosion resistance of the Mg alloy through the formation of fine grain and uniform distribution of secondary ${\beta}-phase$. Also, the performance of AZ80 Mg alloy for these changeswas discussed through SEM morphology.