• Title/Summary/Keyword: shrinkage rate

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The Effect of Mixed Rate of Recycled Resin on the Shrinkage in Molded Parts (재활용 플라스틱 재료의 혼합비가 성형품 수축에 미치는 영향)

  • Kim, Young-Soo;Kim, In-Kwan;Kang, Tae-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.2 no.3
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    • pp.62-68
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    • 2003
  • In this study, an experimental work was performed to mold tensile specimens by using the injection molding machine. Melt temperature, mold temperature and the mixed rate of recycled resin were selected as processing parameters for studing the effect of those condition on the shrinkage and weight of molded parts. As a result, the shrinkage was increased with the higher mold and melt temperature and It was more senstive to the change of mold temperature. On the other hand, the weight of molded parts was decreased with the increment of mold and melt temperature.

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Evaluation of Appearance Capacity of Fabrics for Men's Suit by FAST System (FAST 시스템에 의한 신사복지의 외관성능 평가)

  • Kim, Jung-Sook
    • Fashion & Textile Research Journal
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    • v.8 no.5
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    • pp.591-596
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    • 2006
  • In order to analyze the tailorbility of different fabrics for men's suit, FAST system has been used for measuring the distribution of mechanical properties in this study. As results, cashmere mixed woolen fabrics showed the minimum degree in relaxation shrinkage, formability, and shear rigidity than any other fabrics, and also showed more than 6% as maximum level of extensibility. Thus, cashmere mixed woolen fabrics requires careful tailoring in lay-out, marking, and cutting. It is necessary to establish new tailoring criteria for automatic sewing with cashmere mixed woolen fabrics than any other fabrics, because they show more failure rate of tailorbility. There have been noticeably more variation of shrinkage and extension for woolen fabrics with cashmere mixed than 100% woolen fabrics by evaluating the formability of the suits when these are completed to suits through cutting and tailoring from fabrics. Especially nylon mixed woolen fabrics showed shrinkage overall, but polyester mixed woolen fabrics showed extension at waist area. Thus, it is necessary to adjust the appropriate overfeed rate considering the amount of shrinkage and extension while tailoring.

Prediction of Autogenous Shrinkage on Concrete by Unsaturated Pore Compensation Hydration Model (불포화 공극 보정 수화도 모델을 이용한 콘크리트의 자기수축 예측)

  • Lee, Chang Soo;Park, Jong Hyok
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5A
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    • pp.909-915
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    • 2006
  • To predict autogenous shrinkage of concrete, unsaturated pore compensation factor could be calculated by experiments of autogenous shrinkage of cement paste on the assumption that the differences between degree of hydration and strain rate of autogenous shrinkage are unsaturated pore formation rate. Applying unsaturated pore compensation factor on modified Pickket model considering contribution factor and non-contribution factor to autogenous shrinkage of concrete, experimental data and existing model were compared. From the results modified Pickket model was verified to present similar tendency between Tazawa model and experimental data, but CEB-FIP model might be corrected because this model uses ultimate autogenous shrinkage underestimated and the same autogenous time function of concrete material properties considering only compressive strength.

The Effect of Casting Conditions on Shrinkage and Porosity of A356.2 Alloys (A356.2 합금의 수축과 기공에 미치는 주조 조건의 영향)

  • Jeon, Gyu-Tae;Kim, Ki-Young;Kim, Suk-Jun
    • Journal of Korea Foundry Society
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    • v.37 no.6
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    • pp.193-198
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    • 2017
  • In this study, volumes of shrinkage and porosity of A356.2 alloys during casting were analyzed as a function of melt temperature, pouring diameter, mold temperature, and Sr content. The temperature of the melt barely affected the shrinkage and porosity formation. The pouring diameter determined the pouring rate, and it was proportional to the shrinkage, yet no relationships with the density of porosity were observed. When the mold was heated at $400^{\circ}C$, shrinkage and porosity in the alloy increased above the one in the mold without heating. However, the mold without heating experienced interior shrinkage and the porosity was mainly distributed near interior shrinkage. The addition of Sr to the melt resulted in more shrinkage and less porosity.

A Experimental Study on Autogenous Shrinkage properties of Ultra High-Strength Concrete Using Expansion Agent and Shrinkage-reducing (수축저감제 및 팽창재를 조합 사용한 초고강도 콘크리트의 자기수축 특성에 관한 실험적 연구)

  • Park, Hyun;Park, Heung-Lee;Kim, Hak-Young;Paik, Min-Su;Kim, Woo-Jae;Jung, Sang-Jin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2009.11a
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    • pp.73-76
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    • 2009
  • In ultra-high-strength concrete, chemical shrinkage is larger than drying shrinkage due to using a large amount of cement and admixtures, and this is a factor deteriorating the quality of structures. Thus, we need a new technology for minimizing the shrinkage strain of ultra-high-strength concrete. So, this study have prepared super-high-strength concrete with specified mixing design strength of over 100MPa and have evaluated a method of reducing chemical shrinkage by using expander and shrinkage-reducing agent. According to the results of this study, with regard to the change in length by chemical shrinkage, an expansion effect was observed until the age of seven days. The expansion effect was higher than previous research that used only expander or shrinkage reducing agent. In addition, ultra-high-strength concrete showed a shrinkage rate that slowed down with time, and the effect of the addition of expander material on compressive strength was insignificant. That is shown that required more database to be accumulated through experimental research for the shrinkage strain of members.

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Engineering Properties of Low Cement Mortar with type and Various Incorporating Ratios of Setting Accelerator (응결촉진제 종류 및 치환율 변화에 따른 저시멘트 모르타르의 공학적 특성)

  • Jo, Man-Ki;Han, Sang-Yoon;Cha, Cheon-Soo;Park, Yong-Kyu;Yoon, Gi-Won;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2015.11a
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    • pp.143-144
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    • 2015
  • In this research it was attempted to analyze the general engineering properties of low cement mortar according to the type of setting accelerator and substitution rate, when 1% substitution rate for setting accelerator was used a high rate of compressive strength manifestation was shown and that the WS-10 type setting accelerator was appropriate. For the rate of change of length, when 3% substitution rate for setting accelerator was used, it was shown that due to initial expansion the shrinkage compensation was not significant, and when taking into consideration strength and shrinkage, 1% of WS-10 was shown to be appropriate.

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Shrinkage rate and Structure analysis of IV according to Thermal deterioration (열열화 온도에 따른 IV의 수축률 및 조직분석)

  • Choi, Chung-Seog;Kim, Hyung-Rae;Song, Kil-Mok;Kim, Hyang-Kon;Kim, Dong-Ook;Kim, Dong-Woo
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1416-1418
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    • 2002
  • In order to examine the thermal properties of the wire materials, we analyzed the shrinkage, the expansion and the form transformation, the surface structure according to the thermal deterioration temperature through the testing method for a heating shrinkage of Korean Industrial Standard(KS C 3004). For IV(600V grade polyvinyl chloride insulated wires), we measured the shrinkage and the expansion rate, analyzed the surface structure using SEM(Scanning Electron Microscope). In the result of this experiment, the shrinkage rate of IV 2.0mm covering was high in comparison with other wires. As the deterioration temperature rises gradually, the covering is molten and harden.

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A Study on Compressive Strength of Concrete Exposed to Evaporation Immediately After Casting (성형직후 증발작용을 받은 콘크리트의 강도에 대한 연구)

  • 오무영
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.16 no.4
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    • pp.3545-3554
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    • 1974
  • The objective of this study was to investigate the characteristics of the evaporation rate, the plastic shrinkage and the compressive strength of concrete exposed to a rapid evaporation environment immediately after casting. Drying of concrete were conducted under a controlled chamber in which the temperature was mainfoimed at 30 ${\pm}$1$^{\circ}C$, the relative humidity 22 ${\pm}$1 percent, and the wind velocity 7 ${\pm}$1 m/sec. The compressive strength of concrete was tested after 28 days of standard curing. The results obtained are as follows: 1. The evaporation rate was the highest at the very beginning, was decreased as the drying progresses, and was kept almost constant after 6 hours. 2. The shrinkage of concrete was changed in three different rates for the concrete mixture having its slump vallue between 3.0cm and 7.5cm. 3. The plastic shrinkage was ended within 5 or 6 hours after casting, regardless of the water cement ratio. 4. The shrinkage was increased within the limit of slump values between 3.0cm and 7.5cm as the water-cement ratio was increased. 5. The evaporation was kept on even after the plastic shrinkage was ended. 6. Within the limit of good workability (slump value between 4.5cm and 7.5cm), the compressive strength of concrete was increased when the shrinkage rate was slow but it was decreased when the rate was rapid 7. From the result of this study it is recommended that (1) the water-cement ratio should be less as long as the workability of concrete is allowable; (2) the evaporation should be prevented at least for 4 hours after casting concrete.

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A Study on injection mold shrinkage estimates (사출 금형 수축률 산정에 관한 연구)

  • Choi, Gwang-Hyeck;Han, Seong-Ryeol;Lee, Chun-Kyu
    • Design & Manufacturing
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    • v.10 no.3
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    • pp.30-33
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    • 2016
  • It is true that the plastic shrinkage is inevitable. Shrinkage rate in effect at the time of mold design will soon determine the size of the global product. Process for the shrinkage of the plastic that provides how made, yet it has identified a process for making the question whether the shrinkage that can be trusted, and by the experimental results were as follows: as shrinkage, see ISO but, according to circumstances the process can go to the agreement between the parties. shrinkage ratio of the pressure sensor installed in the specimen mold is essential, amount of pressure sensor is that it is appropriate approximately 2-3. proper holding pressure is a significant effect on shrinkage Mitch, so that the effect of selecting the contraction ratio data according to the appropriate holding pressure during mold making. shrinkage CAE analysis results are difficult to utilize in the mold-making chamber. Based on these results, it concluded by looking forward to the improved products produced shrinkage.

Critical Compressive Strain of Concrete under a Long-Term Deformation Effect Part I. Experiments

  • Nghia, Tran Tuan;Chu, In-Yeop;Kim, Jin-Keun
    • International Journal of Concrete Structures and Materials
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    • v.4 no.2
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    • pp.89-96
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    • 2010
  • This paper focuses on the effect of creep on the critical compressive strain (CCS) of concrete. The strain of concrete corresponding to the peak compressive stress is crucial in the selection of the ultimate yield strength of the reinforcing bar used in reinforced concrete columns. Among the various influencing factors, such as the creep, shrinkage, loading rate and confinement, the effect of creep and shrinkage is the most significant. So far, investigations into how these factors can affect the CCS of concrete have been rare. Therefore, to investigate the effect of creep and shrinkage on CCS, an experimental (part I) and a parametric study (part II) were conducted, as presented in these papers (part I considers creep effect, part II considers effect of creep and shrinkage). In part I, experiments pertaining to the loading age, loading rate, loading duration and loading and creep levels were conducted to study the effect of these variables on the CCS of concrete. It was found that the effects of the loading rate, loading age, and level and duration on the CCS of concrete were negligible. However, it is very important to consider the effect of creep.