• Title, Summary, Keyword: strain

Search Result 19,867, Processing Time 0.073 seconds

Influence of Strain Rate on Tensile Properties and Dynamic Strain Aging of an Fe-24.5Mn-4Cr-0.45C Alloy (변형률 속도에 따른 Fe-24.5Mn-4Cr-0.45C 합금의 인장 특성과 동적 변형시효)

  • Lee, Seung-Yong;Hwang, Byoungchul
    • Korean Journal of Materials Research
    • /
    • v.26 no.5
    • /
    • pp.281-286
    • /
    • 2016
  • In the present study, the tensile properties and dynamic strain aging of an Fe-24.5Mn-4Cr-0.45C alloy were investigated in terms of strain rate. During tensile testing at room temperature, all the stress-strain curves exhibited serrated plastic flows related to dynamic strain aging, regardless of the strain rate. Serration appeared right after yield stress at lower strain rates, while it was hardly observed at high strain rates. On the other hand, strain-rate sensitivity, indicating a general relationship between flow stress and strain rate at constant strain and temperature, changed from positive to negative as the strain increased. The negative strain-rate sensitivity can be explained by the Portevin Le Chatelier effect, which is associated with dynamic strain aging and is dependent on the strain rate because it is very likely that the dynamic strain aging phenomenon in high-manganese steels is involved in the interaction between moving dislocations and point-defect complexes.

Effect of Strain Rate on the Deformation and Cracking Behaviors of ITO/PET Sheets with 45 ohms/sq. Sheet Resistance (면저항 45 ohms/sq.의 ITO/PET Sheets의 변형률 속도에 따른 균열 형성 거동)

  • Kim, Jin-Yeol;Hong, Sun-Ig
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.22 no.1
    • /
    • pp.67-73
    • /
    • 2009
  • The stress-strain behavior and its effects on the crack initiation and growth of ITO film on PET substrate with a sheet resistance of 45 ohms/sq were investigated. Electrical resistance increased gradually at the strain of 0.7% in the elastic to plastic transition region of the stress strain curves. Numerous cracks were observed after 1% strain and the increase of the resistance can be linked to the cracking of ITO thin films. The onset strain for the increase of resistance increased with increasing strain rate, suggesting the crack initiation is dependent on the strain rate. Upon loading, the initial cracks perpendicular to the tensile axis were observed and propagated the whole sample width with increasing strain. The spacing between horizontal cracks is thought to be determined by the fracture strength and the interfacial strength between ITO and PET. The crack density increased with increasing strain. The spacing between horizontal cracks (perpendicular to the stress axis) increased with decreasing strain rate, The increase of crack density with decreasing strain rate can be attributed to the higher fraction of the plastic strain to the total strain at a given total strain. As the strain increased over 5% strain, cracks parallel to the stress axis were developed and increased in number with strain, accompanied by drastic increases of resistance.

A Study on the Measurement Methods of Plastic Strain Ratio in Automotive sheet steel (자동차용 강판의 소성변형비 측정 방법 연구)

  • 김인수;김인수
    • Proceedings of the Korean Society for Technology of Plasticity Conference
    • /
    • /
    • pp.85-92
    • /
    • 1996
  • The Measurement method of the plastic strain ratio is various in Automotive sheet steel. In this paper, the measurement of the plastic strain are used two different methods, ASTM E 517 method and the automatic strain measurement tensile specimen during the tensile test, and compared the plastic strain ratios from the two methods. The experimental results showed that the measured plastic strain ratios from the automatic strain measurement method are coincide with that from the ASTM E 517 standard measurement in various specimens. Therefore, automatic strain measurement method by two extensometers shows good accuracy. Also, the strain dependance of plastic strain ratios could be recorded by the computer continuously and anisotropy of the strength coefficient, K, and strain hardening exponent, n ,could be compared with each direction automatically through the use of automatic strain measurement system.

  • PDF

팔프 및 제지공장 폐수의 처리에 관한 미생물학적 연구 1

  • 홍순우;하영칠;강영화
    • Korean Journal of Microbiology
    • /
    • v.10 no.1
    • /
    • pp.9-28
    • /
    • 1972
  • 1. To get the suitable yeasts for the tratment of waste liquor from pulp and paper industries, the 162 yeasts were isolated from the waste liquor, decayed trees and sewage (1, 7, 8, 9, 1971). 17 species were chosen by its ability to assimilate the carbon compounds and indentified. 2. All of the strain was increased its growing ability by agitation. In particular, the strain 912, strain 613, strain 100, strain 732 showed excellent high productive ratio(A/$A_{0}$). 3. The optimum temperature of the strains rangel $27^{\circ}C$ and $30^{\circ}C$. 4. Most of the strain was grown actively in 10C/5N-composition and strain 113, strain 432, strain 735, strain 936, and strain 912 showed its optimum growing in 15C/5N-composition and 5C/5N-composition, respectively. 5. The optimum pH of the strains lay within range pH 4.5-6. Effect of the variation of pH on the growth was nearly negligible within this range. 6. The strain 912, strain 100, strain 613, strain 311, strain 235, and strain 732 were expected for the utilization to the treatment of the waste liquor from pulp and paper industries.

  • PDF

Residual Strain Effect on Circumferential Strain on Arterial Cross-Section (동맥 전단부에 분포된 원주 변형율에 대한 잔유 변형율의 영향)

  • 황민철;신정욱
    • Journal of Biomedical Engineering Research
    • /
    • v.16 no.3
    • /
    • pp.325-330
    • /
    • 1995
  • The distribution of circumferential strain of arterial cross-section Is highest at intima and lowest at adventitia. However, the circumferential strain is theoretically severe at Intima because there is strain concentration. The theoretical degree of the intimal strain can not be explained in physiological condition even though artery is physiologically normal. Physiological adaptation may be undertaken to strain concentration. However, it is not clear, yet. Residual strain of artery is eagerly studied. There is experimental evidence that residual strain exists in artery. When ring of artery is longitudinally cut, it is opened. Assumption is made that intimal strain concentration is reduced with the considel'ation of residual strain. This study experimentally attempts to quantify the effect of residual strain on circumferential strain which is determined under the assumption of zero strain with zero pressure.

  • PDF

The Influence of Temperature and Strain Rate on the Mechanical Behavior in Uranium

  • Lee, Key-Soon;Park, Won-Koo
    • Nuclear Engineering and Technology
    • /
    • v.10 no.2
    • /
    • pp.73-78
    • /
    • 1978
  • The effect of temperature and strain rate on the deformation behavior of $\alpha$-uranium was investigated in the temperature ranged 300$^{\circ}$ to 55$0^{\circ}C$ by strain, rate change test. Strain rate sensitivity, activation volume, strain rate sensitivity exponent and dislocation velocity exponent were determined. The strain rate sensitivity exponent and dislocation velocity exponent were determined. The strain rate sensitivity exponent increases with strain below 40$0^{\circ}C$, while the exponent decreases with strain above 50$0^{\circ}C$. It is believed that the increase of strain rate sensitivity exponent with strain below 40$0^{\circ}C$ can be attributed to an increase in internal stress as a result of work hardening while decrease of the exponent with strain above 50$0^{\circ}C$ is due to predominance of thermal softening over work hardening because more slip, system are active in deformation above about 50$0^{\circ}C$.

  • PDF

Development of a Paper Strain Gauge using Inkjet-printing Technology (잉크젯 인쇄기술을 이용한 종이 스트레인게이지 개발)

  • Lee, Young Tae
    • Journal of the Semiconductor & Display Technology
    • /
    • v.14 no.2
    • /
    • pp.23-27
    • /
    • 2015
  • In this paper, eco-friendly paper strain gauge was fabricated in the way of printing strain gauge on paper substrate, using PEDOT:PSS ink and inkjet printer technology. As a p-type conductive high polymer, PEDOT:PSS is known to be piezoresistive effect. I formed a strain gauge by connecting in parallel 5 lines of $60{\mu}m$ width printed with PEDOT:PSS. To minimize surrounding influence such as temperature, I formed wheat-stone bridge by combining 4 strain gauges (quarter-bridge strain gauge) which were made up of PEDOT:PSS 5 lines and measured. In quarter-bridge strain gauge, only two strain gauges, facing each other, arranged in strain and horizontal direction were deformed while the other two strain gauge of vertical direction were not. Therefore, quarter-bridge strain gauge showed the output of half bridge. The fabricated quarter-bridge strain gauge had output sensitivity of $105.6{\mu}V/V{\cdot}mm$ and its output linearity was relatively good.

Research on Residual Strain of Arterial Cross-Section (동맥 전단부에 분포된 원주 변형율에 대한 잔유 변형율의 영향)

  • Whang, Min-Cheol;Shin, Jung-Woog
    • Proceedings of the KOSOMBE Conference
    • /
    • v.1995 no.11
    • /
    • pp.151-153
    • /
    • 1995
  • Residual strain of artery is studied. There has been experimental evidence that residual strain exists in artery. When ring of artery is longitudinally cut, it is opened. Since strain has been determined without considering residual strain, the existence of residual strain is meaningful in mechanics of arterial wall. Intimal strain concentration is considered to be reduced with both account of residual strain and strain determined by loading. However, it is lack of experimental research. Therefore, this study experimentally attempts to quantify the effect of residual strain on circumferential strain which is determined under the assumption of zero strain with zero pressure.

  • PDF

The Effect of Dynamic Strain Aging on the High Temperature Plastic Deformation Behaviour of Al-Mg Alloy (Al-Mg 합금의 고온 소성 변형 특성에 미치는 동적 변형 시효의 영향)

  • 이상용;이정환
    • Transactions of Materials Processing
    • /
    • v.5 no.4
    • /
    • pp.327-336
    • /
    • 1996
  • The effect of dynamic strain aging on high temperature deformation behaviour of the A-Mg alloy was investigated by strain rate change tests and stress relaxation tests between 20$0^{\circ}C$and 50$0^{\circ}C$. Yield point, short stress transient and periodic discontinuities on the stress-strain curve were considered as an evidence of the effect of dynamic strain aging. With this criterion two distinct strain rate-temperature regimes could be manifested. Dynamic strain aging was considered to be effective in the high temperature-low strain rate regime, whereas dynamic recovery was a dominant deformation mechanism in the low temperature-high strain rate regime. It was found that dynamic strain aging in the high temperature deformation was governed by the mechcanism of diffusion-controlled, viscous dislocation movement.

  • PDF

Interpretation of coefficient of consolidation from CRS test results

  • Jia, Rui;Chai, Jinchun;Hino, Takenori
    • Geomechanics and Engineering
    • /
    • v.5 no.1
    • /
    • pp.57-70
    • /
    • 2013
  • Constant rate of strain (CRS) consolidation tests were conducted for undisturbed Ariake clay samples from three boreholes in Saga Plain of Kyushu Island, Japan. The coefficients of consolidation ($c_{\nu}$) were interpreted from the CRS test results by small- and large-strain theory. Large-strain theory was found to interpret smaller $c_{\nu}$ values and less strain rate effect on $c_{\nu}$ than that by small-strain theory. Comparing the theoretical strain distributions within a soil specimen to those obtained by numerical simulation shows that the small-strain theory can be used only for the dimensionless parameter $c_{\nu}/\dot{\varepsilon}H_0^2{\geq}50$ (where $\dot{\varepsilon}$ is strain rate and $H_0$ is the specimen height), and the large-strain theory can be used for a larger range of strain rates. Applying the criterion to undisturbed Ariake clay with a $c_{\nu}$ value of about $1{\times}10^{-7}\;m^2/s$, it is suggested that the large-strain theory should be adopted for calculating the $c_{\nu}$ value when $\dot{\varepsilon}$ > 0.03%/min.