• Title, Summary, Keyword: compressive strain

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The Effect of Repetitive Compression with Constant Stress on the Compressive Properties of Foams (일정 응력 반복압축이 발포체의 압축 특성에 미치는 영향)

  • Park, Cha-Cheol
    • Elastomers and Composites
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    • v.40 no.4
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    • pp.258-265
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    • 2005
  • To study the compressive stress, recovery force and permanent strain of foams for footwear midsole, polyurethane(PU), phylon(PH) and injection phylon(IP) foams were repetitively compressed with constant compressive stress. Maximum compressive stress of PU did not decrease with repetitive compression on the constant compressive stress, but that of IP largely decreased. Engineering strain of foams were formed by repetitively compressing the three types of foam. The engineering strain of PU was smaller than that of IP and PH. Compressive stress and recovery force of IP and PH at certain strain were decreased with repetitive compression, but that of PU was not noticeably changed.

Effect of Strain Rate on the Mechanical Properties of High Performance Fiber-Reinforced Cementitious Composites (재하속도에 따른 고성능 섬유보강 시멘트 복합체의 역학적 특성)

  • Yun Hyun-Do;Yang Il-Seung;Han Byung-Chan;Hiroshi Fukuyama;Cheon Esther;Kim Sun-Woo
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.29-32
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    • 2004
  • An experimental investigation of the behavior of steel cords(SC) and SC and Polyethylene(PE) hybrid fiber reinforced cementitious material under compressive and tensile loading is presented. In this experimental research, the tensile and compressive strength and strain capacity of high performance fiber-reinforced cementitious composites(HPFRCC) were selected using the cylindrical specimens. Uniaxial compressive and tensile tests have also been carried out at varying strain rates to better understand the behavior of. HPFRCC and propose the standard loading rate for compressive and tensile tests of new HPFRCC materials. The results show that there is a substantial increase in the ultimate compressive and tensile strength with increasing strain rate.

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The effect of compressive strain rate on biaxial compressive deformation characteristics of Al circular pipe (AI 원형 관의 2축 압축 변형특성에 미치는 압축속도의 영향)

  • Won, S.T.;Jung, H.J.;Ahn, H.J.;Cho, H.H.;Yoo, C.K.
    • 한국금형공학회:학술대회논문집
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    • pp.23-26
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    • 2008
  • In order to examine the deformation characteristics of Al circular pipe underthe biaxial compression, the horizontal biaxial compression die for the experiment was manufactured. From this, in the various compressive strain rate (1 mm/min. ${\sim}$ 400 mm/min.)conditions, the circular pipes, which were made by Al materials, were investigated based on the properties change of cross section area, punch load and deformation behavior. The tensile and compressive strains were evaluated from micro Vickers hardness tester. From these results, the punch load and deformation characteristic of Al circular pipes were highly changed in the compressive strain rate about 200 mm/min. The Al circular pipes had the tendency that the punch load decreased with increasing the compressive strain rate. In addition, following as the change of the shape and position of neutral axis due to the deformation proceeding of the circular pipe, the special point of the internal circular pipe at maximum load showed the maximum deformation strain and the maximum measured hardness value. The CAE (computer aided engineering) simulation using Deform-2D program was performed on the circular pipe in order to know and verify the exact compressive deformation behavior. From these results, the experimentally measured results were reasonably in good agreement with the simulation results.

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Experimental Investigation on the Mechanial Behavior of Graphite/Epoxy Composites Under Hydrostatic Pressure (고압하에서의 적층복합재의 기계적 거동에 대한 실험적 고찰)

  • Rhee, K.Y.;Pae, K.D.
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.20 no.8
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    • pp.2431-2435
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    • 1996
  • In order to determine the effects of hydrostatic pressure on the mechanical behavior of graphite fiber reinforced composites, the modulus, fracture stress(maximum stress), and fracture strain of graphite/epoxy composites have been determined as a function of pressure. Composite specimens used in this study were 90-deg unidirectional and had a 60% fiber volume fraction. Compressive tests under five different pressure levels were conducted. The result showed the modulus measured from as initial slope of stress-strain curve increased bilinearly with pressure with a break at 200 MPa. It was also found that fracture stress and fracture strain increased in a linear fashion with pressure.

Stress-strain Model of Laterally Confined High-strength Concrete with the Compressive Fracture Energy (압축파괴에너지를 도입한 횡구속 고강도 콘크리트의 응력-변형률 모델)

  • Hong, Ki-Nam;Shim, Won-Bo
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.54-62
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    • 2019
  • In this paper, a stress-strain model for high-strength confined concrete is proposed using compressive fracture energy. In the compression test performed by author in Reference [6], an acrylic bar with strain gauges was embedded in the center of the specimen to measure the local strain distribution. It was found from the test that the local strain measurement by this acrylic rod is very effective. The local fracture zone length was defined based on the local strain distribution measured by the acrylic rod. Specifically, it was defined as the length where the local strain increases more than twice of the strain corresponding to maximum stress. In addition, the stress-strain relationship of confined concrete with compressive fracture energy is proposed on the assumption that the amount of energy absorbed by the compressive members subjected to the given lateral confining pressure is constant regardless of the aspect ratio and size. The proposed model predicts even results from other researchers accurately.

Compressive behavior of concrete under high strain rates after freeze-thaw cycles

  • Chen, Xudong;Chen, Chen;Liu, Zhiheng;Lu, Jun;Fan, Xiangqian
    • Computers and Concrete
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    • v.21 no.2
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    • pp.209-217
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    • 2018
  • The dynamic compressive behavior of concrete after freezing and thawing tests are investigated by using the split Hopkinson pressure bar (SHPB) technique. The stress-strain curves of concrete under dynamic loading are measured and analyzed. The setting numbers of freeze-thaw cycles are 0, 25, 50, and 75 cycles. Test results show that the dynamic strength decreases and peak strain increases with the increasing of freeze-thaw cycles. Based on the Weibull distribution model, statistical damage constitutive model for dynamic stress-strain response of concrete after freeze-thaw cycles was proposed. At last, the fragmentation test of concrete subjected to dynamic loading and freeze-thaw cycles is carried out using sieving statistics. The distributions of the fragment sizes are analyzed based on fractal theory. The fractal dimensions of concrete increase with the increasing of both freeze-thaw cycle and strain rate. The relations among the fractal dimension, strain rates and freeze-thawing cycles are developed.

Molecular dynamics simulations of the coupled effects of strain and temperature on displacement cascades in α-zirconium

  • Sahi, Qurat-ul-ain;Kim, Yong-Soo
    • Nuclear Engineering and Technology
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    • v.50 no.6
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    • pp.907-914
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    • 2018
  • In this article, we conducted molecular dynamics simulations to investigate the effect of applied strain and temperature on irradiation-induced damage in alpha-zirconium. Cascade simulations were performed with primary knock-on atom energies ranging between 1 and 20 KeV, hydrostatic and uniaxial strain values ranging from -2% (compression) to 2% (tensile), and temperatures ranging from 100 to 1000 K. Results demonstrated that the number of defects increased when the displacement cascade proceeded under tensile uniaxial hydrostatic strain. In contrast, compressive strain states tended to decrease the defect production rate as compared with the reference no-strain condition. The proportions of vacancy and interstitial clustering increased by approximately 45% and 55% and 25% and 32% for 2% hydrostatic and uniaxial strain systems, respectively, as compared with the unstrained system, whereas both strain fields resulted in a 15-30% decrease in vacancy and interstitial clustering under compressive conditions. Tensile strains, specifically hydrostatic strain, tended to produce larger sized vacancy and interstitial clusters, whereas compressive strain systems did not significantly affect the size of defect clusters as compared with the reference no-strain condition. The influence of the strain system on radiation damage became more significant at lower temperatures because of less annealing than in higher temperature systems.

Analytical Algorithm Predicting Compressive Stress-Strain Relationship for Concrete Confined with Laminated Carbon Fiber Sheets

  • Lee, Sang-Ho;Kim, Hyo-Jin
    • Computational Structural Engineering : An International Journal
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    • v.1 no.1
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    • pp.39-48
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    • 2001
  • An analytical compressive stress-strain relationship model for circular and rectangular concrete specimens confined with laminated carbon fiber sheets (CFS) is studied. Tsai-Hill and Tsai-Wu failure criteria were used to implement orthotropic behavior of laminated composite materials. By using these criteria, an algorithm which analyzes the confinement effect of CFS on concrete was developed. The proposed analytical model was verified through the comparison with experimental data. Various parameters such as concrete strength, ply angle, laminate thickness, section shape, and ply stacking sequences were investigated. Numerical results by the proposed model effectively simulate the experimental compressive stress-strain behavior of CFS confined concrete specimens. Also, the pro-posed model estimates the compressive strength of the specimen to a high degree of accuracy.

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Dynamic Deformation Behavior of Aluminum Alloys Under High Strain Rate Compressive/Tensile Loading

  • Lee, Ouk-Sub;Kim, Guan-Hee;Kim, Myun-Soo;Hwang, Jai-Sug
    • Journal of Mechanical Science and Technology
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    • v.17 no.6
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    • pp.787-795
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    • 2003
  • Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as seismic loading are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar (SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, dynamic deformation behaviors of the aluminum alloys such as A12024-T4, A1606 IT-6 and A17075-T6 under both high strain rate compressive and tensile loading conditions are determined using the SHPB technique.