• 제목/요약/키워드: quasi-static

검색결과 915건 처리시간 0.024초

Experimental and numerical study on energy absorption of lattice-core sandwich beam

  • Taghipoor, Hossein;Noori, Mohammad Damghani
    • Steel and Composite Structures
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    • 제27권2호
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    • pp.135-147
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    • 2018
  • Quasi-static three-point bending tests on sandwich beams with expanded metal sheets as core were conducted. Relationships between the force and displacement at the mid-span of the sandwich beams were obtained from the experiments. Numerical simulations were carried out using ABAQUS/EXPLCIT and the results were thoroughly compared with the experimental results. A parametric analysis was performed using a Box-Behnken design (BBD) for the design of experiments (DOE) techniques and a finite element modeling. Then, the influence of the core layers number, size of the cell and, thickness of the substrates was investigated. The results showed that the increase in the size of the expanded metal cell in a reasonable range was required to improve the performance of the structure under bending collapse. It was found that core layers number and size of the cell was key factors governing the quasi-static response of the sandwich beams with lattice cores.

압전 벤더의 효과적인 모델링 기법 (An Effective Quasi-static Modeling of the Piezoelectric Benders)

  • 박종규;문원규
    • 대한기계학회논문집A
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    • 제28권2호
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    • pp.133-142
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    • 2004
  • In this article, the constitutive relations of three types of piezoelectric benders, which are a unimorph bender, a bimorph bender and a triple-layer bender, are derived based on the beam theory under the quasi-static equilibrium condition. The relation coefficients are described as the geometry and material properties of the benders. More general constitutive relations involving fixed-free, fixed-roll, and fixed-simply supported boundary conditions under the inconsistent length condition between the piezoelectric layer and the nonpiezoelectric one are discussed. The complicated constitutive relations can be easily calculated and checked by using the symbolic function in ‘Mathematica’. The relation coefficients for the benders are plotted in three dimensional graph using the developed program.

준정적 실험에 의한 중공원형 콘크리트 교각의 소성응답 연구 (Research of Plastic response by Quasi-Static Test for Circulr Hollow R.C. Bridge Pier)

  • 정영수
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 1999년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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    • pp.247-255
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    • 1999
  • Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers circular hollow columns are widely used in Korean highway bridges Since the occurrence of 1995 Kobe earthquake there have been much concern about seismic design for various infrastructures inclusive of bridge structures. It is however understood that there are not much research works for nonlinear behavior circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is to investigate nonlinear behavior of hollow reinforced concrete bridge piers under the quasi-static cyclic load test and than to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It can be concluded from Quasi-static test for 7 bridge piers that approximate 4-5 ductility factor can be experimentally obtained for bridge piers nonseismically designed in conventional way which approximate 5-6 ductility factor for those seismically designed.

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Wind load combinations and extreme pressure distributions on low-rise buildings

  • Tamura, Yukio;Kikuchi, Hirotoshi;Hibi, Kazuki
    • Wind and Structures
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    • 제3권4호
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    • pp.279-289
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    • 2000
  • The main purpose of this paper is to demonstrate the necessity of considering wind load combinations even for low-rise buildings. It first discusses the overall quasi-static wind load effects and their combinations to be considered in structural design of low-rise buildings. It was found that the maximum torsional moment closely correlates with the maximum along-wind base shear. It was also found that the instantaneous pressure distribution causing the maximum along-wind base shear was quite similar to that causing the maximum torsional moment, and that this asymmetric pressure pattern simultaneously accompanies considerable across-wind and torsional components. Secondly, the actual wind pressure distributions causing maximum quasi-static internal forces in the structural frames are conditionally sampled and their typical pressure patterns are presented.

Cyclic behavior of interior beam-column connections in non-seismic RC frames at different loading rates

  • Dhakal, Rajesh P.;Pan, Tso-Chien
    • Structural Engineering and Mechanics
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    • 제23권2호
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    • pp.129-145
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    • 2006
  • This paper provides an insight into the response of non-seismic reinforced concrete (RC) building frames to excitations of different frequencies through experimental investigation. The results of cyclic loading tests of six full-scale RC beam-column sub-assemblies are presented. The tested specimens did not have any transverse reinforcement inside the joint core, and they were subjected to quasi-static and dynamic loading with frequencies as high as 20 Hz. Some important differences between the cyclic responses of non-seismic and ductile RC frames are highlighted. The effect of excitation frequency on the behavior of non-seismic joints is also discussed. In the quasi-static tests, shear deformation of the joint panel accounted for more than 50% of the applied story drift. The test results also showed that higher-frequency excitations are less detrimental than quasi-static cyclic loads, and non-seismic frames can withstand a higher load and a larger deformation when they are applied faster.

승강장 스크린 도어(PSD)시스템의 구조 안정성 평가 (Evaluation of the Structural Stability of Platform Screen Door(PSD))

  • 이재열;류봉조;전재선;김동현;이은규;신광복
    • 한국철도학회:학술대회논문집
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    • 한국철도학회 2006년도 추계학술대회 논문집
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    • pp.1190-1197
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    • 2006
  • We have evaluated the structural stability of a platform screen door due to train wind pressure. The platform screen door was installed at the ground and underground station and had 65 meters in length. Also, the platform screen door was a safety device because it was placed between the train and the platform. The finite element analysis was used to calculate the stresses and deflections of platform screen door caused by wind pressure using ANSYS 10.0. Quasi-static analysis was introduced to save calculating time and check quickly structural performances when compared to those of transient analysis. The results show that structural stability of the platform screen door under train wind pressure is proven and quasi-static analysis can quickly check the structural integrity of platform screen door.

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Analysis of behavior of bare and in-filled RC frames subjected to quasi static loading

  • Sandhu, Balvir;Sharma, Shruti;Kwatra, Naveen
    • Structural Engineering and Mechanics
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    • 제73권4호
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    • pp.381-395
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    • 2020
  • Study on the inelastic response of bare and masonry infilled Reinforced Concrete (RC) frames repaired using Carbon Fibre Reinforced Polymers (CFRP) and Glass Fiber Reinforced Polymers (GFRP) subjected to quasi- static loading is presented in the work. The hysteresis behaviour, stiffness retention, energy dissipation and damage index are the parameters employed to analyze the efficacy of FRP strengthening of bare and brick in-filled RC frames. It is observed that there is a significant improvement in load carrying capacity of brick infilled frame over bare RC frame. Also FRP strengthened brick infilled frame performs much better than FRP repaired bare frame under quasi static loading. Repair and retrofitting of brick infilled RC frame shows an improved load carrying and damage tolerance capacity than control frame.

달착륙선 충격흡수장치용 알루미늄 허니콤의 Crush Strength에 관한 연구 (Study of Crush Strength of Aluminum Honeycomb for Shock Absorber of Lunar Lander)

  • 김신;이혁희;김현덕;박정선;임재혁;황도순
    • 항공우주시스템공학회지
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    • 제4권3호
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    • pp.1-5
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    • 2010
  • Understanding the crushing behaviour of aluminum honeycombs under dynamic loading is useful for crash simulations of vehicles and for design of impacting energy absorbers. In the study of honeycomb crushing under quasi-static, dynamic loading, the most important parameter is crush strength. Crush strength is indicated to energy absorption characteristic of aluminum honeycomb. In this study, Using Finite Element Analysis carried out crush strength of hexagonal aluminum honeycomb then the results was compared with Quasi-static test. Consequently, Crush strength is different in quasi-static loading and dynamic loading about 16%.

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Study of the effect of varying shapes of holes in energy absorption characteristics on aluminium circular windowed tubes under quasi-static loading

  • Baaskaran, N;Ponappa, K;Shankar, S
    • Structural Engineering and Mechanics
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    • 제70권2호
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    • pp.153-168
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    • 2019
  • In this paper, energy absorption characteristics of circular windowed tubes with different section shapes (circular, ellipse, square, hexagon, polygon and pentagon) are investigated numerically and experimentally. The tube possesses the same material, thickness, height, volume and average cross sectional area which are subjected under axial and oblique quasi-static loading conditions. Numerical model was constructed with FE code ABAQUS/Explicit, the obtained outcome of simulation is in good matching with the experimental data. The energy absorbed, specific energy absorption, crash force efficiency, peak and mean loads along with the collapse modes with their initiation point of simple and windowed tubes were evaluated. The technique for order of preference by similarity ideal solution (TOPSIS) approach was employed for assessing their overall crushing performances. The obtained results confirm that efficacy of crash force indicators have improved by introducing windows and tubes with pentagonal and circular windows achieves the maximum ranking about 0.528 and 0.517, it clearly reveals the above are best window shapes.

고속 성형의 성형성 향상 입증을 위한 실험 및 이론적 성형한계선도 획득 및 비교 (Comparison of Forming Limit Diagram to Prove Improved Formability of High-speed Forming Acquired Experimentally and Theoretically)

  • 김민석;장윤호;김정
    • 소성∙가공
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    • 제33권2호
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    • pp.87-95
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    • 2024
  • The current study aims to prove that high-speed forming has better formability than conventional low-speed forming. Experimentally, the quasi-static forming limit diagram was obtained by Nakajima test, and the dynamic forming limit diagram was measured by electrohydraulic forming. For the experiments, the LS-DYNA was used to create the optimal specimen for electrohydraulic forming. The strain measurement was performed using the ARGUS, and comparison of the forming limit diagrams confirmed that EHF showed better formability than quasi-static forming. Theoretically, the Marciniak-Kuczynski model was used to calculate the theoretical forming limit. Swift hardening function and Cowper Symonds model were applied to predict the forming limits in quasi-static and dynamic status numerically.