• Title, Summary, Keyword: quasi-static test

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Quasi-static Characteristics in Radial Direction of 100 kWh Class Superconductor Bearing (100 kWh급 초전도 베어링의 지름방향 준정적 특성)

  • Jung, S.Y.;Park, B.J.;Han, Y.H.;Park, B.C.;Lee, J.P.;Han, S.C.
    • Progress in Superconductivity
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    • v.12 no.1
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    • pp.27-31
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    • 2010
  • A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. Many aspects of the quasi-static behavior of flywheel rotors still need to be studied closely, and the rotors require a stable and highly efficient supporting system such as high temperature superconductor (HTS) bearings, which offer dynamic stability without the use of active control. Quasi-static properties of HTS bearings in the radial direction provide data to solve problems which may occur in a running system. Since stiffness in countering rotor vibration is the main parameter for designing an HTS bearing system, we investigated the quasi-static properties of the magnetic force between permanent magnets(PMs) and HTS bulks in the radial direction. We measured radial stiffness, and discovered that bearing stiffness varied greatly depending on the number of active HTS bulks. This is valuable data for predicting the change in stiffness during partial HTS bearing failure. The quasi-static test results are used for optimal design and performance prediction for the 100 kWh class superconductor bearing.

Experimental and Numerical Studies on Composite Tubes for the Energy Absorber of High-speed Train (복합재 튜브를 이용한 고속 열차의 에너지 흡수장치에 대한 실험 및 수치해석 연구)

  • Nguyen, Cao-Son;Jang, Hong-Kyu;Shin, Jae-Hwan;Son, Yu-Na;Kim, Chun-Gon
    • Composites Research
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    • v.24 no.1
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    • pp.1-9
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    • 2011
  • This paper presents an experimental and numerical study on composite tubes for the energy absorber of the high-speed train. The purpose of the experimental study is to find out which lay-up is the best lay-up for the energy absorber. Four lay-ups were tested using quasi static method: $[0/45/90/-45]_4$, $[0]_{16}$, $[0/90]_8$, $[0/30/-30]_5$. Two triggering methods were used to create initial damage and guarantee the progressive collapse mode: bevel edge and notch edge. As a result, $[0/45/90/-45]_4$ lay-up was find out the best lay-up among the laminates being tested. In the numerical study, a parametric analysis was done to find out the most proper way to simulate the quasi static test of a composite tube using LS-DYNA program. A single composite tube was modeled to be crashed by a moving wall. Comparison between simulation and experiment was done. Reasonable agreement between experiment and analysis was obtained. Dealing with parameter TFAIL and the mass scaling factor, this parametric study shows the ability and the limitation of LS-DYNA in modeling the quasi static test for the composite tube.

Quasi-Static and Dynamic Deformation Behavior of STS304- and Ta-fiber-reinforced Zr-based Amorphous Matrix Composites Fabricated by Liquid Pressing Process (액상가압공정으로 제조된 STS304와 Ta 섬유 강화 Zr계 비정질 복합재료의 준정적 및 동적 변형거동)

  • Kim, Yongjin;Shin, Sang Yong;Kim, Jin Sung;Huh, Hoon;Kim, Ki Jong;Lee, Sunghak
    • Korean Journal of Metals and Materials
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    • v.48 no.6
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    • pp.477-488
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    • 2010
  • Zr-based amorphous alloy matrix composites reinforced with stainless steel (STS) and tantalum continuous fibers were fabricated without pores or defects by a liquid pressing process, and their quasi-static and dynamic deformation behaviors were investigated by using a universal testing machine and a Split Hopkinson pressure bar, respectively. The quasi-static compressive test results indicated that the fiberreinforced composites showed amaximum strength of about 1050~1300 MPa, and its strength maintained over 700 MPa until reaching astrain of 40%. Under dynamic loading, the maximum stresses of the composites were considerably higher than those under quasi-static loading because of the strain-rate hardening effect, whereas the fracture strains were considerably lower than those under quasi-static loading because of the decreased resistance to fracture. The STS-fiber-reinforced composite showed a greater compressive strength and ductility under dynamic loading than the tantalum-fiber-reinforced composite because of the excellent resistance to fracture of STS fibers.

Collapse Characteristics of vehicle Members with Spot Welded Hat-Shaped Section under Axial Compression (점용접된 차체구조용 모자형 단면부재의 축방향 압궤특성)

  • 차천석;양인영;전형주;김용우;김정호
    • Journal of the Korean Society of Safety
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    • v.15 no.4
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    • pp.20-27
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    • 2000
  • The hat shaped section members, spot welded strength resisting structures are the most energy absorbing ones of automobile components during the front-end collision. Under the static axial collapse load in velocity of 10mm/min and quasi-static collapse load in velocity of 1000mm/min, the collapse characteristics of the hat shaped section and double hat shaped section member have been analyzed by axial collapse tests with respect to the variations of spot weld pitches on the flanges. In addition, the quasi-static collapse simulations have been implemented in the same condition to the experiment's using FEM package, LS-DYNA3D. The simulated results have been verified in comparison with these from the quasi-static axial collapse tests. With the computational approaches the optimal energy absorbing structures can be suggested. Simulations are so helpful that the optimized data be supplied in designing vehicles in advance.

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Quasi-Static Test for Seismic Performance of Reinforced Concrete Bridge Piers with Lap Splice (준정적실험에 의한 실물 원형교각의 내진성능평가를 위한 실험적 연구)

  • Kim, Hoon;Chung, Young-Soo;Lee, Jae-Hoon;Choi, Jin-Ho;Cho, Jun-Sang
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.941-946
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    • 2002
  • Short reinforced concrete bridge piers are particularly susceptible to shear failure as a consequence of the high shear/moment ratio and conservatism in the flexural strength design of existing RC bridge pier, which were constructed before 1992. In addition, shear failure is brittle and involves rapid strength degradation. Inelastic shear deformation is thus unsuitable for ductile seismic response. It is, however, believed that there are not many experimental research works for shear failure of the existing RC bridge pier in Korean peninsula subjected to earthquake motions. The object of this research is to evaluate the seismic performance of existing circular RC bridge piers by the quasi-static test. Existing RC bridge piers were moderate seismically designed in accordance with the conventional provisions of Korea Highway Design Specification. This study has been performed to verify the effect of aspect ratio (column height-diameter ratio). Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteric curve, envelope curve etc.

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Quasi-static test of the precast-concrete pile foundation for railway bridge construction

  • Zhang, Xiyin;Chen, Xingchong;Wang, Yi;Ding, Mingbo;Lu, Jinhua;Ma, Huajun
    • Advances in concrete construction
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    • v.10 no.1
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    • pp.49-59
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    • 2020
  • Precast concrete elements in accelerated bridge construction (ABC) extends from superstructure to substructure, precast pile foundation has proven a benefit for regions with fragile ecological environment and adverse geological condition. There is still a lack of knowledge of the seismic behavior and performance of the precast pile foundation. In this study, a 1/8 scaled model of precast pile foundation with elevated cap is fabricated for quasi-static test. The failure mechanism and responses of the precast pile-soil interaction system are analyzed. It is shown that damage occurs primarily in precast pile-soil interaction system and the bridge pier keeps elastic state because of its relatively large cross-section designed for railways. The vulnerable part of the precast pile with elevated cap is located at the embedded section, but no plastic hinge forms along the pile depth under cyclic loading. Hysteretic curves show no significant strength degradation but obvious stiffness degradation throughout the loading process. The energy dissipation capacity of the precast pile-soil interaction system is discussed by using index of the equivalent viscous damping ratio. It can be found that the energy dissipation capacity decreases with the increase of loading displacement due to the unyielding pile reinforcements and potential pile uplift. It is expected to promote the use of precast pile foundation in accelerated bridge construction (ABC) of railways designed in seismic regions.

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

  • Kim, Shin;Lee, Hyuk-Hee;Kim, Hyun-Duk;Park, Jung-Sun;Im, Jae-Hyuk;Hwang, Do-Soon
    • Journal of Aerospace System Engineering
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    • v.4 no.3
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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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Quasi-Static Tests on SRC Composite Columns (SRC 합성교각의 준정적 실험)

  • Shim, Chang-Su;Chung, Young-Soo;Jung, In-Keun;Min, Jin;Han, Jung-Hun
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.299-302
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    • 2005
  • This study deals with the quasi-static tests on steel reinforced concrete composite columns with single embedded steel or multiple members. For the design of bridge piers, the composite section needs to have low steel ratio for cost savings because the dimension of the pier section is usually large. There is lack of design guidelines for these composite columns with low steel ratio, but the design provisions for the normal reinforced concrete column can be used for the design because of the low steel ratio. It is necessary to provide the design provisions in terms of the strength limit state and seismic performance by the detail requirements on the longitudinal steel and the transverse steel. The test parameters in this study were determined considering the current design provisions on RC columns. Through the quasi-static tests, the seismic performance of the composite columns were discussed.

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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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    • v.23 no.2
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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.

Seismic Performance Evaluation of Circular RC Bridge Piers with Various Steel Type (원형 실물 철근 콘크리트 교각의 철근 상세에 따른 내진성능 평가)

  • 정영수;박진영;이재훈;조대연;이대형
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.965-970
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    • 2001
  • The object of this research is to evaluate the seismic performance of existing RC bridge piers that were constructed before the adoption of the seismic design provision of Korea Bridge Design Specification in 1992. In this research, adopted test parameters were limited ductile design or non-seismic design, aspect ratio, confinement steel type, loading pattern, lap-spliced ratio for longitudinal reinforcement. This study has been performed to verify the effect of test parameter by quasi-static test. Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as lateral force-displacement hysteretic curve, envelope curve etc. It has been observed that seismic performance of lap-spliced test specimen, non-seismically designed specimens, was significantly reduced.

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