• Title, Summary, Keyword: 준 정적 실험

Search Result 138, Processing Time 0.042 seconds

Prediction of Ballistic Limit for Composite Laminates Subjected to High-velocity Impact Using Static Perforation Test (정적압입 관통 실험을 이용한 복합재 적층판의 고속충격 탄도한계속도 예측)

  • You, Won-Young;Kim, In-Gul;Lee, Seokje;Kim, Jong-Heon
    • Composites Research
    • /
    • v.26 no.1
    • /
    • pp.21-28
    • /
    • 2013
  • The ballistic limit of Carbon/Epoxy composite laminates with the finite effective area are predicted by using the quasi-static perforation test and semi-empirical formula. The perforation energy were calculated from force-displacement curve in quasi-static perforation test. Also, the actual ballistic limit and penetration energy were obtained through the high-velocity impact test. The quasi-static perforation test and high-velocity impact test were conducted for the specimens with 3 different effective areas. In the high-velocity impact test, the air gun impact tester were used, and the ballistic and residual velocity was measured. The required inputs for the semi-empirical formula were determined by the quasi-static perforation tests and high-velocity impact tests. The comparison between semi-empirical formula and high-velocity impact test results were conducted and examined. The ballistic limits predicted by semi-empirical formula were agreed well with high-velocity impact test results.

금속 성형 공정의 준정적 변형 예측을 위한 외연적 시간 적분 유한 요소법의 적용성 연구

  • 유요한;양동열
    • Proceedings of the Korean Society of Precision Engineering Conference
    • /
    • /
    • pp.192-197
    • /
    • 1995
  • 소재의 손실을 최소한 줄이면서 원하는 형상의 제품을 가공하는 가장 기본적인 금속 가공 방법은 금형을 이용하는 금속 성형(metal forming)이다. 본 논문에서는 준정적 금속 성형 문제 해석 에대한 외연적 시간 적분 유한 요소법의 적용성을 평가 하기 위하여 변형모드가 복잡한 박판튜브 (thin-walled tube)의 좌굴문제를 해석하여 변형과정이 이론 및 실험결과와 비교적 잘 일치하는지 살펴보기로 한다. 또한 준정적 금속 성형 문제 해석에 외연적 시간 적분 유한 요소법을 사용할 때 계산 시간을 줄이기 위하여 많이 사용되는 가압속도 조절법(loading velocity control technique) 의 타당성을 평가하기 위하여 박판 튜브와 중실 실린더(solid cylinder)의 변형 속도에 따른 변형 모드의 변화를 비교 관찰하여 기하학적 형상에따른 가압속도 조절법의 적용 가능 여부를 분석하여 보겠다.

  • PDF

Study on Reinforcement Effect of Circular RC Columns by Helical Bar Under Cyclic Lateral Load (반복 횡하중을 받는 원형 철근콘크리트 기둥의 Helical Bar 보강효과에 대한 연구)

  • Kim, Seong-Kyum;Park, Jong-Kwon;Han, Sang-Hee;Kim, Byung-Cheol;Jang, Il-Young
    • Journal of the Korea institute for structural maintenance and inspection
    • /
    • v.18 no.1
    • /
    • pp.48-58
    • /
    • 2014
  • In this study, quasi-static according to the displacement-controlled (strain control) method tests on RC columns for seismic reinforcement performance in accordance with the provisions of the seismic design and construction before 1992 design code for highway bridges in korea. Used reinforcement that improves the performance of Inorganic Helical Bar, a kind of alloy steel, circular columns were tested outside the seismic reinforcing. In the experiment, fracture behavior, lateral load-displacement relation, ductility and energy assessment evaluation was performed through tests. The variables in experimental are section force of reinforcement, spiral reinforcement spacing, reinforcement method. Improved seismic performance and effect were confirmed through quasi-static test experiments. The results of study confirmed determination the appropriate size of reinforcement, reinforcement forces, spacing and selection of the type required, furthermore, not only mechanical reinforcement but also substitution of high-strength concrete reinforced with concrete cover improved seismic performance.

The Experimental Study on the Absorbed Energy of Carbon/Epoxy Composite Laminated Panel Subjected to High-velocity Impact (고속 충격을 받는 Carbon/Epoxy 복합재 적층판의 흡수 에너지 예측에 대한 실험적 고찰)

  • Cho, Hyun-Jun;Kim, In-Gul;Lee, Seokje;Woo, Kyeongsik;Kim, Jong-Heon
    • Composites Research
    • /
    • v.26 no.3
    • /
    • pp.175-181
    • /
    • 2013
  • The evaluation and prediction for the absorbed energy, residual velocity, and impact damage are the key things to characterize the impact behavior of composite laminated panel subjected to high-velocity impact. In this paper, the method to predict the residual velocity and the absorbed energy of Carbon/Epoxy laminated panel subjected to high velocity impact are proposed and examined by using quasi-static perforation test and high-velocity impact test. Total absorbed energy of specimen due to the high-velocity impact can be grouped with static energy and kinetic energy. The static energy are consisted of energy due to the failure of the fiber and matrix and static elastic energy, which are related to the quasi-static perforation energy. The kinetic energy are consisted of kinetic energy of moving part of specimen, which are modelled by three modified kinetic model. The high-velocity impact test were conducted by using air gun impact facility and compared with the predicted values. The damage area of specimen were examined by C-scan image. In the high initial impact velocity above the ballistic limit, both the static energy and the kinetic energy are known to be the major contribution of the total absorbed energy.

Capacity Evaluation of Joint Reinforcement with Debonding Area at the Interface Steel to Concrete Surface (접합부 철근의 비부착에 따른 성능평가)

  • Jung, Woo-Young;Ha, Keum-Hee
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • /
    • pp.67-70
    • /
    • 2011
  • 해안에 위치한 철근콘크리트 구조물 및 사회 간접 시설물들은 염해피해에 대한 우려가 있다. 염해피해로 인한 철근의 부식현상이 발생하면 철근과 콘크리트 부착성능의 저하로 인한 부재의 내력감소를 가져 올 수 있다. 따라서 본 연구에서는 염해부식이 진행되어 콘크리트와 철근간의 부착 및 비부착 여부에 따른 성능을 확인하기 위하여 완전 비부착된 보-기둥 접합부를 철근부착용 고무튜브를 이용하여 제작하였다. 제작된 실험체로 준정적 반복횡하중을 이용한 실험을 통해 성능평가를 수행하였다. 비부착된 보-기둥 접합부의 비선형 해석을 하기 위해 4절점 래티스 모델로 개선하여 적용하였다.

  • PDF

Seismic Performance Assessment of Reinforced Concrete Bridge Columns with Interlocking Circular Hoops (결합원형띠철근을 갖는 철근콘크리트 교각의 내진성능평가)

  • Kim, Tae-Hoon;Park, Kwang-Soon;Kang, Hyeong-Taek
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.15 no.6
    • /
    • pp.81-90
    • /
    • 2011
  • The purpose of this study was to investigate the seismic performance of reinforced concrete bridge columns with interlocking circular hoops. Three interlocking columns were tested under a constant axial load and a quasistatic, cyclically reversed horizontal load. A computer program, RCAHEST (Reinforced Concrete Analysis in Higher Evaluation System Technology) was used for the analysis of reinforced concrete structures. The used numerical method gives a realistic prediction of performance throughout the loading cycles for several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve the existing practice in the design and construction of reinforced concrete bridge columns with interlocking circular hoops.

Seismic Performance Assessment of Hollow Circular Reinforced Concrete Bridge Columns with Confinement Steel (중공원형 철근콘크리트 교각의 횡방향철근에 따른 내진성능평가)

  • Kim, Tae-Hoon;Kang, Hyeong-Taek
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.16 no.1
    • /
    • pp.13-25
    • /
    • 2012
  • The purpose of this study was to investigate the seismic behavior of hollow circular reinforced concrete bridge columns with confinement steel, and to develop improved seismic design criteria. Three hollow circular columns were tested under a constant axial load and a quasi-static, cyclically reversed horizontal load. The accuracy and objectivity of the assessment process can be enhanced by using a sophisticated nonlinear finite element analysis program. The numerical method used gives a realistic prediction of the seismic performance throughout the loading cycles for the several test specimens investigated. Based on the experimental and analytical results, design recommendations are presented to improve current practice in the design and construction of hollow circular reinforced concrete bridge columns.

Centrifugal Test on Behavior of the Dolphin Structure under Ship Collision (선박충돌 시 돌핀 구조물의 거동에 대한 원심모형실험)

  • Oh, SeungTak;Bae, WooSeok;Cho, SungMin;Heo, Yol
    • Journal of the Korean Geoenvironmental Society
    • /
    • v.12 no.1
    • /
    • pp.61-70
    • /
    • 2011
  • The impact protection system consists of an arrangement of circular sheet pile cofferdams-denoted dolphin structuredeeply embedded in the seabed, filled with crushed rock and closed at the top with a robust concrete cap. Centrifuge model tests were performed to investigation the behaviors of dolphins in this study. Total 7 quasi-model tests and 11 dynamic model tests were performed. The main experimental results can be summarized as follows. Firstly, The experimental force-displacement results for quasi-static tests show a limited influence on the initial stiffness of the structure from the change in fill density and the related change in the stiffness of the fill. And by comparing the dissipation at the same dolphin displacement it was found that the denser fill increase the dissipation by 16% for the 20m dolphin and by 23% for the 30m dolphin. The larger sensitivity for the large dolphin is explained by a larger contribution to the dissipation from strain in the fill. In low level impacts the dynamic force-response is up to 26~58% larger than the quasi-static and the dissipation response is showed larger in small displacement. Hence, it is concluded conservative to use the quasi-static response characteristics in the approximation of the response, and it is further concluded that the dolphin resistance to low level impacts is demonstrated to be equivalent and even superior to the high level impacts.

Experimental Study for the Impact Characteristics of Expanded EPP/EPS Foams (발포 EPP/EPS의 충격특성에 관한 실험적 연구)

  • Kim, Han-Kook;Kim, Byeoung-Jun;Jeong, Kwang-Young;Cheon, Seong S.
    • Composites Research
    • /
    • v.26 no.6
    • /
    • pp.343-348
    • /
    • 2013
  • In the present study, quasi-static tests and impact tests were performed for investigating the mechanical behaviour of EPP (Expanded polypropylene) and EPS (Expanded polystyrene). Four different density cylindrical type specimens were prepared for EPP and EPS and 0.001 $s^{-1}$ and 0.1 $s^{-1}$ of strain rate conditions for quasi-static tests and 100 J, 200 J and 300 J of incident energy conditions for the instrumented impact tests were considered.

Seismic Performance Evaluation of Circular RC Bridge Piers with Shear-Flexure Behavior (휨-전단 복합 거동을 보이는 RC 원형교각의 내진성능 평가)

  • 김병석;김영진;곽임종;조창백;조정래
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.5 no.3
    • /
    • pp.29-36
    • /
    • 2001
  • Same as-built drawings in national roadway bridges in Korea were examined. As a result, many bridge piers were found whose aspect ratios are in the vicinity of 2.5. These columns are expected to do shear-flexure behaviour, but the previous research works considered flexure behaviour columns only. In the study, therefore, a shear-flexure behaviour column was selected as the model pier, and quasi static test on the full and 1/2 scale models was carried out. From the test results, the scale effect on the seismic performance evaluation was analyzed, and the seismic performance of the model bridge pier without seismic details was evaluated by the capacity spectrum method.

  • PDF