• Title/Summary/Keyword: drop-weight impact test

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Weight Drop Impact Tests of Earthquake-Proof Table (내진테이블의 중량물 낙하 충격실험)

  • Eom, Tae Sung;Huh, Seok Jae;Park, Tae Won;Lee, Sang Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.22 no.7
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    • pp.369-378
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    • 2018
  • Full-scale seismic retrofit of old and deteriorated masonry buildings requires a lot of cost and time. In such buildings, installing an emergency evacuation space can be considered as an alternative. In this study, requirements of the earthquake-proof table used as an emergency evacuation space for buildings hit by earthquake are investigated. Load conditions required for the table, including the impact effects due to building debris drop, are explained. To investigate the impact effects in more detail, weight drop test is performed for an prototype earthquake-proof table. In the test, the weight of the falling object and free fall height were considered as the main test parameters. The results showed that the duration of impact is very short (0.0226~0.0779sec), and thus the impact forces increase to 15.8~45.2 times the weight of the falling object. Based on these results, design considerations and performance verification criteria of the earthquake-proof table as an emergency evacuation space are given.

Low-velocity Impact Behavior of Aluminum Honeycomb Sandwich Panel (알루미늄 하니컴 샌드위치 판넬의 저속충격거동)

  • 이현석;배성인;함경춘;한경섭;송정일
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2001.05a
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    • pp.78-82
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    • 2001
  • Impact behaviors of Aluminum Honeycombs Sandwich Panel(AHSP) by drop weight test were investigated. Two types of specimens with 1/2" and 1/4" cell size were tested by two impactors which are weight of $5.25\textrm{kg}_{\textrm{f}}$ and $11.9\textrm{kg}_{\textrm{f}}$. Parametric studies were achieved including the impactor weight and impact sites which consist face, long-edge, short-edge, and point of the specimen. Face one of impact sites was the strongest and short-edge one of impact sites was the weakest. The damaged area of AHSP was enlarged with the increase of impactor weight that is equal to impact energy. After 3 point bending test, fracture modes of AHSP were analyzed with AE counts. Lower facesheet was fractured in the long-edge direction and then separated between facesheet and core. In the short-edge direction after core wrinkled, lower facesheet tear occurred. Impact behavior by FE analysis were increased localized damage in fast velocity because the faster velocity of the impact was, the smaller the stress of core was. Consequently, impactor weight had an effect on widely damaged area, while the impact velocity was caused on the localized damaged area.aged area.

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A Study on the Strength Assessment of CFRP Laminate Plates by Drop-Weight Impact Test (낙추식 충격시험에 의한 CFRP 적층판의 강도평가에 관한 연구)

  • 이정주;박노식;양인영
    • Journal of the Korean Society of Safety
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    • v.14 no.3
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    • pp.12-17
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    • 1999
  • In this study, a drop-weight impact tester was manufactured to assess the strength of CFRP laminate plates. The tests were conducted on several laminates of different ply orientation. A system for the impact strength of CFRP laminates was made considering stress wave propagation theory using drop-weight impact tester as one of impact test. Results indicate that absorbed energy of quasi-isotropic specimen, haying four interfaces is higher than that of orthotropic laminates with two interfaces. Absorbed energy in the specimen that ply number, interface number and fiber stacking sequences is same but having hybrid is higher than that of orthotropic laminates without hybrid.

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A Study on the shape deformation of ball projectile(5.56mm) under the low velocity impact (저속충격시 Ball 탄(5.56mm)의 형상변화에 관한 연구)

  • 손세원;이두성;홍성희;김영태
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2002.05a
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    • pp.865-868
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    • 2002
  • This study investigated the shape deformation of ball projectile(5.56mn) under the low energy impact by the use of the drop weight impact tester. ball projectile(5.56mm) consisted of the copper face with a lead core. The impact conditions were changed with the variations of the mass and the drop height of the impact tup. Shape deformation of ball projectile(5.56mm) after low velocity impact was measured using a video microscope and CCD camera. The test result showed that impact energy by changing of drop height of the impact tup affected shape deformation of ball projectile(5.56mm). So, it is important to study the relativity between shape deformation of ball projectile(5.56mm) and ballistic protection of plate(such as hybrid composite laminates) under the high velocity impact.

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Influence of laminated orientation on the mechanical and thermal characteristics of carbon-fiber reinforced plastics

  • Shin, Hee-Jae;Kwac, Lee-Ku;Lee, Min-Sang;Kim, Hong-Gun
    • Carbon letters
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    • v.16 no.4
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    • pp.241-246
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    • 2015
  • Rapid industrial development in recent times has increased the demand for light-weight materials with high strength and structural integrity. In this context, carbon fiber-reinforced plastic (CFRP) composite materials are being extensively used. However, laminated CFRPs develop faults during impact because CFRPs are composed of mixed carbon fiber and epoxy. Moreover, their fracturing behavior is very complicated and difficult to interpret. In this paper, the effect of the direction of lamination in CFRP on the absorbed impact energy and impact strength were evaluated, including symmetric ply (0°/0°, −15°/+15°, −30°/+30°, −45°/+45°, and −90°/+90°) and asymmetric ply (0°/15°, 0°/30°, 0°/45°, and 0°/90°), through drop-weight impact tests. Further, the thermal properties of the specimens were measured using an infrared camera. Correlations between the absorbed impact energy, impact strength, and thermal properties as determined by the drop-weight impact tests were analyzed. These analyses revealed that the absorbed impact energy of the specimens with asymmetric laminated angles was greater than that of the specimens with symmetric laminated angles. In addition, the asymmetry ply absorbed more impact energy than the symmetric ply. Finally, the absorbed impact energy was inversely proportional to the thermal characteristics of the specimens.

Impact Fracture Behavior of Toughened Epoxy Resin Applied Carbon Fiber Reinforced Composites (Toughened 에폭시 수지를 사용한 탄소 섬유강화 복합재료의 충격파괴 거동)

  • 이정훈;황승철;김민영;김원호;황병선
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2003.10a
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    • pp.111-114
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    • 2003
  • Thermosets are highly cross-linked polymers with a three-dimensional molecular structure. The network structure gives rise to mechanical properties, however, one major drawback of thermosets, which also results from their network structure, is their poor resistance to impact and to crack initiation. In this study, to solve this problem, the reactive thermoplastics such as amine terminated polyetherimide (ATPEI), ATPEI-CTBN-ATPEI(ABA) triblock copolymer, CTBN-ATPEI(AB) diblock copolymer, and carboxyl group modified ATPEI was synthesized, after that blended with epoxy resin, and the carbon fiber reinforced composites were fabricated. The impact load, energy, and delamination were investigated by using drop weight impact test and C-scan test. As a results, the ABA/epoxy blend system showed good impact properties.

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An Experimental Study on Low-Velocity Impact Test and Response of Composite Laminates (복합적층판의 저속충격시험 및 거동에 대한 실험적 연구)

  • 최익현;홍창선
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.2
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    • pp.359-371
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    • 1994
  • A drop weight type impact test system is designed and set up to experimentally investigate impact responses of composite laminates subjected to the low-velocity impact. Using the test system, the impact velocity and the rebound velocity of the impactor as well as the impact force history are measured. An error of the measured data due to a difference in measuring position of the sensor is corrected and, for the estimation of real contact force history, a method of correcting an error due to friction forces is developed. Experimental methods to fix the boundary edgy of laminate specimens in impact testing are investigated and the impact tests on the specimens fixed by those methods are performed. Impact force histories and dynamic strains measured from the tests are compared with numerical results from the finite element analysis using the contact law. Consequently, the nonlinear numerical results considering the large deflection effects are agreed with the experimental results better than the linear ones.

The Evaluation of Shock Absorption Performance of Magneto-Rheological Elastomer Through the Drop Impact Test (낙하 충격 실험을 통한 자기유변탄성체의 충격 흡수 성능 평가)

  • Joeng, Kyeong Sik;Lee, Chul Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.10a
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    • pp.92-93
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    • 2013
  • In this study, Shock Absorption performance of Magneto-rheological elastomer(MRE) is identified through the drop impact test. Magneto-rheological materials are divided into two groups by MR fluid in fluid state and MR elastomer in solid state like rubber. The stiffness characteristics of Magneto-rheological material can be changed as magnetic field is applied. The impact loads in MR elastomer were measured under weight of impactor. Experiment results are shown through the experiments to confirm the effect of shock absorption of MR elastomer. Thus, the MR elastomer can be applied to shock absorber used in area that shock occurs.

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The Impact fracture Behaviors of Low Density LD Carbon/Carbon Composites by Drop Weight Impact Test (낙하 충격 시험에 의한 저밀도 2-D탄소/탄소 복합재의 충격파괴거동)

  • 주혁종;손종석
    • Polymer(Korea)
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    • v.26 no.2
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    • pp.270-278
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    • 2002
  • In this study, the fracture behavior by low velocity impact damage and the tendencies of impact energy absorption were investigated. Low velocity impact tests were performed using a mini tower drop weight impact tester, and graphite powder, carbon black and milled carton fiber were chosen as additives. Addition of graphite powder increased the maximum load and maintained the stress long until the total penetration happened. At the content of 9 vol%, they showed the maximum of 42% improvement in impact strength compared composites containing no additives. At the test with low impact energy of 0.4 J, impact energy was consumed by delamination in the composite containing no additives, however, as graphite contents increased, the tendency of failure changed to the penetration of the specimen.

Influence of Fiber Strength and Stacking Sequences on Impact Damages of CFRP Composites (섬유강도와 적층구성이 CFRP적층판의 충격손상에 미치는 영향)

  • 임광희;박노식;양인영
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.3
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    • pp.210-220
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    • 2001
  • This paper aims at the evaluation on the characterization of CFRP laminate plates using falling weight impact tester. The experimentation was conducted on several laminates of different fiber and ply orientation. A system was built for the impact strength of CFRP laminates in consideration of stress wave propagation with using drop-weight impact tester as one of impact test. Absorbed energy of orthotropic composites with using T300 fiber, which are composed of the same fiber and stacking number is higher than that or quasi-isotropic specimen over impact energy 7J, but in case or using T700 fiber, much difference does not show. Also, absorbed energy of orthotropic composites with using T300 fiber, which are composed or stacking number and orientation became more than that of T700 fiber specimen; however great change doesn't show in case of quasi-isotropic specimens. It is found that influence was confirmed between impact energy and absorbed energy as the impact energy is increased with adding the falling weight.

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