• Title/Summary/Keyword: High impact

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Evaluation of Impact Characteristics for High Strength Structural Steel at Low Temperature (고강도 구조용강의 저온 충격특성 평가)

  • 김재훈;김덕회;김후식;조성석;전병완;심인옥
    • Journal of the Korean Society of Propulsion Engineers
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    • v.5 no.3
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    • pp.1-9
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    • 2001
  • Impact tests are performed on the high strength structural steel that is being developed for the submarine material. Especially, the impact characteristics of this structural steels at low temperatures are investigated by charpy impact testing. Hyperbolic tangent curve fitting method is used to evaluate the LSE(lower shelf energy), USE(upper shelf energy) and DBTT(ductile-brittle transition temperature). Proportional equations between charpy impact energy and lateral expansion are obtained using the test results. Effect of temperature on the fracture appearance is investigated by using SEM.

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Evaluation of Impact Resistance Performance of High Strength Concrete by Projectile Size and Compressive Strength (압축강도 및 비상체의 크기에 따른 고강도 콘크리트의 내충격 성능평가)

  • Kim, Hong-Sub;Kim, Gyu-Yong;Miyauchi, Hiroyukui;Nam, Jeong-Soo;Jeon, Young-Seok;Koo, Kyoung-Mo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.05a
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    • pp.7-10
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    • 2011
  • In this study, evaluation system of impact resistance performance is proposed. Compressive strength of concrete is 40, 60 and 80MPa. It evaluate impact resistance performance to use projectile 6, 7 and 8mm size. As a result, safety performance is more higher when the compressive strength is increased in. Compared with Hughes's formula, evaluation system of impact resistance performance is appropriated.

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Module level EMC verification method for replacement items in nuclear power plant

  • Hee-Taek Lim;Moon-Gi Min;Hyun-Ki Kim;Gwang-Hyun Lee;Chae-Hyun Yang
    • Nuclear Engineering and Technology
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    • v.55 no.7
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    • pp.2407-2418
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    • 2023
  • Internal replaceable electronic module substitutions can impact EMC (ElectroMagnetic Compatibility) qualification testing and results if EMC testing is conducted at the cabinet level. The impact of component substitutions on EMC qualification results therefore should be evaluated. If a qualitative evaluation is not adequate to ensure that the modified product will not impact the cabinet level EMC qualification results, a new qualification testing should be conducted. Component level retesting should be conducted under electromagnetically equivalent conditions with the cabinet level test. This paper analyzes the propagation of conducted susceptibility test waveforms in a representative cabinet and evaluates the impact of component substitutions on cabinet level EMC qualification results according to the location of the replacement items. A guideline for a qualitative evaluation of the impact of component substitutions is described based on the propagation of the conducted susceptibility test waveforms. A module level test method is also described based on an analysis of the shielding effectiveness of the cabinet.

Prediction of Impact Energy Absorption in a High Weight Drop Tester by Response Surface Methodology (반응표면법을 사용한 고 중량물 낙하시험기의 충격에너지 흡수량 예측 연구)

  • Kang, Hoon;Jang, Jin-Seok;Kim, Da-Hye;Kang, Ji-Heon;Yoo, Wan-Seok;Lee, Jae-Wook
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.15 no.3
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    • pp.44-51
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    • 2016
  • This paper presents the characteristics of the energy absorption in an expansion tube type impact absorber that is applied to a high weight drop tester and the use of a response surface methodology to predict the impact energy absorption. In order to identify the characteristics of the energy absorption, a set of finite element analysis was conducted with Abaqus Explicit. Moreover, the ISCD-II sampling method and a first order polynomial were used to build a response surface. As a result, we demonstrated that the impact energy could be controlled by four main design variables, namely an expansion pipe's thickness, inner radius, pressing die's expansion angle and expansion ratio. Additionally, we observed the relationship between the four main design variables and the impact energy absorbing time, displacement, and maximum impact force.

Environmental Impact Assessment of the Carbody of a Electric Motor Unit(EMU) Using Simplified Life Cycle Assessment(S-LCA) (간략화 전과정 평가(S-LCA) 기법을 이용한 전동차 구체의 환경성 평가)

  • Lee Jae-Young;Mok Jai-Kyun;Jeong In-Tae;Kim Yong-Ki
    • Journal of the Korean Society for Railway
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    • v.8 no.6 s.31
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    • pp.520-524
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    • 2005
  • It is consequential to reduce the environmental impact of a product for sustainable development in 21st Century. In the field of transportation, especially, the technological market concerned about reduction and assessment of greenhouse gas emission is expected to be extended. The LCA gas been esteemed and utilized as a realistic alternative greenhouse gas emission is expected to be extended. The LCA has been esteemed and utilized as a realistic alternative to improve the environment by the assessment of environmental impacts. In this study, simplified life cycle assessment(S-LCA), was performed to analyze the environmental impacts quantitatively, which were produced through the life cycle of a electric motor unit(EMU). The object of the present work is rth investigate main parameters of environmental impacts and to establish the plans to improve the environment impact of EMU. As a result of quantitative assessment for environmental impact and manufacturing, the EMU carbody made of SUS showed acidification(AD) and marine water aquatic ecotoxicity(MAET) the most, while that made of Mild showed high impact of global warning(GW) and abiotic resources depletion(ARD). For the SUS EMU, the high AD and MAET impact is occurred by the discharged pollutants during acid-washing process. Also, high value of GW and ARD for Mild EMU is resulted from the consumption of iron ore, coal and crude oil during manufacturing. Therefore, the environment impact of carbody would be decreased by enhancing of energy efficiency and the lightening the weight of it.

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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Experimental Study on the Structural Safety of the Tractor Front-End Loader Against Impact Load

  • Park, Young-Jun;Shim, Sung-Bo;Nam, Ju-Seok
    • Journal of Biosystems Engineering
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    • v.41 no.3
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    • pp.153-160
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    • 2016
  • Purpose: This study was conducted to experimentally investigate the structural safety of and identify critical locations in a front-end loader under impact loads. Methods: Impact and static tests were conducted on a commonly used front-end loader mounted on a tractor. In the impact test, the bucket of the front-end loader with maximum live load was raised to its maximum lift height and was allowed to free fall to a height of 500 mm above the ground where it was stopped abruptly. For the static test, the bucket with maximum live load was raised and held at the maximum lift height, median height, and a height of 500 mm from the ground. Strain gages were attached at twenty-three main locations on the front-end loader, and the maximum stresses and strains were measured during respective impact and static tests. Results: Stresses and strains at the same location on the loader were higher in the impact test than in the static test, for most of measurement locations. This indicated that the front-end loader was put under a severe environment during impact loading. The safety factors for stresses were higher than 1.0 at all locations during impact and static tests. Conclusions: Since the lowest safety factor was higher than 1.0, the front-end loader was considered as structurally safe under impact loads. However, caution must be exercised at the locations having relatively low safety factors because failure may occur at these locations under high impact loads. These important design locations were identified to be the bucket link elements and the connection elements between the tractor frame and front-end loader. A robust design is required for these elements because of their high failure probability caused by excessive impact stress.

Evaluation of Impact Sound Insulation Properties of Light-Framed Floor with Radiant Floor Heating System

  • Nam, Jin-Woo;Park, Joo-Saeng;Lee, Jun-Jae
    • Journal of the Korean Wood Science and Technology
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    • v.30 no.3
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    • pp.75-84
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    • 2002
  • In order to find out impact insulation properties, various types of current radiant floor heating systems and light-framed floors that are used in light-framed residential buildings were evaluated for two types of impact sources at the same time. Sound Pressure Level (SPL) was different from each impact sources for those spectrum patterns and peaks. In case of light-framed floor framework, the excitation position and the assumed effective vibrating area have effects on sound pressure level but it is not considerable, and Normalized SPL was reduced for each frequency by increasing the bending rigidity of joist. The mortar layer in the radiant heating system had relatively high density and high impedance, therefore, it distributed much of the impact power when it was excited, and reduced the Normalized SPL considerably. Nevertheless, Increasing a thickness of mortar layer had little influence on SPL. Ceiling components reduced the sound pressure level about 5~25 dB for each frequency. Namely, it had excellent sound insulation properties in a range from 200 to 4,000 Hz frequency for both heavy and lightweight impact sources. Also, there was a somewhat regular sound insulation pattern for each center frequency. The resilient channel reduced the SPL about 2~11 dB, irrelevant to impact source. Consequently, current radiant floor heating systems which were established in light-framed residential buildings have quite good impact sound insulation properties for both impact sources.

Detection of High-Velocity Impact Damage in Composite Laminates Using PVDF Sensor Signals (고분자 압전 필름 센서를 이용한 복합재 적층판의 고속 충격 손상 탐지)

  • Kim Jin-Won;Kim In-Gul
    • Composites Research
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    • v.18 no.6
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    • pp.26-33
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    • 2005
  • The mechanical properties of composite materials may severely degrade in the presence of damage. Especially, the high-velocity impact such as bird strike, a hailstorm, and a small piece of tire or stone during high taxing, can cause considerable damage to the structures and sub-system in spite of a very small mass. However, it is not easy to detect the damage in composite plates using a single technique or any conventional methods. In this paper, the PVDF(polyvinylidene fluoride) film sensors were used for monitoring high-velocity impact damage initiation and propagation in composite laminates. The WT(wavelet transform) and STFT(short time Fourier transform) are used to decompose the sensor signals. A ultrasonic C-scan and a digital microscope are also used to examine the extent of the damage in each case. This research shows how various sensing techniques, PVDF sensor in particular, can be used to characterize high-velocity impact damage in advanced composite.

The Absorbed Energy of Carbon/Epoxy Composite Laminates Subjected to High-velocity impact in Considering the Loss of Projectile Mass (고속충격을 받는 Carbon/Epoxy 복합재 적층판의 충격체 질량손실을 고려한 흡수에너지 예측)

  • Cho, Hyun-Jun;Kim, In-Gul;Lee, Seokje;Kim, Young-A;Woo, Kyeongsik
    • Composites Research
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    • v.26 no.6
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    • pp.349-354
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    • 2013
  • In this paper, we conducted high velocity impact test for Carbon/Epoxy composite laminates and proposed advanced method for predicting the absorbed energy of composite laminates. During high-velocity impact test, we discovered loss of projectile mass macroscopically using high speed camera, thus we calculated the absorbed energy of composite laminates by taking loss of projectile mass into account. We proposed a model for predicting the absorbed energy of composite laminates subjected to high-velocity impact, the absorbed energy was classified into static energy and dynamic energy. The static energy was calculated by the quasi-static perforation equation that is related to the fiber breakage and static elastic energy. The dynamic energy can be divided by the kinetic energy of deformed specimen and fragment mass. Finally, the predicted absorbed energy considering loss of projectile mass was compared with experimental results.