• Title/Summary/Keyword: shock absorption performance

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Development for Shock Absorption System by Using FE Analysis (FE 해석을 통한 충격흡수시설의 개발)

  • Kang, Y.H.;Kim, H.J.;Park, D.H.;Kim, K.S.;Kang, B.S.
    • Proceedings of the KSME Conference
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    • 2000.04a
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    • pp.224-229
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    • 2000
  • This paper describe a (mite element computer simulation of a absorption system using full scale car crash test. The full scale test selected for this study is a 80kmh frontal, side and 25% offset impact of a 1993 Ford Taurus vehicle into a absorption system. This absorption system has external rubber and internal steel pannel. This simulation has completed for decision of these components energy absorption performance. Dynamical performance of this system and movement are obtained from this simulation. and then We can appreciate the safety of passenger from measure the vehicle C.G's acceleration.

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Structure and Technology of Personal Protection Helmets (인체보호용 헬멧의 구조 및 기술)

  • Hwang, Jae Hyung;Jeong, Won Young
    • Journal of the Korean Society of Clothing and Textiles
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    • v.41 no.4
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    • pp.771-781
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    • 2017
  • The helmet is an imperative personal protective equipment. This protective device must be able to guard the human head against potential risks. Helmets are classified according into the purpose of use; therefore, the required performance and specifications depend on the type of products. Military helmets are intended to protect the wearer's head from bullets and shrapnel. Generally, lightweight super fibers and fiber reinforced composite materials are used as helmet shell materials, and NIJ STD of U.S. Department of Justice is most widely used as international standard related to bulletproof helmets. Safety helmets are widely used for industrial application and sports leisure. In general, the performance of shock absorption must be ensured, and various lining systems are applied in material, design, and combination methods. Evaluation standards have also been classified and strictly controlled for each purpose; therefore, it is difficult to certify with the existing standards such as the recently developed convergence helmets. However, it is possible to launch the product through a separate national integrated certification procedure.

Tests on explosion-resisting properties of high-performance equal-sized-aggregate concrete composite sandwich plates

  • Yizhong Tan;Songlin Yue;Gan Li;Chao Li;Yihao Cheng;Wei Dai;Bo Zhang
    • Structural Engineering and Mechanics
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    • v.87 no.4
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    • pp.297-304
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    • 2023
  • Targeted introduction of explosion-resisting and energy-absorbing materials and optimization of explosion-resisting composite structural styles in underground engineering are the most important measures for modern engineering protection. They could also improve the survivability of underground engineering in wartime. In order to test explosion-resisting and energy-absorbing effects of high-performance equal-sized-aggregate (HPESA) concrete, the explosive loading tests were conducted on HPESA concrete composite plates by field simple explosion craters. Time-history curves of the explosion pressure at the interfaces were obtained under six conditions with different explosion ranges and different thicknesses of the HPESA concrete plate. Test results show that under the same explosion range, composite plate structures with different thicknesses of the HPESA concrete plate differ significantly in terms of the wave-absorbing ability. Under the three thicknesses in the tests, the wave-absorbing ability is enhanced with the growing thickness and the maximum pressure attenuation index reaches 83.4%. The energy attenuation coefficient of the HPESA concrete plate under different conditions was regressively fitted. The natural logarithm relations between the interlayer plate thickness and the energy attenuation coefficient under the two explosion ranges were attained.

Analysis of Vibration Suspension Device for Trailer in Agricultural Products (농산물 수송 트레일러의 현가장치 진동 분석)

  • Hong, Jong-Ho;Lee, Seong-Beom;Park, Won-Yeob;Kim, Seong-Yeob;Wu, Yong-Gun
    • Journal of Bio-Environment Control
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    • v.21 no.4
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    • pp.437-444
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    • 2012
  • This study was aimed to minimized the impact force and vibration transmitted to transporting agricultural product from the power tiller trailer by installing vibration absorption device. The vibration absorbable trailer (I) mounted with leaf spring suspension and shock absorber was developed and compared on vibration absorption performance with the existing trailer (E) equipped no vibration absorption device. In order to identify the vibration absorption effect of the trailer developed in this study, the vibration accelerations, occurred during driving on paved road with loading 360 kg of pear, were measured and analyzed using FFT analyzer. The magnitude of average vibration acceleration was decreased highly for the improved trailer mounted with vibration absorption device in comparing with existing trailer in the frequency range under 60 Hz and under 80 Hz. And similar vibration absorption effect was represented for the improved trailer in all frequency range. Especially, in the frequency range between 40 Hz and 80 Hz, the magnitude of vibration acceleration for the improved trailer was decreased with 1/3 times in comparing with existing trailer. So, the transporting loss including damage of agricultural product could be decreased highly by using the improved vibration absorbable trailer mounted with leaf spring suspension and shock absorber simultaneously, designed in this study.

Dynamic performance of girder bridges with explosion-proof and aseismic system

  • Wang, Jingyu;Yuan, Wancheng;Wu, Xun;Wei, Kai
    • Structural Engineering and Mechanics
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    • v.61 no.3
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    • pp.419-426
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    • 2017
  • Recently, the transportation of dangerous explosive goods is increasing, which makes vehicle blasting accidents a potential threat for the safety of bridge structures. In addition, blasting accidents happen more easily when earthquake occurs. Excessive dynamic response of bridges under extreme loads may cause local member damage, serviceability issues, or even failure of the whole structure. In this paper, a new explosion-proof and aseismic system is proposed including cable support damping bearing and steel-fiber reinforced concrete based on the existing researches. Then, considering one 40m-span simply supported concrete T-bridge as the prototype, through scale model test and numerical simulation, the dynamic response of the bridge under three conditions including only earthquake, only blast load and the combination of the two extreme loads is obtained and the applicability of this explosion-proof and aseismic system is explored. Results of the study show that this explosion-proof and aseismic system has good adaptability to seism and blast load at different level. The reducing vibration isolation efficiency of cable support damping bearing is pretty high. Increasing cables does not affect the good shock-absorption performance of the original bearing. The new system is good at shock absorption and displacement limitation. It works well in reducing the vertical dynamic response of beam body, and could limit the relative displacement between main girder and capping beam in different orientation so as to solve the problem of beam falling. The study also shows that the enhancement of steel fibers in concrete could significantly improve the blast resistance of main beam. Results of this paper can be used in the process of antiknock design, and provide strong theoretical basis for comprehensive protection and support of girder bridges.

Evaluation of Seismic Performance for RC Bridge Piers According to Longitudinal Steel Connection Method (철근 콘크리트 교각의 주철근 이음방법에 따른 내진성능 평가)

  • 박진영;정영수;박창규;김영섭;이대형
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.10a
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    • pp.323-328
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    • 2002
  • The 1995 devastating Hyogoken-Nambu earthquake sent mental shock waves that awakened the public concern about the seismic performance of infrastructures in Korea. Seismic safety of reinforced concrete bridge piers could be secured through sufficient strength and stiffness of longitudinal steels and confined core concrete, and through ductile behaviour of bridge piers in the inelastic range. This study has been performed to verify the effect of lap spliced longitudinal steel for the seismic behavior of reinforced concrete bridge piers. Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as displacement ductility, energy absorption etc.

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Dynamic tensile behavior of SIFRCCs at high strain rates

  • Kim, Seungwon;Park, Cheolwoo;Kim, Dong Joo
    • Computers and Concrete
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    • v.26 no.3
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    • pp.275-283
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    • 2020
  • Reinforced concrete (RC) does not provide sufficient resistance against impacts and blast loads, and the brittle structure of RC fails to protect against fractures due to the lack of shock absorption. Investigations on improving its resistance against explosion and impact have been actively conducted on high-performance fiber-reinforced cementitious composites (HPFRCCs), such as fiber-reinforced concrete and ultra-high-performance concrete. For these HPFRCCs, however, tensile strength and toughness are still significantly lower compared to compressive strength due to their limited fiber volume fraction. Therefore, in this study, the tensile behavior of slurry-infiltrated fiber-reinforced cementitious composites (SIFRCCs), which can accommodate a large number of steel fibers, was analyzed under static and dynamic loading to improve the shortcomings of RC and to enhance its explosion and impact resistance. The fiber volume fractions of SIFRCCs were set to 4%, 5%, and 6%, and three strain rate levels (maximum strain rate: 250 s-1) were applied. As a result, the tensile strength exceeded 15 MPa under static load, and the dynamic tensile strength reached a maximum of 40 MPa. In addition, tensile characteristics, such as tensile strength, deformation capacity, and energy absorption capacity, were improved as the fiber volume fraction and strain rate increased.

A Study on the Safety Performance of the Air Chamber TMA through Accident Analysis (사고분석을 통한 에어챔버 트럭충격흡수장치의 안전성능에 대한 연구)

  • Jo, Huichang;Park, Insong
    • Transactions of the Korean Society of Automotive Engineers
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    • v.24 no.3
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    • pp.352-357
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    • 2016
  • More recently, workers and passengers of casualties has increased by rear-end collisions of unexpected while working on the road. Recently attracted air chamber TMA mounting car accidents which occurred in 3 years, and analyzed the effect of reducing the shock absorption and protection performance and casualties. There is a risk of the vehicle AIS4 more injury of high five accidents of casualties risk, also, was the analysis that there is risk of death was avoided by the air chamber TMA and SGT. Therefore, by mounting the TMA in the rear-end accident, so you can reduce the death and casualties, it must be increased this of attach rate for road construction vehicle.

Comparison of Heel-rocking Time Between Young Women and Elderly Women (젊은 여성과 고령자 여성의 힐락킹 시간 비교 분석)

  • Yun, Ju-seok;Kim, Ji-Won;Kwon, Yu-Ri;Heo, Jae-Hoon;Jeon, Hyeong-Min;Jeon, Hee-Jun;Eom, Gwang-Moon
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.7
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    • pp.1242-1246
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    • 2016
  • Heel rocking phase in gait cycle is from initial contact to forefoot contact. The purpose of this study was to investigate the effect of age on heel rocking time. Seven young women ($21.9{\pm}1.5yrs$) and seven elderly women ($74.1{\pm}6.7yrs$) participated in this study. Subjects wore the shoes equipped with pressure sensors and walked along 10 m walkway at comfortable speeds. Stride time, stance time, and heel rocking time were compared between groups. Stride time was not different between groups (p=0.087). Stance time was longer (p<0.001) but heel rocking time was shorter in the elderly than in the young (p<0.001). The shorter heel-rocking time in elderly women indicates less efficient shock-absorption in the heel-rocking phase, which might be related to the abnormal control and/or reduced performance of ankle dorsiflexors.

Performance Estimation of Hexagonal Rockfall Protection Net by Numerical Analysis (수치해석을 이용한 육각 낙석방지망의 성능 평가)

  • Oh, Sewook;Park, Soobeom;Kwon, Youngcheul
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.11
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    • pp.53-59
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    • 2014
  • It has been generally recognized that the conventional rockfall protection nets have several problems to actual field application in the aspect of shock absorption, lack of pullout bearing capacities, and net damages. Because of the recognition, authors have tried to develop a new rockfall protection system consisted of shock absorption parts and hexagonal net configuration. In the previous research by the authors, the performance of the newly developed rockfall protection system has been investigated through the laboratory tests and the full-scale testing. In this study, subsequently, numerical analysis program is organized to make a confirmation of the structural stability and performance. For the correct design procedure of the hexagonal net system, it is essential to understand the various mechanical behavior of the entire system. It is also important to be reproduced the systematic characteristics of the system acquired by laboratory and full-scale testing by numerical analysis in order to carry out the numerical experiment to understand various mechanical behavior of the system. As a conclusion, the hexagonal net has better performance in mechanical and physical behavior compared with that of the rectangular net. Furthermore, due to the hexagonal net shows a good performance in aspect of the load distribution, it gives a good alternative in long-term management of the rockfall protection net.