• Title/Summary/Keyword: LS-DYNA-3D

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Development of Structural Analysis System of Bow Flare Structure(2) - Prediction of Wave Impact Load Area - (선수 구조부 구조해석 시스템 개발(2) - 파랑충격하중 면적의 추정 -)

  • S.G. Lee;J.W. Park
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.4
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    • pp.87-94
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    • 1999
  • Empirical design is still used to avoid a structural damage because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The damage due to wave impact load is largely affected by impact pressure impulse and impact load area. The objective of this study is, as the second step, to develop an efficient scantling program of bow flare structure, and to predict its impact load area by comparing maximum dented deformations at center of idealized panel structure model of bow flare structure of 300k DWT VLCC using LS/DYNA3D code, which will be used for its verification of dynamic structural analysis, as the next step. Through this study, the impact load area was estimated as $1.5s{\times}1.5s$ stiffener space(s) in the case of panel with stiffeners and as $2.5s{\times}2.5s$, with stringers, under impact pressure curve with peak height 6.5MPa, tail height 1.0MPa, and duration time 5.0msec.

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Development of Structural Analysis System of Bow Flare Structure(1) - Prediction of Wave Impact Load Characteristics - (선수 구조부 구조해석 시스템 개발(1) - 파랑충격하중 특성의 추정 -)

  • S.G. Lee;M.S. Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.36 no.4
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    • pp.77-86
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    • 1999
  • The bow flare structure of a ship is designed considering wave impact loads largely caused by relative motion of the ship and wave at rough sea. Empirical design is still used because impact phenomenon and structural behaviour due to wave impact load can not examined accurately. The objective of this study is, as the first step, to predict wave impact loads giving the structural damages to the bow flare structure from the damage data inversely, using dynamic nonlinear finite element code LS/DYNA3D, and to perform various parametric studies of wave impact pressure curve for its characteristics, such as peak height, duration time, tail height, rise time, etc.. The followings were obtained from this study: Dynamic structural responses against wave impact loads are largely affected by impact pressure impulse whose amount during duration time until peak deformation is very important.

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An Evaluation of Structural Integrity and Crashworthiness of Automatic Guideway Transit(AGT) Vehicle made of Sandwich Composites (샌드위치 복합재 적용 자동무인경전철 차체 구조물의 구조 안전성 및 충돌 특성 평가 연구)

  • Ko, Hee-Young;Shin, Kwang-Bok;Cho, Se-Hyun;Kim, Dea-Hwan
    • Composites Research
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    • v.21 no.5
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    • pp.15-22
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    • 2008
  • This paper describes the results of structural integrity and crashworthiness of Automatic Guideway Transit(AGT) vehicle made of sandwich composites. The applied sandwich composite of vehicle structure was composed of aluminum honeycomb core and WR580/NF4000 glass fabric/epoxy laminate composite facesheet. Material testing was conducted to determine the input parameters for the composite facesheet model, and the effective equivalent damage model fer the orthotropic honeycomb core material. The finite element analysis using ANSYS v11.0 was dont to evaluate structural integrity of AGT vehicle according to JIS E 7105 and ASCE 21-98. Crashworthiness analysis was carried out using explicit finite element code LS-DYNA3D with the lapse of time. The crash condition was frontal accident with speed of 10km/h at rigid wall. The results showed that the structural integrity and crashworthiness of AGT vehicle were proven under the specified loading and crash conditions. Also, the modified Chang-Chang failure criterion was recommended to evaluate the failure modes of composite structures after crashworthiness event.

A Study on Crashworthiness and Rollover Characteristics of Low-Floor Bus made of Honeycomb Sandwich Composites (하니컴 샌드위치 복합재를 적용한 저상버스의 충돌 및 전복 특성 연구)

  • Shin, Kwang-Bok;Ko, Hee-Young;Cho, Se-Hyun
    • Composites Research
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    • v.21 no.1
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    • pp.22-29
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    • 2008
  • This paper presents the evaluation of crashworthiness and rollover characteristics of low-floor bus vehicles made of aluminum honeycomb sandwich composites with glass-fabric epoxy laminate facesheets. Crashworthiness and rollover analysis of low-floor bus was carried out using explicit finite element analysis code LS-DYNA3D with the lapse of time. Material testing was conducted to determine the input parameters for the composite laminate facesheet model, and the effective equivalent damage model for the orthotropic honeycomb core material. The crash conditions of low-floor bus were frontal accident with speed of 60km/h. Rollover analysis were conducted according to the safety rules of European standard (ECE-R66). The results showed that the survival space for driver and passengers was secured against frontal crashworthiness and rollover of low-floor bus. Also, The modified Chang-Chang failure criterion is recommended to predict the failure mode of composite structures for crashworthiness and rollover analysis.

Simulation of Low Velocity Impact of Honeycomb Sandwich Composite Panels for the BIMODAL Tram Application (바이모달 트램 적용 하니컴 샌드위치 복합재 패널의 저속 충격 해석)

  • Lee, Jae-Youl;Jeong, Jong-Cheol;Shin, Kwang-Bok
    • Composites Research
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    • v.20 no.4
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    • pp.42-50
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    • 2007
  • This paper describes the results of experiments and numerical simulation studies on the low-velocity impact damage of two different sandwich composite panels for application to bodyshell and floor structure of the BIMODAL tram vehicle. Square test samples of 100mm sides were subjected to low-velocity impact loading using an instrumented testing machine at four impact energy levels. Part of this work presented is focused on the finite element analysis of low-velocity impact response onto a sandwich composite panels. It is based on the application of explicit finite element (FE) analysis codes LS-DYNA 3D to study the impact response of sandwich structures under low-velocity impact conditions. Material testing was conducted to determine the input parameters for the metallic and composite material model, and the effective equivalent damage model for the orthotropic honeycomb materials. Numerical and experimental results showed a good agreement for damage area and the depth of indentation of sandwich composite panels created by the impact loading.

Study on the Axial Crushing Behaviors of UD Kevlar/Epoxy and Carbon-Kevlar/Epoxy Composite Tubes (단방향 케블라/에폭시, 탄소-케블라/에폭시 복합재 튜브의 축방향 압괴 거동에 대한 연구)

  • Kim, Hyung-Uk;Kim, Jung-Seok;Jung, Hyun-Seung;Yoon, Hyuk-Jin;Kwon, Tae-Soo
    • Journal of the Korean Society for Railway
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    • v.13 no.3
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    • pp.271-277
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    • 2010
  • In this paper, a numerical model for a Kevlar/Epoxy and Carbon-Kevlar/Epoxy tube used as an energy absorbing component has been developed and then results have been verified through experiment. The 2D shell element and Chang-Chang failure criterion of LS-DYNA that is commercial explicit FE code was used. Mechanical material properties for the model were obtained by material testing in advance. The numerical results were compared with quasi-static test results under axial compressive loading at 10mm/min. From the results, in the case of the Kevlar/Epoxy tube, load-crushed displacement curves were very close to the experiments and SEA (specific energy absorption) shows a good agreement with experimental one within less than 6%. However, the Carbon-Kevlar/Epoxy tube shows some differences with the experimental results.

3-Dimensional Finite Element Method Analysis of Blanking Die for Lead Frame (리드프레임의 전단용 금형에 대한 3차원 FEM 해석)

  • Choi, Man-Sung
    • Journal of the Semiconductor & Display Technology
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    • v.10 no.3
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    • pp.61-65
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    • 2011
  • The capabilities of finite elements codes allow now accurate simulations of blanking processes when appropriate materials modelling are used. Over the last decade, numerous numerical studies have focused on the influence of process parameters such as punch-die clearance, tools geometry and friction on blanking force and blank profile. In this study, three dimensional finite element analysis is carried out to design a lead frame blanking die using LS-Dyna3D package. After design of the blanking die, an experiment is also carried out to investigate the characteristics of blanking for nickel alloy Alloy42, a kind of IC lead frame material. In this paper, it has been researched the investigation to examine the influence of process parameters such as clearance and air cylinder pressure on the accuracy of sheared plane. Through the experiment results, it is shown that the quality of sheared plane is less affected by clearance and air cylinder pressure.

Comparison of UNDEX Whipping Response of Hull Girder according to Modeling Methods (해석모델링 방법에 따른 선체거더의 수중폭발 휘핑응답 비교)

  • Kwon, Jeong-Il;Chung, Jung-Hoon;Lee, Sang-Gab
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.6 s.144
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    • pp.631-636
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    • 2005
  • One and three dimensional whipping response analyses of a naval surface combatant subjected to an underwater explosion bubble pulse were carried out to compare the efficiency and accuracy according to the modeling methods. In 1-D analysis, program UNDEXWHIP developed by KIMM was used, which is based on the thin-walled Timoshenko's beam theory and on the modal analysis method using wetted vibratory modes of the hull girder. In 3-D analysis, three finite element models were suggested using LS-DYNA/USA code, such as 3-D beam model considering geometric shape of wetted side shell, coarse and fine 3-D F.E. models. Through the comparison of results from the 1-D and 3-D analyses, it could be confirmed that 1-D analysis result is in good agreement with 3-D analysis ones, and that fine 3-D F.E. model, shock analysis one, is also used both in the shock response and whipping response analyses for the analyst effort and time savings.

Numerical Analysis on Penetration Reduction of a WHA Penetrator by an Impact of Linear Explosively Formed Penetrator(LEFP) (선형폭발성형탄(LEFP) 충격에 의한 WHA 관통자의 관통성능 감소에 관한 수치해석 연구)

  • Joo, Jaehyun;Choi, Joonhong;Koo, ManHoi;Kim, Dongkyu
    • Journal of the Korea Institute of Military Science and Technology
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    • v.20 no.3
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    • pp.384-392
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    • 2017
  • A linear explosively formed penetrator(LEFP) is a modification of the explosively formed penetrator(EFP). An EFP is axisymmetric and has a dish-shaped liner while LEFP has a rectangular-shaped liner with curved cross section. Upon detonating LEFP forms laterally wide projectile like blade, leaving a long penetration hole on the target. On the other hand, a long-rod tungsten heavy alloy(WHA) penetrator is one of the major threats against most of the ground armored vehicles. In this paper, the feasibility of using an LEFP in protecting against a long-rod WHA penetrator by colliding LEFP into the threat was investigated through a set of numerical simulations. In this study, a scale-down WHA penetrator with length to diameter ratio(L/D) of 10.7 and 7.0 mm diameter was used to represent a long-rod WHA penetrator. LS-DYNA and Multi-Material ALE technique were employed for the simulation. For estimation of the protection effect by LEFP, residual penetration depths into RHA by the threat were compared according to various impact locations against the threat.

Optimum Design of A-Pillar Trim for Occupant Protection (승원 안전을 고려한 승용차 A-Pillar Trim의 최적 설계)

  • 김형곤;강신일
    • Transactions of the Korean Society of Automotive Engineers
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    • v.9 no.2
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    • pp.99-106
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    • 2001
  • NHTSA has been conducting biomechanical studies to reduce inujuries sustained sustained during automotive collision. Furthermore, NHTSA added the regulation to the FMVSS 201, limiting the equivalent HIC(Head Injury Criterion) value under 1000. In the presont work, a methodology was developed for the optimum design of the A-pillar trim with rib-structures. The design variables for the rib-strucrures were the transverse spacing, the longitudinal spacing, and the thickness. The required sets of the design varibles were decided based on the design of experiments. The head impact simulations were carried out using the LS-DYNA3D, and the HIC(d) values were computed using the resulrs of the head impact simulation. The objective function was constructed using the response surface methed (RSM). When the obtained optimum values were not inside the region of interest, the design proceduers were repeated by changing the region of interest. Finally, an A-pillar trim with rib-structures, which resulred in HIC(d) value under 850 for 15 mph head-trim impact, was developed.

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