• 한국철도학회:학술대회논문집
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• 한국철도학회 2001년도 추계학술대회 논문집
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• pp.229-234
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• 2001

The aluminum extruded sections are used to the light construction of the high speed rail vehicle structures. However, the research works on the crashworthy design of aluminum extruded sections are not published sufficiently. In this paper, the collapse characteristics of aluminum extruded sections are investigated by crush test and simulation. The scale model studies are also performed to predict the impact energy absorption characteristics of full scale model through axial crush test and simulation.

• 한국안전학회지
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• 제17권3호
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• pp.7-12
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• 2002

The object of this paper is to investigate collapse characteristics of CF/Epoxy(Carbon Fiber/Epoxy resin) composite tubes on the change of interlaminar number and fiber orientation angle of outer and to evaluate reappearance of collapse characteristics on the change of tension strength of fibers under static and impact axial compression loads. When a CF/Epoxy composite tube is mushed, static/impact energy is consumed by friction between the loading plate and the splayed fiends of the tube, by fracture of the fibers, matrix and their interface. In general, CF/Epoxy tube with 6 interlaminar number(C-type) absorbed more energy than other tubes(A, B, D-types). The maximum collapse load seemed to increase as the interlaminar number of such tubes increases. The collapse mode depended upon orientation angle of outer of CF/Epoxy tubes and loading status(static/impact). Typical collapse modes of CF/Epoxy tubes are wedge collapse mode, splaying collapse mode and fragmentation collapse mode. The wedge collapse mode was shorn in case of CF/Epoxy tubes with 0$^{\circ}$ orientation angle of outer under static and impact loadings. The splaying collapse mode was shown in only case of CF/Epoxy tubes with 90$^{\circ}$ orientation angie or outer under static loadings, however in impact tests those were collapsed in fragmentation mode. So that CF/Epoxy tube with 6 interlaminar number and 90$^{\circ}$ outer orientation angle presented to the optimal collapse characteristics.

• International Journal of Aeronautical and Space Sciences
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• 제14권2호
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• pp.140-145
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• 2013

The development of high performance fabrics have advanced body armor technology and improved ballistic performance while maintaining flexibility. Utilization of the shear thickening phenomenon exhibited by Shear Thickening Fluids (STF) has allowed further enhancement without hindering flexibility of the fabric through a process of impregnation. The effect of STF impregnation on the ballistic performance of fabrics has been studied for impact velocities below 700 m/s. Studies of STF-impregnated fabrics for high velocity impacts, which would provide a transition to significantly higher velocity ranges, are lacking. This study aims to investigate the effect of STF impregnation on the high velocity impact characteristics of Kevlar fabric by effectively dispersing silica nanoparticles in a suspension, impregnating Kevlar fabrics, and performing high velocity impact experiments with projectile velocities in the range of 1 km/s to compare the post impact characteristics between neat Kevlar and impregnated Kevlar fabrics. 100 nm diameter silica nanoparticles were dispersed using a homogenizer and sonicator in a solution of polyethylene glycol (PEG) and diluted with methanol for effective impregnation to Kevlar fabric, and the methanol was evaporated in a heat oven. High velocity impact of STF-impregnated Kevlar fabric revealed differences in the post impact rear formation compared to neat Kevlar.

• 한국자동차공학회논문집
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• 제11권3호
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• pp.155-160
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• 2003

For the weight reduction of vehicle body up to 20∼30% compared to the conventional monocoque steel body·.in-white, most automotive manufacturers have attempted to develop the aluminum intensive body-in-white using an aluminum space frame. In this paper, the crush tests and simulations for the aluminum extrusions filled with the structural from are performed to evaluate the collapse characteristics of that light weighted material. From these studies. the effectiveness of structural for is evaluated in improving automotive crashworthiness. In order to improve the improve energy absorption capability of the aluminum space frame body, safety design modifications are performed and analyzed based on the suggested collapse initiator concepts and on the application of the aluminum extrusions filled with structural foam. The effectiveness of these design concepts on the frontal and side impact characteristics of the aluminum intensive vehicle structure is investigated and summarized.

• Composites Research
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• 제36권4호
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• pp.270-274
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• 2023

필라멘트 와인딩 공정을 사용한 FRP 복합재의 적층 구조는 기존의 FRP 복합재의 적층 구조와는 다를 뿐만 아니라 일반적인 적층 구조를 토대로 기계적 물성에 대해서 분석하고자 한다면 그에 대한 영향을 파악하는 것이 어렵다. 따라서 전반적인 성능을 향상시키기 위해 기계적 물성을 개선하고 교차 적층 구조를 최적화하는 것이 필수적이다. 따라서 본 연구는 비정질 할로이사이트 나노튜브(Amorphous Halloysite Nanotubes, A-HNT)를 5개의 층 배열을 통해 교차 적층 탄소 섬유 강화 플라스틱(CFRP) 구조의 저속 충격 특성에 미치는 영향을 조사하는 것을 목표로 한다. 중량 낙하식 충격시험을 통하여 라미네이트의 저속 충격 특성을 확인하였으며, 충격을 가한 후에 현미경을 통하여 충격 파손 모드와 손상 정도를 비교 평가하였다. 나노 입자의 첨가 여부에 따른 각각의 교차 적층 구조 라미네이트를 10 J과 15 J의 충격에너지에서 비교하였다. 10 J의 경우 흡수에너지는 각 구조에서 비슷한 경향을 보였다. 그에 비해 15 J의 경우 흡수에너지는 각 구조에서 다른 흡수에너지를 가지며, 나노 입자가 첨가되지 않은 구조가 가장 높은 흡수에너지를 가진다. 또한 광학현미경을 통하여 각 구조에서 다양한 충격 파손 모드가 관찰되었다.

• Steel and Composite Structures
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• 제47권5호
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• pp.615-631
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• 2023

Steel corrosion induces structural deterioration of concrete-filled steel tubes (CFSTs), and any potential extreme action on a corroded CFST would pose a severe threat. This paper presents a comprehensive investigation on the lateral impact behaviour of CFSTs suffering from localised pitting corrosion damage. A refined finite element analysis model is developed for the simulation of locally corroded CFSTs subjected to lateral impact loads, which takes into account the strain rate effects on concrete and steel materials as well as the random nature of corrosion pits, i.e., the distribution patterns and the geometric characteristics. Full-range nonlinear analysis on the lateral impact behaviour in terms of loading and deforming time-history relations, nonlinear material stresses, composite actions, and energy dissipations are presented for CFSTs with no corrosion, uniform corrosion and pitting corrosion, respectively. Localised pitting corrosion is found to pose a more severe deterioration on the lateral impact behaviour of CFSTs due to the plastic deformation concentration, the weakened confinement and the reduction in energy absorption capacity of the steel tube. An extended parametric study is then carried out to identify the influence of the key parameters on the lateral impact behaviour of CFSTs with localised pitting corrosion. Finally, simplified design methods considering the features of pitting corrosion are proposed to predict the dynamic flexural capacity of locally pitted CFSTs subjected to lateral impact loads, and reasonable accuracy is obtained.

• Composites Research
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• 제37권1호
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• pp.46-52
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• 2024

운송 수단의 발전은 인간의 교통 편의 증진과 더불어 이동이 불편한 장애인들의 이동 반경 확대를 가능하게 하였다. 그러나 휠체어 탑재 차량의 경우 차량 사고 시 발생할 수 있는 안전성은 일반 승객 좌석에 비해 여전히 낮다. 특히 무방비 상태에서 발생할 수 있는 후방 추돌 사고의 경우 장애인 탑승객의 목 부상에 치명적으로 작용할 수 있다. 따라서 휠체어 탑재 차량에 적용될 headrest에는 보다 세밀한 설계안이 반영되어야 한다. 본 연구에서는 휠체어 운송 차량의 저속 후방 추돌 시 headrest의 국부적 압축 특성 분포 구현을 위해 multi-cell headrest가 제안되었다. 이후 해석을 통한 데이터셋 구축과 k-means clustering을 적용한 군집화 결과를 이용해 탑승객의 목 상해지수와 충격 에너지 흡수량 간 상관관계 분석이 수행되었다. 군집화 결과 유사한 특성을 지닌 데이터 군집이 형성된 것을 확인하였으며, 각 군집의 특성을 통한 목 상해지수와 충격 에너지 흡수량 간의 상관관계 분석이 수행되었다. 분석 결과 Mid3와 Mid6에서의 cell 압축 특성이 soft할수록 충격 에너지 흡수량이 증가하는 것을 확인하였으며, Front2, Mid3, Mid6에서의 cell 압축 특성이 hard할수록 목 상해지수 감소에 효과적임을 확인하였다.

• 한국생산제조학회지
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• 제22권6호
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• pp.976-981
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• 2013

This aims to examine experimentally the absorption behavior and strength of circular CFRP members with different stacking configurations on exposure to a separate impact velocity. In addition, considered the dynamic characteristics. Circular and square CFRP members were prepared from 8-ply unidirectional prepreg sheets stacked at different angles ($0^{\circ}/90^{\circ}$ and $90^{\circ}/0^{\circ}$, where the $0^{\circ}$ direction coincides with the axis of the member) and interface numbers (2, 4, and 6). Based on the collapse characteristics of the circular CFRP members. In this study, for the circular members, the impact energies at crosshead speeds of 5.52 m/s, 5.14 m/s, and 4.57 m/s are 611.52 J, 529.2 J, and 419.44 J (at circular members), respectively. Likewise, for the square members, the impact energies at crosshead speeds of 2.16 m/s, 1.85 m/s, and 1.67 m/s are 372.4 J, 274.4 J, and 223.44 J (at square members).

• Steel and Composite Structures
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• 제17권4호
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• pp.387-403
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• 2014

This paper presents a high accuracy Finite Element approach for delamination modelling in laminated composite structures. This approach uses multi-layered shell element and cohesive zone modelling to handle the mechanical properties and damages characteristics of a laminated composite plate under low velocity impact. Both intralaminar and interlaminar failure modes, which are usually observed in laminated composite materials under impact loading, were addressed. The detail of modelling, energy absorption mechanisms, and comparison of simulation results with experimental test data were discussed in detail. The presented approach was applied for various models and simulation time was found remarkably inexpensive. In addition, the results were found to be in good agreement with the corresponding results of experimental data. Considering simulation time and results accuracy, this approach addresses an efficient technique for delamination modelling, and it could be followed by other researchers for damage analysis of laminated composite material structures subjected to dynamic impact loading.

• 한국군사과학기술학회지
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• 제14권6호
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• pp.986-992
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• 2011

In this paper, the characteristics of shock behavior of multi-layered panels under impact were studied. The panels consist of four different lightweight materials including al, al-foam, rubber and FRP in order to enhance their shock energy absorption. A commercial code, Ls-dyna was used to build the numerical model and study shock behavior based on the analysis of shock response spectrum and peak response acceleration. The reliability of the numerical model was estimated by its comparison with the experimental results acquired under the same impact conditions.