• 한국자동차공학회논문집
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• 제24권2호
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• pp.191-197
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• 2016

RCAR low speed impact test estimates repair cost of the impacted vehicle. In this study, for a mid-size vehicle front body model, structural performance for RCAR low speed impact were analyzed with changing the bumper stay shape and size. First, for improving the impact load transfer mechanism to side member the stay rear section shape at connecting area with side member was modified and the stay outer was redesigned to be normal to the barrier. Next, the investigation on stay thickness effect was carried out and the performances of several models with different forming shape were compared. The final design showed 13mm decrease in the maximum barrier intrusion distance and greatly reduced side member deformation. Additional analyses explained the validity of the final design.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1155-1162
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• 2012

알루미늄 크래쉬 박스는 저속충돌조건에서 프론트 사이드 멤버를 변형을 방지하기 위한 부품이다. 본 연구에서는 저속충돌조건에서 비드형상이 알루미늄 크래쉬 박스의 충돌성능에 미치는 영향을 분석하였다. Edge concave, surface convex 와 surface concave 타입의 비드형상들에 대한 충돌해석 및 실험을 수행하여 비드가 없는 normal 타입의 알루미늄 크래쉬 박스의 충돌성능과 비교분석하였다. 충돌성능은 저속충돌조건에서 크래쉬 박스의 초기 최대하중 및 충돌에너지 흡수능으로 평가하였다. 이를 검증하기 위해 알루미늄 크래쉬 박스와 결합된 프론트 사이드 멤버에 대해 저속충돌실험 수행하고, 이를 분석하였다. Surface concave 타입의 비드가 삽입된 알루미늄 크래쉬 박스 경우, 프론트 사이드 멤버의 변형을 방지할 수 있음을 확인하였다.

• 자동차안전학회지
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• 제10권2호
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• pp.6-12
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• 2018

Optimized section shape of aluminum bumper backbeam for enhancing the front high speed crashworthiness was investigated. Front body analysis model of a convertible vehicle was built up and parameter studies were carried out with changing the inner rib shape and the section thickness distribution. First an inner rib shape displaying most efficient structural performance was selected. Next, for the selected section the effect of section thickness combination was examined. Also, a light weighed backbeam section displaying crash performance over the current design was suggested. Finally RCAR front low speed impact analyses were carried out for the optimized models.

• 한국정밀공학회지
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• 제23권9호
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• pp.149-155
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• 2006

This paper is concerned with the weight reduction of front side member of a vehicle considering the application of high strength steel sheet. The influence of steel sheet grade and thickness on the energy absorption, impact load and deformed shape of front side member is investigated by using reverse engineering and FE-analysis. The reverse engineering is applied to obtain 3D model of front side member from B.I.W for the FE simulation. FE analysis is carried out with commercial crash analysis SW PAM-CRASH. The crashworthiness of front side member is considerably improved with steel sheet strength and thickness increase. From the result of this study the weight reduction in automotive parts for the improvement of the fuel efficiency can be easily achieved with replacing high strength steel without deterioration of crashworthiness.

• 한국생산제조학회지
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• 제20권2호
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• pp.169-173
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• 2011

Crash box is introduced to vehicle design to improve the impact performance and reduce the damage of vehicle body at impact speed. The crash box behind bumper can absorb impact energy effectively to improve vehicle safety. Repair cost at collision accident can be cut down by use of this box. The configuration of car body must be designed by considering the characteristic of material due to the deformation of car body happened at impact. Many papers have been published about material of crash box all over the world. The study of crash box with tube expansion type has been going on Korea. This study is done by the simulation analysis about front collisions against 5 kinds of aluminum crash boxes with the basic structure of square section.

• Composites Research
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• 제31권3호
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• pp.83-87
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• 2018

An object in the Low Earth Orbit (LEO) is affected by many environmental conditions unlike earth's surface such as, Atomic oxygen (AO), Ultraviolet Radiation (UV), thermal cycling, High Vacuum and Micrometeoroids and Orbital Debris (MMOD) impacts. The effect of all these parameters have to be carefully considered when designing a space structure, as it could be very critical for a space mission. Polybenzimidazole (PBI) is a high performance thermoplastic polymer that could be a suitable material for space missions because of its excellent resistance to these environmental factors. A thin coating of PBI polymer on the carbon epoxy composite laminate (referred as CFRP) was found to improve the energy absorption capability of the laminate in event of a hypervelocity impact. However, the overall efficiency of the shield also depends on other factors like placement and orientation of the laminates, standoff distances and the number of shielding layers. This paper studies the effectiveness of using a PBI coating on the front bumper in a multi-shock shield design for enhanced hypervelocity impact resistance. A thin PBI coating of 43 micron was observed to improve the shielding efficiency of the CFRP laminate by 22.06% when exposed to LEO environment conditions in a simulation chamber. To study the effectiveness of PBI coating in a hypervelocity impact situation, experiments were conducted on the CFRP and the PBI coated CFRP laminates with projectile velocities between 2.2 to 3.2 km/s. It was observed that the mass loss of the CFRP laminates decreased 7% when coated by a thin layer of PBI. However, the study of mass loss and damage area on a witness plate showed CFRP case to have better shielding efficiency than PBI coated CFRP laminate case. Therefore, it is recommended that PBI coating on the front bumper is not so effective in improving the overall hypervelocity impact resistance of the space structure.

• International Journal of Precision Engineering and Manufacturing
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• 제4권2호
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• pp.23-29
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• 2003

The spot welded sections of automobiles (hat and double hat shaped sections) absorb most of the energy in a front-end collision. The target of this paper is to analyze the energy absorbing capacity of the structure against the front-end collision, and to obtain useful information for designing stage. Changed the spot welded pitches on the flanges, the hat and double hat shaped section members were tested on the axial collapse loads at various impact velocities. It was expected that para-closed sections would show collapse characteristics which be quite different from those of perfectly closed sections. Hat shaped section members were tested at the impact collapse velocities of 4.72m/sec, 6.54m/sec and 7.1m/sec and double hat shaped section members were tested at the impact collapse velocities of 6.54m/sec, 7.1 m/sec and 7.27m/sec.

• Journal of Welding and Joining
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• 제20권6호
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• pp.78-78
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• Journal of Welding and Joining
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• 제20권6호
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• pp.802-808
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• 2002

Front-side members are structures with the greatest energy absorbing capability in a front-end collision of vehicles. This paper was performed to analyze initial collapse characteristics of spot welded hat and double hat-shaped section members, which are basic shape of side members, on the shift of flange weld pitches. The impact collapse tests were carried out by using home-made vertical air compression impact testing machine, and impact velocity of hat-shaped section members is 4.17m/sec and that of double hat-shaped section members is 6.54m/sec. In impact collapse tests, the collapsed length of hat-shaped section members was about 45mm and that of double hat-shaped section members was about 50mm. In consideration of these condition, axial static collapse tests(0.00017m/sec) of hat and double hat-shaped section members were carried out by using UTM which was limited displacement, about 50mm. As the experimental results, to obtain the best initial collapse characteristics, it is important that stiffness of vehicle members increases as section shapes change and the progressively folding mode induces by flange welding pitch.

• 산업경영시스템학회지
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• 제35권2호
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• pp.52-56
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• 2012

Recently, the pedestrian protection regulations of Europe and Japan are becoming more stringent. However, it is difficult to evaluate the performance of protection because each regulation has different test conditions such as dummy, impact speed and so on. In this study, we construct a finite element model of pedestrian lower legform impactor prescribed in EEVC (European Experimental Vehicle Committee) W/G 10, and performed a impact analysis between the impactor and the front end module of vehicle. The simulations are carried out by using LS-DYNA3D, which is a well-known nonlinear dynamic simulation software. The analysis results according to various impact location show the impact characteristics of the lower legform.