• 한국자동차공학회논문집
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• 제13권2호
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• pp.157-161
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• 2005

In the FY 2003, the number of registered vehicles in Korea reached 14 million, which is 7.7% increase from the previous year. The increase of number of vehicles has caused a lot of social problem with enormous costs. The social costs related to the vehicles includes environmental costs resulting from pollution and scraping of vehicles, those resulting from life-saving and repairing from car accidents and so on. There have been m any efforts to reduce the social costs in m any areas. As a part of the efforts, there are recent grow ing interests on the damageability & repairability in related industries. In this study, we investigated the cases of two different types of bum per stay. Futhermore, we analyzed their effects on damageability & repairability and reduction of repair cost. So we found that if the manufacturers design new cars with good damageability & repairability, then the total repair cost in crash will be reduced.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.659-666
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• 2007

In the present study, a numerical analysis of the three-dimensional heat transfer and fluid flow for a vehicle cooling system was developed. The flow field of the engine room between the grille and radiator was analyzed. The results show that, as the airflow inlet grille angle $\alpha$ is varied from $15^{\circ}$ to $-15^{\circ}$, the air flow rate compared with $\alpha=0^{\circ}$(horizontal) changes from -11.9% to +5.1%; while the heat flux from the radiator changes from -9.2% to +4.4%. When the airflow inlet bumper angle $\beta$ is varied from $-5^{\circ}$ to $+15^{\circ}$, the heat flux from the radiator compared with $\beta=0^{\circ}$(horizontal) increases up to +4.4%. When the airflow inlet grille angle $\alpha=-15^{\circ}$ and the bumper grill angle $\beta=+15^{\circ}$, the airflow rates and heat flux compared with($\alpha=0^{\circ}$, $\beta=0^{\circ}$) can be increased to +9.5% and +7.5%, respectively. The results indicate that the optimal angles for cooling efficiency are used.

• 대한기계학회논문집A
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• 제33권5호
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• pp.502-507
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• 2009

Curvature extrusion process has several advantages in comparison to the conventional extrusion and bending process. In the curvature extrusion, the extruded part is directly bent during extrusion. Therefore, it does not need additional bending process after extrusion. In the curvature extrusion process, it is possible to produce curved extruded products that have a constant or various curvatures. It is essential that we predict the curvatures of the extruded product to meet the required curvatures. This paper proposed a theoretical model that can predict the curvature of extruded product produced by the curvature extrusion process. Using the proposed model the movement of guide tool that causes the bending of extruded product was controlled to produce the required curved automotive Al bumper back beam. The effectiveness of the proposed prediction model and the movement of guide tool were verified by the FE analysis and curved extrusion experiment.

• Steel and Composite Structures
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• 제24권3호
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• pp.351-358
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• 2017

Due to the increasing competition, automotive manufacturers have to manufacture highly safe and light vehicles. The parts which make up the body of the vehicle and absorb the energy in case of a crash, are usually manufactured with sheet metal forming methods such as deep drawing, bending, trimming and spinning. The part may get thinner, thicker, folded, teared, wrinkled and spring back based on the manufacturing conditions during manufacturing and the type of application methods. Transferring these effects which originate from the forming process to the crash simulations that are performed for vehicle safety simulations, makes accurate and reliable results possible. As a part of this study, firstly, the one-step and incremental sheet metal forming analysis (deep drawing + trimming + spring back) of vehicle front bumper beam and crash boxes were conducted. Then, crash performances for cases with and without the effects of sheet metal forming were assessed in the crash analysis of vehicle front bumper beam and crash box. It was detected that the parts absorbed 12.89% more energy in total in cases where the effect of the forming process was included. It was revealed that forming history has a significant effect on the crash performance of the vehicle parts.

• 소성∙가공
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• 제25권5호
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• pp.319-324
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• 2016

Recently, the roll forming process is one of the most widely used processes for manufacturing automotive part. In this study, flower patterns of roll forming process were designed to manufacture an ultra high strength bumper beam using the finite element analysis. Three types of flower patterns such as the basic type, the rotation type and the split type were designed based on the constant arc length forming method using the design software, UBECO Profil. Finite element analysis was performed to evaluate the suitability of designed flower patterns in terms of the longitudinal strain and the bow defect. The analytical results show that the split type represents more uniform longitudinal strain distributions and a good dimensional accuracy than other types of flower patterns.

• Macromolecular Research
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• 제17권11호
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• pp.886-893
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• 2009

Surface modifications using a radio frequency Ar-plasma treatment were performed on a polypropylene (PP) blend used for automotive bumper fascia. The surface characterization and morphology were examined. With increasing aging time, there was an increase in wettability, oxygen containing polar functional groups (i.e., C-O, C=O and O-C=O) due to oxidation, the amount of tale, and bearing depth and roughness on the PP surface, while there was a decrease in the number of hydrocarbon groups (i.e., C-C and C-H). AFM indicated that the Ar-plasma-treatment on a PP blend surface transforms the wholly annular surface into a locally dimpled surface, leading to an improvement in wettability. SEM showed that the PP layer observed in the non-plasma-treated sample was removed after the Ar-plasma treatment and the rubber particles were exposed to the surface. The observed surface characterization and morphologies are responsible for the improved wettability and interfacial adhesion between the PP blend substrate and bumper coating layers.

• 한국ITS학회 논문지
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• 제16권5호
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• pp.85-95
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• 2017

본 논문의 목적은 트럭과 보행자의 충돌사고에서 트럭의 중량, 속도와 범퍼 높이가 보행자 전도거리에 미치는 영향을 분석하고, 나아가 이를 이용한 보행자 전도거리에 대한 모형식을 제시하는 데 있다. 이를 위해 교통사고 재현 프로그램인 PC-crash를 이용하여 트럭의 중량을 5t, 15t, 25t으로 적용하고, 각 트럭의 앞 범퍼 하단 높이를 0.3m부터 0.6m까지 0.1m씩 높여감과 동시에 트럭의 속도를 10km/h부터 100km/h까지 10km/h씩 높여가며 실험하였다. 트럭의 속도와 범퍼 높이는 보행자 전도거리에 유의한 변수로 확인되었고, 트럭 중량은 보행자 전도거리에 유의하지 않은 변수로 나타났다. 또한 다중회귀분석을 이용하여 제시한 모형식은 조정된 $R^2$ 값이 93.3%로 매우 우수한 설명력을 가지는 것으로 나타났다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.137-138
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• 2006

TPOs based on polypropylene has been dominating materials in hard automotive parts such as in bumper fascia, instrumental panel and door trim panel owing to their variety of advantages compared to engineering plastics and steels for years. Recently as environmental regulations related to recycle have been strengthened, the use of TPOs in soft automotive parts such as instrument panel skin and door trim skin is being required much more.. Therefore, in this study, we' d like to give an overview of soft TPOs and introduce soft TPO materials requirement and preferable materials composition by vacuum thermoforming and powder slush molding, respectively.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.337-340
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• 2006

Aluminum extruded profiles have been mostly used only a few automotive parts until now, such as roof rail, sunroof frame and bumper beams. However, Aluminum Extru-form technology, which was recently developed by foreign advanced manufacturer, made it possible to apply the aluminum extruded profiles to suspension parts of passenger and RV cars. It could be obtained by optimized billet casting, extrusion and stretch bending technology. It was possible to have the excellent weight reduction and the competitive price comparing with conventional process of aluminum for automotive parts. Combining additional process technology such as machining and joining, the application can be extended to various automotive parts. We have developed high strength aluminum alloy and fabricated subframe and suspension arm by extruforming process.

• Composites Research
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• 제12권5호
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• pp.23-30
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• 1999

Fiber reinforced composite materials are widely used in automotive industry to produce parts that are large, thin, lightweight, strong and stiff. It is very important to know a charge shape in order to have good products in the compression molding. In particular, the product such as a bumper beam is composed of the random and unidirectional fiber mats. The characteristics of flow fronts such as a bulging phenomenon for random mat and unidirectional fiber mat and slip parameters are studied numerically. And the effects of viscosity ratio and stack type on mold filling parameters are also discussed.