• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.923-924
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• 2010

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.4
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• pp.17-26
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• 2007

In this paper, a theoretical approach is studied to predict structural performances and weight reduction rates of a car-body with shell type sections in case that its materials have to be substituted. For the material substitution design of a car-body, bending, axial and twisting deformations are considered under constant stiffness and strength conditions, which utilize some new indices derived from a structural performance point of view. The developed indices to measure the weight reduction by the material substitution give good guidelines on conceptual design of car-bodies.

• International Journal of Automotive Technology
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• v.8 no.1
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• pp.67-73
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• 2007

This study analyzes the interior noise that is generated during acceleration of a passenger car in terms of car body structure and panel contribution. According to the transfer method, interior noise is classified into structure-borne noise and air-borne noise. Structure-borne noise is generated when the engine's vibration energy, an excitation source, is transferred to the car body through the engine mount and the driving system and the panel of the car body vibrates. When structure-borne noise resonates in the acoustic cavity of the car interior, acute booming noise is generated. This study describes plans for improving the car body structure and the panel form through a cause analysis of frequency ranges where the sound pressure level of the rear seat relative to the front seat is high. To this end, an analysis of the correlation between body attachment stiffness and acoustic sensitivity as well as a panel sensitive component analysis were conducted through a structural sound field coupled analysis. Through this study, via research on improving the car body structure in terms of reducing rear seat noise, stable performance improvement and light weight design before the proto-car stage can be realized. Reduction of the development period and test car stage is also anticipated.

• Journal of Welding and Joining
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• v.34 no.1
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• pp.21-25
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• 2016

The automotive vehicle is made through the following processes such as press shop, welding shop, paint shop, and general assembly. Among them, the most important process to determine the quality of the car body is the welding process. Generally, more than 400 pressed panels are welded to make BIW (Body In White) by using the RSW (Resistance Spot Welding) and GMAW (Gas Metal Arc Welding). Recently, as the needs of light-weight material due to the $CO_2$ emission issue and fuel efficiency, new joining technologies for aluminum, CFRP (Carbon Fiber Reinforced Plastic) and etc. are needed. Aluminum parts are assembled by the spot welding, clinching, and SPR (Self Piercing Rivet) and friction stir welding process. Structural adhesive boning is another main joining method for light-weight materials. For example, one piece aluminum shock absorber housing part is made by die casting process and is assembled with conventional steel part by SPR and adhesive bond. Another way to reduce the amount of the car body weight is to use AHSS (Advanced High Strength Steel) panel including hot stamping boron alloyed steel. As the new materials are introduced to car body joining, productivity and quality have become more critical. Productivity improvement technology and adaptive welding control are essential technology for the future manufacturing environment.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.311-320
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• 2009

Most advanced countries are researching to apply light weight materials far rolling stock because weight reduction for railway body derives cost-saving, energy-saving, and high-speed. Likewise, current Korea rolling stock field makes arduous effects of weight-reduction, miniaturization, and high-efficiency to achieve a high-speed railway. Aluminum becomes suitable material for these projects because it is much lighter than steel or stainless. Manufacturing the railway car body by using the Aluminum is increasing because Aluminum is not bringing the corrosion by unique oxidation-passivate. Aluminum extrusion profile far railway body requires a high mechanical property, accurate shape dimension, and stable quality because the railway body is composed with many different kinds of extruded profiles. Therefore, it is necessary to research about Aluminum precision-extrusion technology to maintain exit temperature and die load. The goal of this project is applying the Aluminum extrusion profile to next-generation railway car body by developing the Aluminum extrusion profile according to precision-extrusion technology which may maintain isothermal exit temperature.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.71-73
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• 2006

Magnesium alloys are becoming important material for light weight car body, due to their low specific density but high specific strength. However they have a poor weldability, caused high oxidization tendency and low vapor temperature. In this study, the laser welding performance of magnesium alloys was investigated for automobile application. The materials were rolled magnesium alloy sheet contains 3%Al and 1%Zn. To evaluate the weldability, we examined the appearance of welding bead. The mechanical property was measured for welded specimen by tensile test. And formability was checked with the Erichsen tester. For the results, the performance of weld in laser welding was enough for press forming such as car body. But it was recommended to use filler wire for reduce the under fill.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.548-553
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• 2008

Low Floor buses have no steps to get on or get off the main cabin to provide the old and the handicapped with easy access. The car body for the low floor bus was designed to consider Korean physical standard, passenger capacity (standee, seated, handicapped), arrangement of vehicle components, and bus law or regulations. It was designed as an one body, without any reinforcement armature, which has light-weight sandwich constructions with glass epoxy skins, aluminum honeycomb cores and inner-frames. In this paper, torsion rigidity of the designed car body was evaluated and compared with that of a car body with reinforcement armatures in the cabin. Finite element method verified that the designed car body without reinforcement armatures could satisfy requirements of torsion rigidity.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.11
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• pp.1297-1308
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• 2011

The light-weight design of UTM (Urban Transit Maglev)-02 car-body frames are performed, based on initial configuration. The thicknesses of fourteen sub-structures are defined as design variables and the loading condition is considered according to weight of sub-structures, electronic and pneumatic modules and passengers. For efficient and robust process of design optimization, objective function and constraints are approximated by response surface approximation. Structural analysis is performed at some sampling points to construct the approximated objective function and constraints composed of design variables. Design space is changed to find many optimal candidates and best optimal design can be found eventually. The Matlab Optimization Toolbox is used to find optimal value and sensitivity analysis about each design variable is also performed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.23 no.5
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• pp.519-524
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• 2014

The use of light weight magnesium alloy offers significant potential towards improvement of the automotive fuel efficiency. However, the application of formed magnesium alloy components in auto-body structures is restricted due to the low formability at room temperature and lack of knowledge for processing magnesium alloys at elevated temperatures. In this study, a warm tensile test of magnesium alloys was performed to measure tensile strength and elongation. An improvement in formability was confirmed at increased temperatures above about $250^{\circ}C$. Car body warm forming technology was conducted for forming forming reinforced dash components of the magnesium alloy AZ31B sheet at elevated temperatures.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.52-54
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• 2003

In automotive industry, light weight vehicle is one of issues because of air pollution. Therefore, automotive manufacturers have tried to apply light materials such as aluminum to car body. Welding aluminum using laser has some advantages good weld quality and high productivity. In this study, light emission which is generated in aluminum 6k21 welding with laser is measured using photodiodes. Analysis of relationship between sensor signals of welding variables and formation of keyhole and plasma is performed.