• Journal of the Korean Society for Railway
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• v.7 no.2
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• pp.77-84
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• 2004

In order to determine the most suitable material system for achieving the lightweight design while fulfilling the design requirements of carbody structures of Korean Tilting Train eXpress(TTX), aluminum carbody. composite carbody, and hybrid carbody combined with aluminum and composite structures were considered in the present study. The finite-element analysis was used to verify the design requirements or the TTX carbody structures with the material system considered in the design stages. The stresses in the carbody structures and deflections of underframe against static load cases were used as design criteria. The results show that the hybrid carbody structures are beneficial with regard to weight savings and structural integrity in comparison to aluminum and composite carbody structures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.10a
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• pp.212-215
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• 2004

The hybrid composite carbody structures were considered as the carbody system of Korean Tilting Train eXpress(TTX) to achieve the lightweight design. The TTX carbodies are composed of the carbody shell made of the sandwich composite structure and the undeframe made of the metal structure. The sandwich structures were used to minimize the weight of carbody, and the metal underframe was used to modify the design easily and to keep the strength of underframe by the installation of the electrical equipments. The sandwich carbody structures will be cured in an autoclave. In this paper, the manufacturing processes of the TTX carbody structures were introduced briefly.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.461-466
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• 2004

The hybrid composite carbody structures were considered as the carbody system of Korean Tilting Train eXpress(TTX) to achieve the lightweight design. The TTX carbodies are composed of the carbody shell made of the sandwich composite structure and the undeframe made of the metal structure. The sandwich structures were used to minimize the weight of carbody, and the metal underframe was used to modify the design easily and to keep the strength of underframe by the installation of the electrical equipments. The sandwich carbody structures will be cured in an autoclave. In this paper, the manufacturing processes of the TTX carbody structures were introduced briefly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.807-815
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• 2004

In order to evaluate the static stability of hybrid carbody structures of Korean Tilting Train eXpress(TTX) caused by degradation of composites under ground environments, T300/AD6005 graphite/epoxy composite specimens were exposed to accelerated environmental conditions including ultraviolet radiation, temperature and moisture fer 2000 hours. It was found that the stiffness and strength of composites after aging were lower than those of unexposed specimens, and decreased as the aging time increases. The values of the degraded properties were used in the static analysis to check the static stability of hybrid carbody structures caused by environmental degradation of composites. The results shown that the structural stability of hybrid carbody structures was affected by the degradation of composites after exposure to accelerated aging environments.

• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.251-256
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• 2006

This paper explains manufacturing process, analysis and experimental studies on a hybrid composite carbody of Korean tilting train. The composite carbody with length of 23m was manufactured as a sandwich structure composed of a aluminium honeycomb core and woven fabric carbon/epoxy faces. In order to evaluate deformational behavior of the composite carbody, the static load test under vertical load has been conducted. From the test, the vertical deflection an겨 cross sectional deformation of the carbody were analysed and measured. The maximum deflection along the side sill was 9.25mm in the experiment and 8.28mm in the analysis. The maximum cross sectional deformation was measured 5.42mm at carbody center in lateral direction and 4.06mm at roof center in vertical direction.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.462-467
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• 2004

In order to determine the most suitable material system which can achieve the lightweight design and fulfill the design requirements of carbody structures of Korean Tilting Train eXpress (TTX), aluminum carbody, composite carbody, and hybrid carbody combined with aluminum and composite structures were considered in present study. The finite-element analysis was used to verity the design requirements of the TTX carbody structures with the material system being considered in the design stages. The stresses in the carbody structures and deflections of underframe against static load cases were checked as design criteria. The results show that the hybrid carbody structures are beneficial with regard to weight savings and structural integrity when compared to aluminum and composite carbody structures.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.207-211
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• 2005

The Korean Tilting Train eXpress (TTX) with service speed of 180km/h have been developing using hybrid design concept combined with a sandwich composite structure for the carbody and stainless steel structure for the underframe to match the challenging demands with respect to cost efficient lightweight design for railway carriage structures. The sandwich composite structure was used to minimize the weight of the carbody, while the metal underframe was used to modify the design easily and to keep the strength of underframe for the installation of the electrical equipments. The sandwich composite structure was 23 meters long, 3 meters wide and 2.7 meters high, and cured as one body in a large autoclave equipment with the length of 30 meters and the diameter of 5 meters. The joint part between the carbody structure made of sandwich composites and the metal underframe was joined by the proposed design.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1099-1107
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• 2013

This study proposes a weight reduction design for urban transit, specifically, a Korean EMU carbody made of aluminum extrusion profiles, according to size optimization and useful material changes. First, the thickness of the under-frame, side-panels, and end-panels were optimized by the size optimization process, and then, the weight of the Korean EMU carbody could be reduced to approximately 14.8%. Second, the under-frame of the optimized carbody was substituted with a frame-type structure made of SMA 570, and then, the weight of the hybrid-type carbody was 3.8% lighter than that of the initial K-EMU. Finally, the under-frame and the roof-panel were substituted with a composite material sandwich to obtain an ultralight hybrid-type carbody. The weight of the ultralight hybrid-type carbody was 30% lighter than that of the initial K-EMU. All the resulting carbody models satisfied the design regulations of the domestic Performance Test Standard for Electrical Multiple Unit.

• Composites Research
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• v.18 no.6
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• pp.19-25
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• 2005

This paper has performed an experimental study on the hybrid composite carbody of Korean tilting railway vehicle. The hybrid composite carbody has the length of 23m and is comprised of a 40mm-thick aluminium honeycomb core and 2mm-thick woven fabric carbon/epoxy face sheet. In order to evaluate the structural behavior and safety of the hybrid composite carbody, the static load tests such as vertical load, end compressive load, torsional load and 3-point support load tests have been conducted. The test was performed under Japanese Industrial Standard (JIS) 17105 standard. from the tests, the maximum deflection was 12.3mm and the equivalent bending stiffness of the carbody was $0.81\times10^{14}\;kgf{\cdot}mm^2$. The maximum strain of the composite body was below $20\%$ of failure strain of the carbon/epoxy face sheet.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.11
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• pp.1335-1343
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• 2012

In this study, the lightweight modular design of hybrid railway carbody structures made of sandwich composites and aluminum extrusions was investigated by using topology and size optimization techniques. The topology optimum design was used to select the best material for parts of the carbody structure at the initial design stage, and then, the size optimum design was used to find the optimal design parameters of hybrid carbody structures using first-order and sub-problem methods. Through the topology optimization analysis, it was found that aluminum extrusions were suitable for primary members such as the underframe and lower side panel module to improve the stiffness and manufacturability of the carbody structures, and sandwich composites were appropriate for secondary members such as the roof and middle side panel module to minimize its weight. Furthermore, the results obtained by size optimization analysis showed that the weight of hybrid carbody structures composed of aluminum extrusions and sandwich composites could be reduced by a maximum of approximately 17.7% in comparison with carbody structures made of only sandwich composites.