• Transactions of Materials Processing
• /
• v.18 no.1
• /
• pp.73-79
• /
• 2009

In order to investigate the formability of friction stir welded(FSW) tailor welded blanks(TWB) with respect to the base material's directional combination, aluminum alloy AA6111-T4 sheets were welded with three different conjoining types: RD-RD, TD-RD and TD-TD. Here, RD and TD represent rolling and transverse directions, respectively. For experimental formability study, three tests with gradual complexity were performed: the simple tension test with various weld line directions for uni-axial elongation, the hemisphere dome stretching test for biaxial stretching and the cylindrical cup deep drawing test. As a result, all three forming tests showed that RD-RD type samples exhibited the best formability, while TD-TD type sheets showed the least formability performance.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2011.05a
• /
• pp.207-207
• /
• 2011

The numerical simulation of the Forming Limit Diagram(FLD) test was carried out to calculate the limiting dome height(LDH: ISO12004-2) for aluminum alloy sheet Al6061-T6. The finite element analysis was used as an effective method for evaluating formability and diagnosing possible production problems in sheet stamping operations. To predict fracture during the stamping process, several failure models such as Cockcroft-Latham, Rice-Tracey, Brozzo and ESI-Wilkins-Kamoulakos(EWK) criteria were applied. The predicted results were discussed and compared with the experiments for Al6061-T6.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.17 no.6
• /
• pp.164-169
• /
• 2018

In this study, we solved the human hazard problem of aluminum liner by applying plastic PET liner which is widely used as a material for food and beverage containers in the market. In order to reinforce dome area by using low strength / high elongation plastic liner, The aluminum boss was covered on the plastic liner surface. In order to predict the performance of the developed product, the structural analysis was carried out by applying the three - dimensional laminated solid element, and the soundness of the product was verified through the prototype performance test.

• Journal of architectural history
• /
• v.9 no.3 s.24
• /
• pp.51-69
• /
• 2000

This study tries to analyze the development of architectural technologies appeared in several tall buildings and large spatial structures from 1955 to 1999 in Korea. We suppose that these buildings represent the development of technology in Korean modern architecture. By the detailed analysis of these buildings, we can arrive at a conclusion as such; During the years 1955-1999, there existed a great changement in the eighties. We can find this fact very well in the domain of structural system and curtain wall system. In large spatial structures, the structural-system of shell and steel truss dome was replaced by that of space frame, space truss and cable truss with membrane. In tall building, the structural system of rigid frame and shear wall was replaced by tubular system, core and outrigger system. Korean architects introduced the aluminum curtain wall in the sixties, but its low technological level caused many problems in reality. Therefore, precast concrete curtain wall appeared from seventies as the main method for an outer wall in tall building. With the augmentation of height after 1980, PC curtain wall was replaced by the aluminum curtain wall of unit type and structural glass wall system. These systems help to stress the transparency in a tall building.

• Transactions of Materials Processing
• /
• v.20 no.7
• /
• pp.512-517
• /
• 2011

TRB(Tailor Rolled Blank) is an emerging manufacturing technology by which engineers are able to change blank thickness continuously within a sheet metal. TRB door inner panels with required larger thicknesses can be used to support localized high loads. In this study, the aluminum alloy 5J32 TRB sheet is used for a door inner panel application. The TRB material properties were varied by using three heat treatment conditions. In order to predict the failure of the aluminum TRB during simulation, the forming limit diagram, which is used in sheet metal forming analysis to determine the criterion for failure, was investigated. Full-field photogrammetric measurement of the TRB deformation was performed with an ARAMIS 3D system. A FE model of the door inner panel was created using Autoform software. The material properties obtained from the tensile tests were used in the numerical model to simulate the door inner of AA 5J32 for each heat treatment condition. After finite element analysis for the evaluation of formability, a prototype front door panel was manufactured using a hydraulic press.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.18 no.12
• /
• pp.1-6
• /
• 2019

Aluminum liners used in cylinders are hazardous for human health. In this study, we use a plastic PA liner inside cylinders to solve this problem. Plastic PA liners are widely used in the manufacturing industry in the production of food and beverage containers. We covered the aluminum boss with a plastic liner material and wound the composite fibers over the liner material. To reinforce the dome area, we used low strength / high elongation plastic liner. To predict the performance of the developed product, we conducted structural analyses utilizing the 3D laminated solid element. We verified the soundness of the product by testing the prototype.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.50-50
• /
• 2009

본 연구에서는 차체 부품의 경량소재 대체에 따른 Panel Assembly Rear Seat Back 부품 제작에 최신 저입열 미그용접공정을 적용한 TWB(Tailor Welded Blank) 공정기술을 확보하기 위해 최적 용접조건 도출에 관한 연구를 진행하였다. 용접 후 성형이 이뤄지는 제조공정의 특성 상 성형강도에 중점을 둔 실험을 진행하였으며, 이를 위해 각 와이어에 따른 용접부의 기계/금속학적 특성이 평가되었다. 대상 시편은 6천계열 열처리형 합금이며, 두께는 각각 1.6t, 1.4t로 이를 맞대기 용접 후 그 특성을 평가하였다. 용접은 저입열 GMA용접 공법 중 하나인 CMT 용접법(Cold Metal Transfer)을 사용하였으며, 평가 대상 와이어로는 4043, 4047, 5183 및 5356이 사용되었다. 특성평가는 마크로 및 마이크로 조직, 경도, 인장강도, 기공 및 결함, 성형강도 등에 대해 이뤄졌으며, 희석된 와이어의 조성이 용접부 특성에 미치는 영향에 대해서도 검토되었다. 실험 결과, 5천계열 와이어가 성형강도에 비교적 더 강인한 결과를 나타냈으며 성형강도는 용접조건 및 초기 갭에 대한 영향은 받았으나, 비드형상과 강도간의 연관성은 찾을 수 없었다. 이에 따라 TWB 적용을 위한 와이어로는 5356이 가장 우수한 것으로 판명되었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2009.06a
• /
• pp.27-27
• /
• 2009

Non-stochiometric CdS:H films grown on polyethersulfon (PES) flexible polymer substrates at room temperature by R.F. sputtering technique. They exhibited a dark- and photo-sheet resistance of $2.7\times10^5$ and $\sim\;50\;{\Omega}$/square, respectively. These values were realized by an optimum control of both hydrogen doping-levels and the surface morphologies of the films. The comparison between the real and the simulated results for the shielding and the transmission by the free space measurement system in the X-band frequency range (8.2 - 12.4 GHz) was also addressed in this study. Samples overlapped with 13 layers of CdS:H/PES were consistent with the transmission results of pure aluminum metal films ($0.1\;{\Omega}$/square) deposited on PES substrates. As a result, by the simples tacking of the CdS:H/PES layers, the perfect control of the shielding and the transmission of the EM wave in the range of X-band frequency is possible by avisible light alone, and their results are especially very outstanding findings in the stealth function of the radome(Radar+Dome) such as aircrafts, ships, and missiles.

• 대한공업교육학회지
• /
• v.35 no.2
• /
• pp.224-237
• /
• 2010

When the underwater structure sails high speed, noise and vibration propagate to the sensor in the nose of the dome. In this paper, to avoid this kind of noise and vibration CRP(Carbon Reinforced Plastic) material and SNORE ring(Self-NOise REduction Ring) are attached at the curved structure and simulates its isolation characteristics using commercial software. Vibration displacement and stress are calculated at the planar sensor array. The material of the curved structure is aluminum and maximum outer diameter is 53Omm, 215mm in length, 270mm in planar diameter, respectively. Based on the simulation results, reduction ratio of the received normal stress at the sensor is above 95% at the frequency of 12kHz and 15kHz. At the mid point of the planar sensor the normal stress is higher than 20mm and 40mm apart. This results can be used to increase the sensitivity of the acoustic sensor as a basic data.

• Journal of the Korean Institute of Gas
• /
• v.13 no.6
• /
• pp.29-33
• /
• 2009

In this study, the strength safety of a composite fuel tank which is fabricated by an aluminum liner of Al6061-T6 materials and composite layers of carbon/epoxy-glass/epoxy composites has been analyzed by using a finite element analysis technique. In order to enhance the durability of the composite fuel tank, an autofrettage process was used and compressed natural gas was supplied to the prestressed fuel tank. The FEM computed results on the stress safety of autofrettaged gas tanks were compared with a criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results indicated that the stress safety of autofrettaged fuels tanks shows instability at the dome zone and uniform stability at the parallel body, which provide an evaluation data for a strength safety of autofrettaged composite fuel tanks. The computed results show that the stress safety of 9.2 liter composite fuel tanks satisfied the safety criteria of four evaluation items, which are provided by US DOT-CFFC and KS and indicated a safe design.