• Transactions of Materials Processing
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• v.25 no.1
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• pp.29-35
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• 2016

In the current study, finite element analysis was conducted for the press hemming of automotive panels in order to predict various hemming defects such as roll-in and turn down. The analysis used the exact punch movement based on the cam location and considered the sealer between the inner and outer panels with an artificial contact thickness. The analysis results quantify the hemming defects especially at the flange edge in the matching region of the head lamp. A design of experiments along with the parameter study was used to obtain the optimum process parameters for minimizing hemming defects. The optimization process selects the intake angle, bending angle of the hemming punch, and the flange height of the outer panel. The optimum design process determines an appropriate tool angle and flange height to reduce the roll-in and turn-down as compared to the initial design.

• Transactions of Materials Processing
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• v.8 no.1
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• pp.7-13
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• 1999

In this study, side panels were developed using the laser-welded tailored blank (T.B.) of both the same thickness and different thickness. At first, the formability of the same thickness T.B. was investigated to compare with one of the non-welded panel with respect to weldline movement and strain distribution in blank during the stamping process. Based on these results, we determined the weld line positions and the die step for T.B. forming of the blanks composed of different thickness combination. Then we made some stamping tryouts with selected types of blanks to investigate the formability of T.B. of the different thickness. During the tryouts, wrinkles were found in the a-pillar lower region which is under the deformation mode of the shrink flange. In the b-pillar region, fractures were also found. These defects have been reduced and corrected by controlling the blank design, the die faces and process parameters.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.253-258
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• 2000

Recently, the area of design optimization, especially structural optimization, has been and to be a continuous active area of research. And the design optimizations of port facilities have been achieved by many other civil engineers. But the design optimization of port facilities were limited to the design optimization of the breasting dolphin. This paper invested the design optimization of mooring pier and the foundations of mooring pier was suggested considering the convenience of repair and reinforcement work. The mooring pier devised with prestressed precast concrete panel and rigid frame welded wide flange beam to steel pipe pile. To accomplish the design optimization of mooring pier, the Augmented Lagrangian Multiplier Method(ALM) of ADS(Garret N. Vanderplaats) optimization routine, BFGS method as optimizer and Golden Section Method as one dimensional search were utilized. As a result, thirty percent of material cost for construction was reduced by design optimization. The tensile stress of concrete panel and bottom flage was critical constraints under service load. So, using high strength concrete and steel will be economical. And lots of initial values must be invested to accomplish the design optimization in design procedures.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.164-167
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• 2004

The draw, trim, flange, and cam forming processes of automotive fender panel are simulated, focused on the springbacks. Simulation results are compared with field try-out. In order to compensate the differences between simulation and try-out, the draw bead shapes in the simulation are modified and the accuracy of the simulation is improved by comparing blank draw-in amounts. The spring-backs after formings are also found in the simulation. Finally, the simulation procedures for analyzing the springbacks in all stamping processes are established.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.06a
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• pp.102-109
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• 1998

In this study, the side panels were developed using the laser-welded Tailored Blanks (TB) with both the same thickness and the different thickness. At first, the formability of the same thickness T.B was investigated to be compared with one of the non welded panel with respect to weldline movements and strain distribution on blank during the stamping. Based on these results, we selected candidates of T.B with different thickness for stamping experiments. That is, we determined the weld line positions and the die step. Then we made some stamping tryouts with selected types of blank designs to investigate the formability of T.B with different thickness. During the tryouts, the wrinkles were found in the a-pillar lower region which is under the deformation mode of the shrink flange. In the b-pillar region, the fractures were found also, these defects have been reduced and corrected by controlling the blank design and the die faces and process pamameters.

• Steel and Composite Structures
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• v.43 no.3
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• pp.327-340
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• 2022

A vast amount of experimental and analytical research has been conducted related to the seismic behavior and performance of concrete filled steel tubular (CFT) columns. This research has resulted in a wealth of information on the component behavior. However, analytical and experimental data for structural systems with CFT columns is limited, and the well-known behavior of steel or concrete structures is assumed valid for designing these systems. This paper presents the development of an analytical model for nonlinear analysis of composite moment resisting frame (CFT-MRF) systems with CFT columns and steel wide-flange (WF) beams under seismic loading. The model integrates component models for steel WF beams, CFT columns, connections between CFT columns and WF beams, and CFT panel zones. These component models account for nonlinear behavior due to steel yielding and local buckling in the beams and columns, concrete cracking and crushing in the columns, and yielding of panel zones and connections. Component tests were used to validate the component models. The model for a CFT-MRF considers second order geometric effects from the gravity load bearing system using a lean-on column. The experimental results from the testing of a four-story CFT-MRF test structure are used as a benchmark to validate the modeling procedure. An analytical model of the test structure was created using the modeling procedure and imposed-displacement analyses were used to reproduce the tests with the analytical model of the test structure. Good agreement was found at the global and local level. The model reproduced reasonably well the story shear-story drift response as well as the column, beam and connection moment-rotation response, but overpredicted the inelastic deformation of the panel zone.

• Journal of the Korean Society for Advanced Composite Structures
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• v.4 no.3
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• pp.30-37
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• 2013

It is same such as the provision of shear buckling strength of steel composite box girder web panel and plate girder web panel in Korea Highway Bridge Design Standards(2012). But the web panel of steel composite box girder is different from the web of plate girder in that the upper slab and lower flange are connected to the web. So a different shear behavior of the girders is expected. In this study, To calculate a reasonable elastic shear buckling strength of steel composite box girder web panel, ABAQUS program was used. The results from F.E.A and previous studies are compared. It is shown that the web shear buckling strength of steel composite box girder of Korea Highway Bridge Design Standards(2012) is the most conservative.

• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.3
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• pp.69-77
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• 2003

This paper presents test results on eight reduced beam section(RBS) steel moment connections. The testing program addressed bolted versus welded web connection and panel zone(PZ) strength as key variables, Specimens with medium PZ strength were designed to promote energy dissipation from both PZ and RBS regions such that the requirement for expensive doublet plates could be reduced. Both strong and medium PZ specimens with a welded web connection were able to provide satisfactory connection rotation capacity for special moment-resisting frames. On the other hand, specimens with a bolted web connection performed poorly due to premature brittle fracture of the beam flange of the weld access hole. If fracture within the beam flange groove weld was avoided using quality welding, the fracture tended to move into the beam flange base metal of the weld access hole. Plausible explanation of a higher incidence of base metal fracture in bolted web specimens was presented. The measured strain data confirmed that the classical beam theory dose not provide reliable shear transfer prediction in the connection. The practice of providing web bolts uniformly along the beam depth was brought into question. Criteria for a balanced PZ strength improves the plastic rotation capacity while reduces the amount of beam distortion ore also proposed.

• Composites Research
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• v.30 no.6
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• pp.384-392
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• 2017

Sandwich panels with three different joint configurations were tested to design a novel sandwich joint structure that can effectively support both the tensile and compressive loads. The sandwich core was mainly aluminum flex honeycomb but the PMI foam core was limitedly applied to the ramp area which is transition part from sandwich to solid laminate. The face of sandwich panel was made of carbon fiber composite. For configuration 1, the composite flange and the sandwich panel were cocured. For configurations 2 and 3, an aluminum flange was fastened to the solid laminate by HI-LOK pins and adhesive. The average compressive failure loads of configurations 1, 2, and 3 were 295, 226, and 291 kN, respectively, and the average tensile failure loads were 47.3 (delamination), 83.7 (bolt failure), and 291 (fixture damage) kN, respectively. Considering the compressive failure loads only, both the configurations 1 and 3 showed good performance. However, the configuration 1 showed delamination in the corner of the composite flange under tension at early stage of loading. Therefore, it was confirmed that the structure that can effectively support tension and compressive loads at the same time is the configuration 3 which used a mechanically fastened aluminum flange so that there is no risk of delamination at the corner.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2001.10a
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• pp.227-234
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• 2001

The lifting and lowering supports method was recently developed in steel box girder bridge. It has many advantages by lifting and lowering of inner supports and filled concrete. This method reduces an amount of steel and height of girders. It is one of the methods used to effectively increase the use of structural material. However, if there is too much lifting of inner supports, it is possible to cause buckling of the compression flange or web panel. Therefore it needs a proper number of longitudinal and transvers stiffener.