• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.152-155
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• 2003

In order to examine the springback of aluminum alloy sheets, AL1050 and AL5052, in the warm forming which forms the sheet above room temperature, the stretch bending and draw bending tests in various working temperatures were carried out. While the springbacks of AL5052 and AL1050 are tremendously reduced over 150$^{\circ}C$ in the stretch bending test, the springbacks in the draw bending test are rapidly reduced in 150$^{\circ}C$-200$^{\circ}C$ for AL5052 and 200$^{\circ}C$-250$^{\circ}C$ for AL1050. Using the FEM program, the forming and springback processes are analyzed. Though springback amounts of analysis result are slightly bigger than those of experiment, they showed the same trend in the decreasing springback as the forming temperature increases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.5
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• pp.567-576
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• 2023

In general, RC beam members are designed as flexural members, considering only the bending load. However, in actual buildings, axial and bending load are simultaneously applied due to the continuity between members. As a result, the bending strength of the RC beam member increases, but the displacement decreases, and cracks are mainly concentrated in the center of the beam. Therefore, in this study, the bending performance of both normal and strengthened RC beam using carbon fiber sheets subjected to combined axial and bending load was experimentally evaluated. The carbon fiber sheets were wrapped around the middle of the specimens, and axial and bending load were applied simultaneously to the beams. The magnitude of the axial force and the effects of carbon fiber sheet reinforcement on the deformed shape, bending strength, deflection, and ductility of the RC beams were analyzed. The results show that as the applied axial force increased, the maximum bending strength increased, but the ductility decreased 64%. The bending strength of the strengthened beams increased up to 27%, the maximum deflection decreased around 8% and the ductility increased by up to 43%.

• Transactions of Materials Processing
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• v.7 no.3
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• pp.246-259
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• 1998

This paper describes a research work of developing a computer-aided design and manufacturing of irregular shaped sheet metal product for blanking or piercing and bending operations. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated from plasticity theories experimental results and the empirical knowledge of field experts, This system has been written in AutoLISp on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules which are input and shape treatment, flat pattern-layout, pro-processor module. Based on the knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product complexities of blank geometry and punch profile sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacturer of blanking or piercing and bending die in this field.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1998.03a
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• pp.155-159
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• 1998

This paper describes a research work of developing a computer-aided design and manufacturing (CAD-CAM) of irregular shaped sheet metal product for blanking or piercing and bending operation. An approach to the system is based on the knowledge-based rules. Knowledge for the system is formulated form plasticity theories, experimental results and the empirical knowledge of field experts. This system has been written in AutoLIST on the AutoCAD and in customer tool kit on the SmartCAM with a personal computer and is composed of nine modules. the system is designed by considering several factors, such as material and thickness of product, complexities of blank geometry and punch profile, diameter and material of a wire, and availability of press. This system is capable of unfolding a formed sheet metal to give flat pattern and automatically account for the adjustment of bending allowances to match tooling requirements by checking dimensions and generating NC data automatically according to drawings of die-layout module. Results carried out in each module will provide efficiencies to the designer and the manufacture of blanking or piercing and bending die in this field.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.990-996
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• 2008

Nowadays, the trend to a lightweight design accelerates the use of advanced high strength steel (AHSS) in automotive industry. Springback phenomena is a hot issue in the sheet metal forming, especially bending process using AHSS. Several analytical methods for that have been proposed in recent years. Each of method has their advantages and disadvantages. There are only a few optimal solutions which can minimize the two objectives simultaneously. In this study, an effective method optimized the multi objective value. The method by the design of experiments(DOE) and artificial neural network(ANN) was presented to compensate springback of bending parts. This method was applied to L and V bending process. The effective method could be optimized to multiple object. It was confirmed that the proposed method was more efficient than traditional manual FEA procedure and the trial and error approach for springback compensation.

• Steel and Composite Structures
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• v.21 no.5
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• pp.1145-1156
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• 2016

To study the effects of foam core density and face-sheet thickness on the mechanical properties and failure modes of aluminum foam sandwich (AFS) beam, especially when the aluminum foam core is made in aluminum alloy and the face sheet thickness is less than 1.5 mm, three-point bending tests were investigated experimentally by using WDW-50E electronic universal tensile testing machine. Load-displacement curves were recorded to understand the mechanical response and photographs were taken to capture the deformation process of the composite structures. Results demonstrated that when foam core was combined with face-sheet thickness of 0.8 mm, its carrying capacity improved with the increase of core density. But when the thickness of face-sheet increased from 0.8 mm to 1.2 mm, result was opposite. For AFS with the same core density, their carrying capacity increased with the face-sheet thickness, but failure modes of thin face-sheet AFS were completely different from the thick face-sheet AFS. There were three failure modes in the present research: yield damage of both core and bottom face-sheet (Failure mode I), yield damage of foam core (Failure mode II), debonding between the adhesive interface (Failure mode III).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.18-21
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• 1999

In this study in order to make doubly-curved sheet metal effectively a sheet metal forming process has been developed by adopting the flexibility of the incremental forming process and the principle of bending deformation which causes slight deformation to thickness The developed process is an unconstrained forming process with no holder. For this study the experimental equipment is set up with the punch-set which consists of two pairs of lower support-punches and one upper center-punch. In the experiments using aluminum sheet it is found that the curvature of the formed sheet metal is determined by controlling the distance between supporting punches in pairs and the forming depth of the center-punch. and the edge-forming method is proposed for forming the sheet metal into the balanced shape. The equation using process variables such as the distance between supporting punches in pairs and the forming depth of the center-punch is proposed for the prediction of the radii of curvatures of the formed shape and it is corrected by the experimental results and the FEM simulation results about whether springback takes place. It is found that according o the simulation there is a certain set of the distance between a pair of supporting punches and the forming depth of the center-punch which causes a little springback. It is thus shown that the radii of curvatures of the formed sheet metal can be predicated by the corrected equation unless significant springback occurs.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.289-293
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• 2007

The effect of temperature on the forming limit diagram was investigated for AZ31B magnesium alloy sheet through the limit dome height test in the range from room temperature to $300^{\circ}C$. The formability of AZ31B sheet was improved significantly according to the increasing temperature. Also we studied the springback characteristics through the 2D draw bending test with different blank holding forces at elevated temperatures. Springback quantity was considerably reduced as temperature went up. The blank holding force in the range used, however, had little influence on springback. Experimental results obtained in this study may provide a material database for AZ31B sheet.

• Proceedings of the Korean Geotechical Society Conference
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• 1994.09a
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• pp.1-59
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• 1994

The design and construction of strutted and anchored sheet pile walls in soft clay are reviewed based on experience gained mainly in Singapore during the last 10years where mainly strutted sheet pile walls diaphragm walls, and contiguous bored piles are used. It is important to consider in the design the high lateral earth pressures acting on the sheet piles below the bottom of the excavation when the depth of the excavation is large compared with the shear strength of the clay. The strut loads and the maximum bending moment in the sheet piles can in that case be much higher than indicated by a conventional analysis. Different methods to increase the stability have been investigated. With jet grouting, embankment piles and excavation under water it is possible to reduce significantly the maximum bending moment, the strut loads, and the settlements outside the excavated area as well as the heave within the excavation.

• Transactions of Materials Processing
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• v.16 no.5 s.95
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• pp.364-369
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• 2007

The effect of temperature on the forming limit diagram was investigated for AZ31B magnesium alloy sheet through the limit dome height test in the range from room temperature to $300^{\circ}C$. The formability of AZ31B sheet was improved significantly according to the increasing temperature. Also we studied the springback characteristics through the 2D draw bending test with different blank holding forces at elevated temperatures. Springback quantity was considerably reduced as temperature went up. The blank holding force in the range used, however, had little influence on springback. Experimental results obtained in this study may provide a material database for AZ31B sheet.