• Transactions of Materials Processing
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• v.15 no.4 s.85
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• pp.319-325
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• 2006

The laser forming process is a new flexible forming process without forming tools and external force, which is applied to various fields of industry. Especially, applications of the laser forming process focused on cutting, welding and marking process. In this paper, the laser bending process of sheet metal which is heated by laser beam and formed by internal stress is simulated by using thermo elastic-plastic analysis model. Based on the result of FE-analysis, the laser bending machine is made to obtain reliable data for sheet bending. Under the same condition as FE-analysis, the laser bending experiment has been performed to ver 펴 the result of FE-analysis and good agreement has been obtained between FE-analysis and experiments. Additional laser bending experiments have been performed to evaluate the laser bending machine.

• Transactions of Materials Processing
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• v.14 no.2 s.74
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• pp.160-167
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• 2005

In the present study about extru-bending of angle product, the bending of extruded angle products with the $'\Lambda'$ section and 'ㄱ', section can be obtained using two extrusion billets by the hot metal extru-bending machine with the two punches moving in the different velocity. The bending curvature can be controlled by the different velocity of billets through the two-hole container. This paper describes simulations and experiments of extru-bending process that can make bending during extruding by the difference of stem velocities. And they are applied to two kinds of dies, that is, one of them is conical dies with symmetry $'\Lambda'$ section and the other one is conical dies with asymmetry 'ㄱ' section. The results of the forming simulation by $DEFORM^{TM}-3D$ and results of experiments show that the bending phenomenon at the die exit during extrusion can be obtained with two extrusion billet by the two stems moving in the different velocity. And it was known that it is possible to design the structure of conical cavity of extrusion dies and to control the curvature of product through the simulation and experiment of extru-bending process.

• Transactions of Materials Processing
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• v.13 no.8
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• pp.663-670
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• 2004

The bending phenomenon has been known to be occurred by the difference of velocity at the die exit. The difference of velocity at the die exit section can be obtained by the different velocity of billets through the multi-hole container. The difference of velocity at the die exit can be controlled by the two variables, the one of them is the different velocity of extrusion punch through the multi-hole container, the other is the difference of hole diameter of muliti-hole container. In this paper the difference of hole diameter is applied. So it can bend during extruding products because of the different amount of two billets when billets would be bonded in the porthole dies cavity. And the bending curvature can be controlled by the size of holes. The experiments with aluminum material for the curved tube product had been done for circular or rectangular curved tube section. The results of the experiments show that the curved tube product can be formed by the extru-bending process without the defects such as distortion of section and thickness change of wall of tube and folding and wrinkling. The curvature of product can be controlled by shape of cross section and the difference of billet diameters. And it is known that the bonding and extruding and bending process can be done simultaneously in the die cavity by the experiments that rectangular hollow curved tubes could be extruded by porthole dies with four different size billets made of aluminum material. And it shows that bending phenomenon can happen during extruding with for different billets from the analysis by DEFORM-3D.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1078-1084
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• 2011

In design of sport footwear, bending stiffness of its toe part is an important factor though it can be hardly measured. This paper introduces a device for measuring the bending stiffness. The device is simply designed with aluminum frames, one AC motor, two load-cells, one encoder and control hardwares. The mechanism measuring the bending moment of a shoe is described. Then, it was used to observe how the midsole material and design of a sports shoe affect on its bending stiffness. For the experiments, various specimens prepared, where each midsole of the specimens is different in terms of material, thickness and hardness. With those specimens, experiments were performed by using the device and then the bending stiffness was computed by applying the least square curve fitting after the bending moment data were measured. The specimen with Poly-urethane(PU) midsole has the higher bending stiffness than the one with Phylon(PH) midsole, and the midsole thickness affects more on the bending stiffness than the midsole hardness. Based on those results, it can be concluded that the measurement device can provide consistent bending stiffness data to sports footwear and the bending stiffness of a footwear measured by the developed device can be used as a major parameter in the footwear design.

• Journal of Welding and Joining
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• v.25 no.1
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• pp.37-41
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• 2007

The purpose of this study is to establish the predictive method of angular distortion of the double-sided multi-pass butt weldment achieve it, the behavior of angular distortion in the butt weldment were investigated using comprehensive finite element analyses and experiments. The angular distortion in the multi-pass butt weldment strongly depends on the welding heat input(Q) and the effective bending rigidity of the weld throat. The effective bending rigidity of the first welding pass on the backing side was defined as the function of dimensionless parameter(k) and a bending rigidity of bead-on-plate weldment. Based on the results, the predictive equation for angular distortion of multi-pass butt weldment was proposed and verified by experiments.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.15-16
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• 2016

The roof-top of deteriorated building is necessary to improve that performance of waterproof and heat insulation is lowered. However, the existing method is difficult to supply due to complicated process and high cost. Therefore, practical condition and demand for occupant considered, it is necessary to develop inexpensive and easy method, such as a floating floor method using thermal insulation. This study is experiments on foundational experiment was conducted on the bending strength. A polyurethane board for experiment forms a square and it has various size that 25cm, 33cm, 50cm, and 100cm. Meanwhile, the uniform load of 200kg/㎡ which general working load is applied to the bending strength.

• Structural Engineering and Mechanics
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• v.42 no.6
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• pp.883-897
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• 2012

Cold-formed channel sections are used in a variety of applications in which they are required to absorb deformation energy. This paper investigates the collapse behaviour and energy absorption capability of cold-formed steel channels with flange edge stiffeners under large deformation major-axis bending. The Yield Line Mechanism technique is applied using the energy method, and based upon measured spatial plastic collapse mechanisms from experiments. Analytical solutions for the collapse curve and in-plane rotation capacity are developed, and used to model the large deformation behaviour and energy absorption. The analytical results are shown to compare well with experimental values. Due to the complexities of the yield line model of the collapse mechanism, a simplified procedure to calculate the energy absorbed by channel sections under large bending deformation is developed and also shown to compare well with the experiments.

• Journal of Mechanical Science and Technology
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• v.20 no.2
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• pp.234-241
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• 2006

A functional external fixator system for bone deformity near the joints using worm gear was developed for curing the angle difference in fracture bones while the lengthening bar was developed for curing the differences in length, also in fracture bones. Both experiments and FE analysis were performed to compare the elastic stiffness in several loading modes and to improve the functional external fixator system for bone deformity near joints. The FE model using compressive and bending FE analysis was applied due to the angle differentiations. The results indicate that compressive stiffness value in the experiment was 175.43N/mm, bending stiffness value in the experiment was 259.74 N/mm, compressive stiffness value in the FEA was 188.67 N/mm, and bending stiffness value in the FEA was 285.71 N/mm. Errors between experiments and FEA were less than $10\%$ in both the 'compressive stiffness and the bending stiffness. The maximum stress (157 MPa) applied to the angle of the clamp was lower than the yield stress (176.4 MPa) of SUS316L. The degree of stiffness in both axial compression and bending of the new fixator are about 2 times greater than other products, with the exception of EBI (2003).

• Transactions of Materials Processing
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• v.10 no.4
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• pp.329-337
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• 2001

The finite element simulation model and the program to calculate the reverse moment have been developed to analyse the stress state and deformation of pipe bending using local induction heating with small bending radius in this study. The reverse moment that is to be applied on the bending arm to control the wall thinning ratio of the bending outside to within a particular value. Even though the demand of pipes with small bending radius is increasing in power plants and ship buildings, the welded elbows are still widely used. The bending process with or without a reverse moment acting on the bending arm has been simulated. The reverse moments calculated from the developed program are in good agreement with the finite element simulations and the experiments.

• Structural Engineering and Mechanics
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• v.7 no.5
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• pp.457-471
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• 1999

In this paper, different curvature-rates are controlled to highlight the characteristic of viscoplastic response in cyclic bending tests. The curvature-ovalization apparatus, which was designed by Pan et al. (1998), is used for conducting the curvature-controlled experiments on thin-walled tubular specimens for AISI 304 stainless steel under cyclic bending. The results reveals that the faster the curvature-rate implies, the fast degree of hardening of the metal tube. However, the ovalization of the tube cross-section increases when the curvature-rate increases.