• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.169-176
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• 2018

Removal of angular deformation induced during the welding of butt joints in thick steel plates needs expert skill and is costly. To reduce deformation, proper joint designs are studied with a prediction of deformation prior to welding. However, as the thickness of a plate increases, a predictive analysis of the welding process is more difficult, especially if there is an increase in the number of welding passes in the joint. In this study, a numerical model with the finite element method (FEM) was developed to analyze the angular deformation in the multi-pass welding of butt joints of plates made of AH32 steel that had a thickness of up to 100 mm. A series of numerical simulations were then performed based on the developed model to predict the deformations for thick plates. With the results obtained by the analyses, this study suggested optimal X-shape grooves for the butt joints of thick plates to minimize the angular deformation. As the thickness of the plate increased to 100 mm, the ratio of the depth of the front-side groove to that of the back-side groove should be gradually increased to nearly 1:3.

• Journal of Fashion Business
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• v.20 no.3
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• pp.17-29
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• 2016

To develop baseball catcher leg guards, 3-dimensional (3D) methodologies, which are 3D human body data, reverse engineering, modeling, and printing, optimized guard design for representative positions. Optimization was based on analysis of 3D body surface data and subjective evaluation using 3D printing products. Reverse engineering was used for analysis and modeling based on data in three postures: standing, $90^{\circ}$ knee flexion, and $120^{\circ}$ knee flexion. During knee flexion, vertical skin length increased, with the thigh and knee larger in anterior area compared to the horizontal dimension. Moreover, $120^{\circ}$ knee flexion posture had a high radius of curvature in knee movement. Therefore, guard designs were based on increasing rates of skin deformation and numerical values of radius of curvature. Guards were designed with 3-part zoning at the thigh, knee, and shin. Guards 1 and 2 had thigh and knee boundaries allowing vertical skin length deformation because the shape of thigh and knee significantly affects to its performance. Guard 2 was designed with a narrower thigh and wider knee area than guard 1. The guards were manufactured as full-scale products on a 3D printer. Both guards fit better in sitting than standing position, and guard 2 received better evaluations than guard 1. Additional modifications were made and an optimized version (guard 3) was tested. Guard 3 showed the best fit. A design approach based on 3D data effectively determines best fitting leg guards, and 3D printing technology can customize guard design through immediate feedback from a customer.

• International Journal of CAD/CAM
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• v.8 no.1
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• pp.63-67
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• 2009

This paper puts forward a method based on the boundary deformation for planar grid generation. Many methods start with the special properties of grid and switch to the solution of a direct optimization or a non-linear minimum cost flow. Though with high theoretical significance, it's hard to realize due to the extremely complicated computing process. This paper brings out the automatic generation of planar grid by studying the boundary deformational properties of planar grid, which leads to uniform grid and enjoys the simplicity of computation and realization.

• Journal of Adhesion and Interface
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• v.5 no.2
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• pp.14-26
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• 2004

For reliable determination of mechanical characteristics of adhesively bonded joints used e.g. as input data for computer-aided design of complex components, the thick-adherend tensile-shear test according to ISO 11003-2 is the most important material testing method. Although the total displacement of the joint is measured across the polymer layer directly in the overlap zone in order to minimize the influence of the stepped adherends, the substrate deformation must be taken into account within the framework of the evaluation of the shear modulus and the maximum shear strain, at least when high-strength adhesives are applied. In the standard ISO 11003-2 version of 1993, it was prescribed to perform the substrate deformation correction by means of testing a one-piece reference specimen. The authors, however, pointed to the excessive demands on the measuring accuracy of the extensometers connected with this technique in industrial practice and alternatively proposed a numerical deformation analysis of a dummy specimen. This idea of a mathematical correction was included in the revised ISO 11003-2 version of 2001 but in the simplified form of an analytical method based on Hooke's law of elasticity for small strains. In the present work, it is shown that both calculation techniques yield considerably discordant results. As experimental assessment would require high-precision distance determination (e.g. laser extensometer), finite element analyses of the deformation behavior of the bonded joint are performed in order to estimate the accuracy of the obtained substrate deformation corrections. These simulations reveal that the numerical correction technique based on the finite element deformation modeling of the reference specimen leads to considerably more realistic results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1960-1965
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• 2001

In the practical design, it is important to extract the design space information of a complex system in order to optimize the design because the design contains huge amount of design conflicts in general. In this research FEA (finite element analysis) has been successfully implemented and integrated with a statistical approach such as DOE (design of experiments) based RSM (response surface model) to optimize the thermal deformation of an automotive disk brake. The DOE is used for exploring the engineer's design space and for building the RSM in order to facilitate the effective solution of multi-objective optimization problems. The RSM is utilized as an efficient means to rapidly model the trade-off among many conflicting goals existed in the FEA applications. To reduce the computational burden associated with the FEA, the second-order regression models are generated to derive the objective functions and constraints. In this approach, the multiple objective functions and constraints represented by RSM are solved using the sequential quadratic programming to archive the optimal design of disk brake.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.106-113
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• 2004

The eddy current brake system is a non-contact brake based on the mutual relation between the rail and the frame. Consequently, the accuracy is required in estimating the stress concentration and the deformation of the eddy current brake system. In this paper, the static analysis considering the gravity and the suction force for the deformation and the stress concentration of the main frame of the initially designed eddy current brake system was carried out. The shape of the I-type beam obtained from the optimization was analyzed and compared with the initial model. Also, the initial model was modified based on the optimization model and the result was verified to have the acceptable improvement.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.6
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• pp.1-12
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• 2012

The researches related to active control systems utilizing superelastic shape memory alloys (SMA) have been recently conducted to reduce critical damage due to lateral deformation after severe earthquakes. Although Superelastic SMAs undergo considerable inelastic deformation, they can return to original conditions without heat treatment only after stress removal. We can expect the mitigation of residual deformation owing to inherent recentering characteristics when these smart materials are installed at the part where large deformation is likely to occur. Therefore, the primary purpose of this research is to develop concentrically braced frames (CBFs) with superelastic SMA bracing systems and to evaluate the seismic performance of such frame structures. In order to investigate the inter-story drift response of CBF structures, 3- and 6-story buildings were design according to current design specifications, and then nonlinear time-history analyses were performed on numerical 2D frame models. Based on the numerical analysis results, it can be comparatively verified that the CBFs with superelastic SMA bracing systems have more structural advantages in terms of energy dissipation and recentering behavior than those with conventional steel bracing systems.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.113-123
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• 2006

An experimental investigation on the behavior of reinforced concrete coupling beams is presented. The test variables are the span-to-depth ratio, the ratio of flexural reinforcements and the ratio of shear rebars. The distribution of arch action and truss action which compose the mechanism of shear resistance is discussed. The increase of plastic deformation after yielding transforms the shear transfer by arch action into by truss action. This study proposes the deformation model for reinforced concrete coupling beams considering the bond slip of flexural reinforcement. The strain distribution model of shear reinforcements and flexural reinforcements based on test results is presented. The yielding of flexural reinforcements determines yielding states and the ultimate states of reinforced concrete coupling beam are defined as the ultimate compressive strain of struts and the degradation of compressive strength due to principal tensile strain of struts. The flexural-shear failure mechanism determines the ultimate state of RC coupling beams. It is expected that this model can be applied to displacement-based design methods.

• Transactions of Materials Processing
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• v.12 no.1
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• pp.43-48
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• 2003

The strain state during the continuous confined strip shearing (CCSS) based on ECAP was tackled by means of a two-dimensional FEM analysis. The deformation of AA 1100 sheet in the CCSS apparatus was composed of three distinct processes of rolling, bending and shearing. The pronounced difference in the friction conditions on the upper and lower roll surfaces led to the different variation of the strain component ${epsilon}_13$ throughout the thickness of the aluminum sheet. Strain accompanying bending was negligible because of a large radius of curvature. The shear deformation was concentrated at the corner of the CCSSchannel where the abrupt change in the direction of material flow occurred. The process variables involving the CCSS-die design and frictions between tools and strip influenced the evolution of shear strains during CCSS.

• Geomechanics and Engineering
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• v.20 no.2
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• pp.121-129
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• 2020

In the design of geotechnical structures, engineers choose either peak or critical state friction angles. Unfortunately, this selection is based on engineer's preference for economy or safety and lacks the assessment of the expected level of deformation. To fill this gap in the design process, this study proposes a strain based empirical method. Proposed method is founded on the experimentally supported assumption that higher dilatancy angles result in more brittle soil response. Using numerous triaxial test data on ten different soils, an empirical design chart is developed that allows the estimation of shear strain at failure based on soil's peak dilatancy angle and mean grain diameter. Developed empirical chart is verified by conducting a small scale retaining wall physical model test. Finally, a design methodology is proposed that makes the selection of design friction angle in structured way possible based on the serviceability limits of the proposed structure.