• Transactions of Materials Processing
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• v.14 no.7 s.79
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• pp.613-618
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• 2005

The paper is concerned with the process design and the die design for manufacturing the preform of a large pressure vessel. The cold-working processes are introduced to improve the fatigue strength and to simplify the manufacturing process. By the finite element simulation, the parameter design is carried out, which is subjected to constraints such as the blank sire, press capacity and other minor limitations. The proposed design results are verified by the model experiments, in which the model is scaled down to one tenth of the original size.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.10a
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• pp.390-395
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• 2003

Moving flexible structures such as transfer systems in press machine, crane, working table of machine tools have vibration problems because of starting, feeding and stopping. An analysis method is suggested and experimentally studied in order to solve a vibration problem of a moving flexible structure. In this method, the concepts of substructure synthesis method and semi-static displacement including rigid body mode were used. Total deformation of a structure was assumed to be composed of quasi-static and dynamic components. Experimental results from an elementary model of a transfer feeder showed good agreements with computational results.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.52-57
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• 2020

The frequency of the manufacturing and modification of automotive press dies via overlay welding has recently increased, but the welding quality depends on the operator skills and the working conditions. Therefore, this study presents a way to improve the overlay welding quality regardless of the operator skills. Three welding conditions with different pre- and post-heating treatments were tested on some specimens; the weld surface quality was analyzed by examining the cutting face. The results demonstrated the best quality of the weld surface that was heated before and after the welding.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1998.10a
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• pp.267.2-272
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• 1998

The fine blanking is a process of press-working which makes possible to produce thick sheet metal parts of finished sheared surface and close dimensional accuracy over whole material thickness in single blanking operation. Fineblanked parts in general are characterized by their cleanly sheared surface over the whole stock thickness and accurate size for the specific functions. The fine blanking technology is urgently needed to remove secondary operations which are necessary in conventional blanking operation and cost reduction. In this study, the effect of material texture and vee-ring on parts for automobile is investigated by experimental observation and analysis.

• Structural Engineering and Mechanics
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• v.31 no.3
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• pp.315-331
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• 2009

Mechanical connections are recognized as extremely important elements in the aspect of strength and structural safety. However, classical structural model does not consider the connection stiffness properties, and are based on models with pinned or rigid joints only. In fact, mechanical connections are deformable and behave not linearly, affecting the whole structure and inducing nonlinear behavior as well. The quantification of this effect, however, depends on the description of the working of the connectors and the wood response under embedment. The theoretical modeling of wood structures with semi-rigid connections involves not only the structural analysis, but also the modeling of both single and grouped moment resisting connectors and the study of the wood properties under embedment. The proposal of this paper is to approach these aspects, and to quantitatively study the influence of the moment resistant connection in wooden framed structures. Comparisons between rigid and semi-rigid connections and between linear and nonlinear analysis lead to quantitative results.

• Structural Monitoring and Maintenance
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• v.1 no.2
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• pp.213-230
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• 2014

A novel real-time actuator failure detection algorithm is developed in this paper. Actuator fails when the input to the structure is different from the commanded one. Previous research has shown that one error function can be formulated for each actuator through interaction matrix method. For output without noise, non-zero values in the actuator functions indicate the instant failure of the actuator regardless the working status of other actuators. In this paper, it is further demonstrated that the actuator's error function coefficients will be directly calculated from the healthy input of the examined actuator and all outputs. Hence, the need for structural information is no longer needed. This approach is termed as direct method. Experimental results from a NASA eight bay truss show the successful application of the direct method for isolating and identifying the real-time actuator failure. Further, it is shown that the developed method can be used for real-time sensor failure detection.

• Smart Structures and Systems
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• v.4 no.2
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• pp.137-152
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• 2008

The work presented in this paper includes material characterisation and an investigation of suitability in seismic dampers for two commercially available NiTi-alloys, along with a numerical analysis of a new damper system employing composite NiTi-wires. Numerical simulations of the new damper system are conducted, using Brinson's one-dimensional constitutive model for shape memory alloys, with emphasis on the system's energy dissipation capabilities. The two alloys tested showed some unwanted residual strain at temperatures higher than $A_f$, possibly due to stress concentrations near inclusions in the material. These findings show that the alloys are not ideal, but may be employed in a seismic damper if precautions are made. The numerical investigations indicate that using composite NiTi-wires in a seismic damper enhances the energy dissipation capabilities for a wider working temperature range.

• Coupled systems mechanics
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• v.9 no.5
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• pp.397-410
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• 2020

The present investigation is concerned with two-dimensional deformation in a homogeneous isotropic non local thermoelastic solid with two temperatures due to thermomechanical sources. The theory of memory dependent derivatives has been used for the study. The bounding surface is subjected to concentrated and distributed sources (mechanical and thermal sources). The Laplace and Fourier transforms have been used for obtaining the solution to the problem in the transformed domain. The analytical expressions for displacement components, stress components and conductive temperature are obtained in the transformed domain. For obtaining the results in the physical domain, numerical inversion technique has been applied. Numerical simulated results have been depicted graphically for explaining the effects of nonlocal parameter on the components of displacements, stresses and conductive temperature. Some special cases have also been deduced from the present study. The results obtained in the investigation should be useful for new material designers, researchers and physicists working in the field of nonlocal material sciences.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1997.03a
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• pp.281-286
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• 1997

Thin study is concerned with the cold repressing of sintered preform by rotary forging process. A experiment has been carried out using the rotary powder forging press(500kN) which was designed and constructed in the authors' laboratory. The effect of process variables and aspect ratios of sintered preform was observed and measured by several mechanical test, such as working force, hardness distribution, density, and microstructures of the specimens. It is found that the highly densified P/M parts can be obtained and this process is very effective for improving quality of the powder products.

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.3
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• pp.117-130
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• 2014

This paper presents a study on the influence of different thermo-mechanical processing (TMP) parameters on some required properties such as micro-hardness and Young's modulus of a novel near ${\beta}$ alloy Ti-20.6Nb-13.6Zr-0.5V (TNZV). The TMP scheme comprises of hot working above and below ${\beta}$ phase, solutionizing treatment above and below ${\beta}$ phase coupled with different cooling rates. Factorial design of experiment is used to systematically collect data for micro-hardness and Young's modulus. Validity of assumptions related to the collected data is checked through several diagnostic tests. The analysis of variance (ANOVA) is used to determine the significance of the main and interaction effects. Finally, optimization of the TMP process parameters is also done to achieve optimum values of the micro-hardness and Young's modulus.