• Advances in Computational Design
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• v.2 no.4
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• pp.273-281
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• 2017

In this work, a comparative study of multi-objective meta-heuristics (MOMHs) for optimum design of a walking tractor handlebar is conducted in order to reduce the structural mass and increase structural static and dynamic stiffness. The design problem has objective functions as maximising structural natural frequencies, minimising structural mass, bending deflection and torsional deflection with stress constraints. The problem is classified as a many-objective optimisation since there are more than three objectives. Design variables are structural shape and size. Several well established multi-objective optimisers are employed to solve the proposed many-objective optimisation problems of the walking tractor handlebar. The results are compared whereas optimum design solutions of the walking tractor handlebar are illustrated.

• Smart Structures and Systems
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• v.4 no.5
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• pp.549-563
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• 2008

The ability of an electroactive polymer, IPMC (Ionic Polymer Metal Composites,) to produce electric charge under mechanical deformations may be exploited for the development of next generation of energy harvesters. Two different electrode types (gold and platinum) were employed for the experiments. The sample was tested under dynamic conditions, produced through programmed shaking. In order to evaluate the potential of IPMC for dry condition, these samples were treated with ionic liquid. Three modes of mechanical deformations (bending, tension and shear) were analyzed. Experimental results clearly indicate that IPMCs are attractive applicants for energy harvesting, with inherent advantages like flexibility, low cost, negligible maintenance and virtually infinite longevity. Besides, preliminary energy harvesting model of IPMC has been formulated based upon the work of previous investigators (Newbury 2002, Newbury and Leo 2002, Lee, et al. 2005, Konyo, et al. 2004) and the simulation results reciprocate experimental results within acceptable error.

• Advances in aircraft and spacecraft science
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• v.7 no.1
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• pp.19-40
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• 2020

In the present study, a fifth-order shear and normal deformation theory using a polynomial function in the displacement field is developed and employed for the static analysis of laminated composite and sandwich simply supported spherical shells subjected to sinusoidal load. The significant feature of the present theory is that it considers the effect of transverse normal strain in the displacement field which is eliminated in classical, first-order and many higher-order shell theories, while predicting the bending behavior of the shell. The present theory satisfies the zero transverse shear stress conditions at the top and bottom surfaces of the shell. The governing equations and boundary conditions are derived using the principle of virtual work. To solve the governing equations, the Navier solution procedure is employed. The obtained results are compared with Reddy's and Mindlin's theory for the validation of the present theory.

• Transactions of Materials Processing
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• v.7 no.4
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• pp.400-406
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• 1998

The press formability analysis of welding parts was studied in the current work by the tailor welded blank. The press formability was tested by means of the flash weldability and the formability for two kinds of materials (SPCC & S35C). The results indicate that SPCC & S35C steel sheets showed good weldability and formability after an optimum welding conditions. The independent operation variables were characterized by strength of welding parts, deformation after the welding, press formability of welding parts and productibility of welding. The weldability and the quality of welding parts of the flashed SPCC steel sheet was superior to those of the S35C steel sheet, since a higher carbon content in steel sheet led to a higher hardness. The experimental results were discussed by the evaluation of the results obtained from tensile test, hardness test, micro-structure and V bending test.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1068-1071
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• 1996

Good shape on flat rolled product is necessary to meet today's customer quality requirement. To meet the increasing demand in quality of strip shape from downstream customers, POSCO has replaced the Automatic Shape Control(ASC) system with the existing one that had used noncontact type measuring system at No.2 Cold Rolling Mill, Pohang works in October, 1995. The strip shape is influenced by the profile, roll crown, bending control, skew control system, as well as work roll cooling system. We have used ASC to adjust those factors in Cold Rolling Mill that could get a satisfactory result, almost less than .+-.5 1-unit deviation from the target shape. However, the downstream customer(i.e. Continuos Annealing Line) wants a good shape not only at the moment of exit of roll bite, but after rolling without tension. In this investigation, the difference will be discussed and how deal with this problem.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.04a
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• pp.169-176
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• 1999

An improved formulation for spatial stability md free vibration of thin-walled curved beams with variable curvature and non-symmetric cross sections are presented based on the displacement field considering the second order terms of finite semitangential rotations. By introducing Vlasov's assumptions, the total potential energy is derived from the principle of linearized virtual work for a continuum. In this formulation, all displacement parameters and the warping function are defined at the centroid axis so that the coupled terms of bending and torsion are added to the elastic strain energy. Also, the potential energy due to initial stress resultants is consistently derived corresponding to the semitangential rotation and moment. The cubic Hermitian polynomials are utilized as shape functions for development of the curved thin-walled beam element having eight degrees of freedom. In order to illustrate the accuracy and practical usefulness of this study, . numerical solutions for free vibration of arches are presented and compared with resells of other researchers and solutions analyzed by the ABAQUS's shell element.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.1491-1494
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• 2008

Typically internal mobile LCD display modules are connected to the mobile product baseband PCB with flexible printed circuit board equipped with board-to-board connector. This solution has a drawback of limiting the product concept work to certain solutions that are based on connector size, location, flexible PCB length, bending, etc. in the display module. Also flexible printed circuit board based solutions are not completely optimized from reliability point of view, causing flex circuit board breakings. For the external displays in the PC or Home entertainment market, the cable solution is too expensive and resource demanding. The wireless solution has obvious advantages over reliability, low cost and flexibility. This paper describes a wireless audio-visual interface solution.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.830-833
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• 2006

In this work, we provided a novel test method to verify the sealing materials for flexible LCD cell. The ultraviolet type curing sealing material with low process temperature was suitable for LCD cell assembly. We also proposed the sealing materials which passed 13200 times bending test within 20 mm curvature.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.183-186
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• 2003

Long shafts for power transmission should transmit torsional load with vibrational stability. Hybrid shafts made of unidirectional fiber-reinforced composite and metal have high fundamental bending natural frequency as well as high torque transmission capability. However, thermal residual stresses due to the coefficient difference of thermal expansion of the composite and metal are developed so that the high residual stresses decrease fatigue resistance of the hybrid shafts, especially at low operating temperatures. In this work, axial compressive preload was given to the shaft in order to change the residual stresses. Static and fatigue torsional tests were performed and correlated with stress analyses with respect to the preload and service temperature.

• Journal of Mechanical Science and Technology
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• v.17 no.1
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• pp.64-76
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• 2003

In this work, a new penalty formulation is proposed for the analysis of Mindlin-Reissner plates by using the element-free Galerkin method. A penalized weak form for the Mindlin-Reissner Plates is constructed through the exterior penalty method to enforce the essential boundary conditions of rotations as well as transverse displacements. In the numerical examples, some typical problems of Mindlin-Reissner plates are analyzed, and parametric studies on the order of integration and the size of influence domain are also carried out. The effect of the types of background cells on the accuracy of numerical solutions is observed and a proper type of background cell for obtaining optimal accuracy is suggested. Further, optimal order of integration and basis order of Moving Least Squares approximation are suggested to efficiently handle the irregularly distributed nodes through the triangular type of background cells. From the numerical tests, it is identified that unlike the finite element method, the proposed element-free Galerkin method with penalty technique gives highly accurate solution without shear locking in dealing with Mindlin-Reissner plates.