• Proceedings of the Korean Society of Disaster Information Conference
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• 2016.11a
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• pp.188-189
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• 2016

본 논문은 초기하중을 하중을 받는 역대칭 angle-ply 와 cross-ply 적층판의 좌굴 및 진동특성을 무재하시의 고유진동수를 이용하여 산정하는 간편법을 제시하였다. 마주보는 두변이 단순 지지된 역대칭 적층판의 운동방정식은 전단변형과 회전강성효과를 고려한 YSN 이론으로 유도하였으며 이를 선점법을 이용하여 해석하였다. 초기응력을 받는 적층판의 무차원화 고유진동수, 임계좌굴계수 및 동적 주 불안정영역 문제들을 무재하시의 무차원화 고유진동수로서 각각의 특성을 정립시켰다. 본 연구에서 제안한 진동특성에 관한 간편산정식의 정당성과 사용성을 입증하기 위하여 수치예들로서 검토하였다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.303-309
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• 2011

Laminated rubber bearing is the most commonly used device for seismic base isolation of bridge structures. It is important to know performance and behavior characteristics of the laminated rubber bearings. The main evaluation factors of the rubber bearing are classified as compressive, shear and tensile behavior characteristics. The reference data of compressive and shear characteristics are rich, but the reference data of tensile characteristics is scarce. In this study, tensile test results of the rubber bearing with variation of shape factor and shear deformation are investigated for mechanical property. When tensile deformation in normal condition is increasing, tensile cycle behavior curve becomes non-linear and tensile breaking point is 300%. On the other hand, tensile breaking point is shear deformation condition is about 40%. Furthermore, when shape factor is lower, tensile breaking point is decrease. This results mean that tensile breaking point is decreased in triaxial tensile deformation because of cracks caused by internal void of the rubber bearings. This experimental data can be used as the reference data of tensile characteristics for designing seismic isolation of structures.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.11
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• pp.1239-1243
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• 2014

This paper presents the application of carbon-fiber-reinforced polymer (CFRP) for the damage absorption and optimal design of portable smart devices to close in life. CFRP specimens are subjected to a tensile test to estimate their mechanical properties in terms of the stacking angles. Further, the screw reverse torque and screw torque at each stacking angle are determined using a torque tester after tapping holes on the CFRP specimens. Two experiments are performed for comparing their results in order to determine optimal conditions. In the tensile test, a woven specimen is found to have the highest strength and stiffness. In the case of the woven specimen, no difference is observed even when it is applied to prevent loosening of the coating. And average result value was excellent.

• Composites Research
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• v.12 no.6
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• pp.1-7
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• 1999

The change of the coefficients of thermal expansion(CTE) of Carbon/Epoxy was investigated for the temperature variation and a prediction model for the change of CTE was proposed. Elastic properties and CTEs in the principal material directions were measured in the range of room temperature to cure temperature and characterized as functions of temperature. By applying the characterized properties to the classical lamination theory, a computational method to predict the change of CTEs of a general laminate for temperature variation was proposed. the coefficients of thermal expansion of laminates with various stacking sequences were measured and compared with those predicted. Good agreements between the predicted results and the experimental data show that the c hanges of CTEs of a general laminate for temperature variation can be predicted well by using the proposed method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07b
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• pp.684-687
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• 2004

일반적으로 적층형 압전 액츄에이터의 변위는 액츄에이터의 내부 적층수와 압전정수($d_{33}$)에 비례적으로 증가한다. 그러나 압전현상을 이용한 액츄에이터는 전기적, 기계적 부하에 의한 dipole 거동을 보이기 때문에 domain wall에 의한 압전정수의 비선형 거동을 보인다. 본 논문에서는 PMN-PZ-PT 세라믹스를 이용하여 $2{\times}3{\times}10$ (mm)의 적층형 세라믹 액츄에이터를 제조 후 1kV/mm의 일정한 전계를 인가하고 $0\sim990N$의 기계적 부하 인가하에서 적층형 세라믹 액츄에이터의 비선형 특성을 조사하였다. 압전 액츄에이터의 비선형 거동은 기계적 응력에 의한 유전 및 전왜 특성에 영향주고, 액츄에이터의 변위 특성은 유전 및 전왜 특성의 영향에 크게 의존한다.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.691-700
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• 2000

A powerful analytical procedure and strain energy analysis to investigate the free vibration of antisymmetric angle-ply laminated plates, having one pair of opposite edges simply supported, are develped on the basis of the Yang, Norris and Stavsky (YSN) theory. The equation of motion of the plate are solved by the use of collocation method. A range of results are presented for plates to show the effects of modulus ratio and number of layers on natural frequency. In addition, an analysis of the strain energy distributions is used as an aid for the better understanding of the vibration characteristics of the plates.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.409-415
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• 2011

Optimization Analysis of angle-ply laminated shells, having one pair of opposite edges supported, are investigated on the basis of the first-order shear deformation theory. The equations of motion of the shell are solved by the use of ritz method. A range of results are presented for composite shells to show the effects of lamination angle and number of layers on natural frequency. In addition, an analysis of the strain energy distributions is used as an aid for the better understanding of the vibration characteristics of the shells.

• Composites Research
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• v.20 no.1
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• pp.1-7
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• 2007

This study presents a methodology for optimization of static characteristics of golf club shafts. Stacking sequence for the optimal composite shaft performance is searched. A new objective function is defined for the simultaneous optimization of flexural and torsional stiffnesses. Classical lamination theory is used for the static analysis. As the optimization tool, genetic algorithm is applied with the stacking sequence as design. variables. With the optimal stacking sequence, dynamic characteristics of the shaft is also studied.

• Journal of Korean Association for Spatial Structures
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• v.11 no.3
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• pp.77-83
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• 2011

Laminated composite plates have shown their superiority over metals in applications requiring high specific strength, high specific modulus, and so on. Therefore, they have used in various industry. However, they have poor resistance to impact compared to typical metal materials. To resolve this problem by many researchers for a variety of studies have been attempted. This study investigates characteristic of impact behavior of laminated composite plates due to initial stress. Using finite element program which involved the indentation law, we investigate characteristic of impact behavior of laminated composite plates due to initial stress.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.4
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• pp.599-606
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• 1999

복합 적층 판과 보강 재를 설치한 보강된 복합 적층 패널의 좌굴을 고려한 설계에서, 좌굴이 항상 구조물의 최종 파손을 의미하는 것은 아니므로 이들의 좌굴 및 좌굴 후 거동에 대한 정확한 이해와 연구가 필요하다. 본 연구에서는 유한요소 법을 이용하여 적층 메커니즘과 섬유 배향각, 적층 순서 등이 복합 적층 판과 보강된 복합 적층 패널의 좌굴 및 좌굴 후 거동에 미치는 영향을 체계적으로 해석하였고, 각 변수에 따른 좌굴 및 좌굴 후 거동 특성을 분석하였다.