• Title/Summary/Keyword: 판두께 효과

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Three-Dimensional Vibration Analysis of Rectangular Laminated Composite Plates with Combination of Clamped and Free Boundary Conditions (고정과 자유경계조건의 조합을 고려한 직사각형 복합적층판의 3차원 진동해석)

  • Kim, Joo woo
    • Journal of Korean Society of Steel Construction
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    • v.18 no.2
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    • pp.161-171
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    • 2006
  • paper presents the results of a three-dimensional study of the natural vibration of laminated composite rectangular plates with various combinations of clamped and free boundaries. The Ritz method was used to obtain the stationary values of the associated Lagrangian, with displacements approximated using mathematicaly complete, characteristic orthogonal polynomials. The correctness of the three-dimensional model was established through a convergence study of the non-dimensional frequencies, followed by a comparison of the analytical findings in the existing literature. The wide scope of additional three-dimensional frequency results explains the influence of a number of geometrical and material parameters for angle-ply and cross-ply laminated plates, namely aspect ratio (${\mathcal{a/b}}$), thickness ratio (${\mathcal{a/h}}$), orthotropy of material, number of plies (${\mathcal{N}}$), fiber orientation angle (${\theta}$), and stacking sequence.

Analytical and Experimental Study on the Damping of Vibrating Layered Plates Including the Effects of Shear and Thickness Deformation of the Adhesive Layer (접착제층의 전단과 법선변형 효과를 고려한 적층판의 진동감쇠특성 연구)

  • 김재호;박태학
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.16 no.7
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    • pp.1244-1254
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    • 1992
  • This paper investigates the vibrational damping characteristics of laminated plates composed of elastic, viscoelastic and elastic layers by theoretical and experimental methods. Laminated plates are in cylindrical bending and visco-elastic adhesive layer is assumed as the visco-elastic spring which takes damping effect through both shear and normal deformations. Governing equations oof laminated plates are derived in the form of simultaneous first order differential equations, which account for the longitudinal displacements, rotary inertia and shear deformations of elastic base plate and elastic constraining plate. The numerical calculations of the equations are illustrated by the applications to the cantilever beam in transverse vibration. The results of the solutions agree well with the experimental measurements in general. The damping effects due to the shear and thickness deformations in the adhesives are analyzed and it is shown that for thicker adhesives, the damping effect due to thickness deformation becomes significant and for thinner adhesives, due to shear deformation.

Thermal Stress Relief through Introduction of a Microtrench Structure for a High-power-laser-diode Bar (높은 광출력을 갖는 Laser Diode Bar의 열응력 개선: 마이크로-홈 도입을 통한 응력 분포 변화 분석)

  • Jeong, Ji-Hun;Lee, Dong-Jin;O, Beom-Hoan
    • Korean Journal of Optics and Photonics
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    • v.32 no.5
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    • pp.230-234
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    • 2021
  • Relief of thermal stress has received great attention, to improve the beam quality and stability of high-power laser diodes. In this paper, we investigate a microtrench structure engraved around a laser-diode chip-on-submount (CoS) to relieve the thermal stress on a laser-diode bar (LD-bar), using the SolidWorks® software. First, we systematically analyze the thermal stress on the LD-bar CoS with a metal heat-sink holder, and then derive an optimal design for thermal stress relief according to the change in microtrench depth. The thermal stress of the front part of the LD-bar CoS, which is the main cause of the "smile effect", is reduced to about 1/5 of that without the microtrench structure, while maintaining the thermal resistance.

A Parametric Study on the Strength of Single-Lap Bonded Joints of Carbon Composite and Aluminum (탄소 복합재-알루미늄 단일겹침 접착 체결부의 강도에 관한 인자연구)

  • Kim, Tae-Hwan;Seong, Myeong-Su;Choi, Jin-Ho;Kweon, Jin-Hwe
    • Composites Research
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    • v.20 no.5
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    • pp.34-42
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    • 2007
  • Strength and failure of adhesively bonded carbon composite-to-aluminum single-lap joints were studied by experiment. The main objective of this study is to investigate the effect of various parameters such as curing pressure for bonding, overlap lengths, and adherend thickness on the failure loads and modes of the bonded Joints with dissimilar materials. Experimental results show that the bonding pressure for composite-to-aluminum dissimilar materials should be 4 atm at the lowest. Failure load of the joints increases as the overlap length increases, but the strength (failure load divided by bonded area) decreases rapidly after the overlap width-to-length ratio is greater than 1. When the adherend thickness increase to double, bonding strength increase $12{\sim}55%$. Major failure mode of the joints is the delamination in the composite laminate and the location of delamination goes deeper into the laminates as the bonding pressure and overlap length increase.

Jangdo(Small Ornamental Knives) manufacturing process and restoration research using Odong Inlay application (오동상감(烏銅象嵌)기법을 활용한 장도(粧刀)의 제작기술 및 복원연구)

  • Yun, Yong Hyun;Cho, Nam Chul;Jeong, Yeong Sang;Jang, Chu Nam
    • Korean Journal of Heritage: History & Science
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    • v.49 no.2
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    • pp.172-189
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    • 2016
  • In this research, literature research on the Odong material, mixture ratio, casting method and casting facility was conducted on contemporary documents, such as Cheongong Geamul. Also, a long sword was produced using the Odong inlay technique. The sword reproduction steps were as follows; Odong alloying, silver soldering alloying, Odong plate and Silver plate production, hilt and sheath production, metal frame and decorative elements, such as a Dugup (metal frame), production, Odong inlay assembly and final assembly. For the Odong alloy production, the mixture ratio of the true Odong, which has copper and gold ratio of 20:1, was used. This is traditional ratio for high quality product according to $17^{th}$ century metallurgy instruction manual. The silver soldering alloy was produced with silver and brass(Cu 7 : Zn 3) ratio of 5:1 for inlay purpose and 5:2 ratio for simple welding purpose. The true Odong alloy laminated with silver plate was used to produce hilt and sheath. The alloy went through annealing and forging steps to make it into 0.6 mm thick plate and its backing layer, which is a silver plate, had the matching thickness. After the two plates were adhered, the laminated plate went through annealing, forging, engraving, silver inlaying, shaping, silver welding, finishing and polishing steps. During the Odong colouring process, its red surface turns black by induced corrosion and different hues can be achieved depending on its quality. To accomplish the silver inlay Odong techniques, a Hanji saturated with thirty day old urine is wrapped around a hilt and sheath material, then it is left at warm room temperature for two to three hours. The Odong's surface will turn black when silver inlay remains unchanged. Various scientific analysis were conducted to study composition of recreated Odong panel, silver soldering, silver plate and the colouring agent on Odong's surface. The recreated Odong had average out at Cu 95.57 wt% Au 4.16wt% and Cu 98.04 wt% Au 1.95wt%, when documented ratio in the old record is Cu 95wt% and Au 5wt%. The recreated Odong was prone to surface breakage during manufacturing process unlike material made with composition ratio written in the old record. On the silver plate of the silver and Odong laminate, 100wt% Ag was detected and between the two layers Cu, Ag and Au were detected. This proves that the adhesion between the two layers was successfully achieved. The silver soldering had varied composition of Ag depending on the location. This shows uneven composition of the silver welding. A large quantities of S, that was not initially present, was detected on the surface of the black Odong. This indicates that presence of S has influence on Odong colour. Additional study on the chromaticity, additional chemical compounds and its restoration are needed for the further understanding of the origin of Odong colour. The result of Odong alloy testing and recreation, Odong silver inlay long sword production, scientific analysis of the Odong black colouring agent will form an important foundation of knowledge for conservation of Odong artifact.

Bond Strength of Near Surface-Mounted FRP Plate in RC Member (콘크리트 내에 표면매입 보강된 FRP 판의 부착강도)

  • Seo, Soo-Yeon
    • Journal of the Korea Concrete Institute
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    • v.24 no.4
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    • pp.415-422
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    • 2012
  • This paper analyzed seventy eight previous test results to evaluate bond strength of Near Surface-Mounted (NSM) FRP and prediction formulas previously proposed by researchers. The results showed that the most reliable bond strength prediction was the one proposed by Seracino, who considered the shape coefficient (ratio of width-thickness) and stiffness of FRP. However, the equation tended to underestimate the bond strength, especially serious when FRP bond length was relatively short, because the equation did not consider the effect of bond length. Based on the analysis of previous test results, the relation between bond length and bond strength and the group effect due to close proximity of FRPs were determined. Based on the findings, the Seracino's formula was modified and it's applicability was evaluated. The result showed that the suggested formula can be used effectively to predict the bond strength of NSM FRP.

Biaxial Buckling Analysis of Magneto-Electro-Elastic(MEE) Nano Plates using the Nonlocal Elastic Theory (비국소 탄성이론을 이용한 자기-전기-탄성 나노 판의 2방향 좌굴 해석)

  • Han, Sung-Cheon;Park, Weon-Tae
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.30 no.5
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    • pp.405-413
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    • 2017
  • In this paper, we study the biaxial buckling analysis of nonlocal MEE(magneto-electro-elastic) nano plates based on the first-order shear deformation theory. The in-plane electric and magnetic fields can be ignored for MEE(magneto-electro-elastic) nano plates. According to magneto-electric boundary condition and Maxwell equation, the variation of magnetic and electric potentials along the thickness direction of the MME plate is determined. In order to reformulate the elastic theory of MEE(magneto-electro-elastic) nano-plate, the nonlocal differential constitutive relations of Eringen is used. Using the variational principle, the governing equations of the nonlocal theory are discussed. The relations between nonlocal and local theories are investigated by computational results. Also, the effects of nonlocal parameters, in-plane load directions, and aspect ratio on structural responses are studied. Computational results show the effects of the electric and magnetic potentials. These computational results can be useful in the design and analysis of advanced structures constructed from MEE(magneto-electro-elastic) materials and may be the benchmark test for the future study.

Effects of Transverse Shear Deformation and Rotary Inertia on Vibration of Rotating Polar Orthotropic Disks (극직교 이방성 회전원판의 진동에 대한 횡전단변형 및 회전관성 효과)

  • Kim, Dong-Hyun;Koo, Kyo-Nam
    • Composites Research
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    • v.20 no.3
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    • pp.43-49
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    • 2007
  • Dynamic instability of rotating disks is the most significant factor to limit its rotating speed. Application of composite materials to rotating disks may enhance the dynamic stability leading to a possible design of rotating disks with lightweight and high speed. Whereas much work has been done on the effect of transverse shear and rotary inertia, called Timoshenko effect, on the dynamic behavior of plates, there is little work on the correlation between the effect and the rotation of disk, especially nothing in case of composite disks. The dynamic equations of a rotating composite disk are formulated with the Timoshenko effect and the vibrational analysis is performed by using a commercial package MSC/NASTRAN. According to the results, the Timoshenko effect goes seesaw in some modes, unlike the well-known fact that the effect decreases as the rotating speed increases. And it can be concluded, based only on the present results, that decrement of the Timoshenko effect by disk rotation grows larger as the thickness ratio decreases, the diameter ratio increases, the modulus ratio increases, and the mode number increases.

Bending Effect of Laminated Plates with a Circular Hole Repaired by Single-Sided Patch Based on p-Convergent Full Layerwise Model (p-수렴 완전층별모델에 의한 일면패치로 보강된 원공 적층판의 휨효과)

  • Woo, Kwang-Sung;Yang, Seung-Ho;Ahn, Jae-Seok;Shin, Young-Sik
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.5
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    • pp.463-474
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    • 2009
  • Double symmetric patch repair of existing structures always causes membrane action only, however, in many cases this technique is not practical. On the other hand, the bending stiffness of the patch and the skin increases as tensile loading is increased and affects the bending deformation significantly in the case of single-sided patch repair. In this study, the p-convergent full layerwise model has been proposed to determine the stress concentration factor in the vicinity of a circular hole as well as across the thickness of plates with single-sided patch repair. In assumed displacement field, the strain-displacement relations and 3-D constitutive equations of a layer are obtained by the combination of 2-D and 3-D hierarchical shape functions. The transfinite mapping technique has been used to represent a circular boundary and Gauss-Lobatto numerical integration is implemented in order to directly obtain stresses occurred at the nodal points of each layer without other extrapolation techniques. The accuracy and simplicity of the present model are verified with comparison of the previous results in literatures using experiment and conventional 3-D finite element. Also, the bending effect has been investigated with various patch types like square, circular and annular shape.

Bending and Vibration Analysis of Elastic and Viscoelastic Laminated Composite Structures using an Improved Higher-order Theory (개선된 고차이론을 이용한 복합재료 적층구조물의 탄성 및 점탄성적 휨, 진동해석)

  • Han, Sung Cheon;Yoo, Yong Min;Park, Dae Yong;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.14 no.1
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    • pp.1-12
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    • 2002
  • To obtain more accurate responses of laminated composite structures, the effect of transverse shear deformation, transverse normal strain/stress and a nonlinear variation of in-plane displacements with respect to the thickness coordinate need to be considered in the analysis. The improved higher-order theory is used to determine the deflections and natural frequencies of laminated composite structures. A quasi-elastic method is used for the solution of viscoelastic analysis of the laminated composite plates and sandwiches. Solutions of simply-supported laminated composite plates and sandwiches are obtained and the results are compared with those by the 3D elasticity theory and other theories. The improved theory proposed in this paper is shown to predict the deflections and natural frequencies more accurately than all other theories.