• 한국소음진동공학회논문집
• /
• 제23권1호
• /
• pp.84-91
• /
• 2013

Ultrasonic flip-chip bonding needs a precise bonding tool which delivers ultrasonic energy into chip bumps effectively to use the selected resonance mode and frequency of the horn structure. The bonding tool is excited at the resonance frequency and the input and output ports should locate at the anti-nodal points of the resonance mode. In this study, we propose new design method with topology optimization for ultrasonic bonding tools. The SIMP(solid isotropic material with penalization) method is used to formulate topology optimization and OC(optimal criteria) algorithm is adopted for the update scheme. MAC(modal assurance criterion) tracking is used for the target frequency and mode. We fabricate two prototypes of ultrasonic tools which are based on 3D optimization models after reviewing 2D and 3D topology optimization results. The prototypes are satisfied with the ultrasonic frequency and vibration amplitude as the ultrasonic bonding tools.

• 대한기계학회논문집A
• /
• 제36권4호
• /
• pp.451-455
• /
• 2012

수학적 방법에 기초한 점근해석기법은 이방성 보 구조물의 설계 및 해석에 있어 강력한 도구이다. 이러한 장점에도 불구하고, 점근해석 기법은 전단 변형에 상대적으로 취약한 복합재료 보의 고차해를 구함에 있어 점근적으로 정확한 경계조건을 필요로 한다. 생브낭의 원리를 적용하여 응력상태를 개선하는 방법은 등방성 보 및 판 구조물에 대하여 개발되었고, 외팔보 등의 예제를 통해 검증되었다. 이 방법은 점근적으로 정확한 경계조건을 요구하지 않으며, 반복계산도 필요로 하지 않는다는 장점이 있다. 본 논문에서는 이 방법을 일반 이방성 보 구조물에 대하여 확장 적용하여 생브낭의 원리를 적용하는 방법을 일반화 하고자 한다.

• International Journal of Aeronautical and Space Sciences
• /
• 제2권2호
• /
• pp.65-72
• /
• 2001

This paper demonstrates an explicit-implicit, finite element analysis for linear as well as nonlinear hygrothermal stress problems. Additional features, such as moisture diffusion equation, crack element and virtual crack extension(VCE) method for evaluating J-integral are implemented in this program. The Linear Elastic Fracture Mechanics(LEFM) Theory is employed to estimate the crack driving force under the transient condition for an existing crack. Pores in materials are assumed to be saturated with moisture in the liquid form at the room temperature, which may vaporize as the temperature increases. The vaporization effects on the crack driving force are also studied. The ideal gas equation is employed to estimate the thermodynamic pressure due to vaporization at each time step after solving basic nodal values. A set of field equations governing the time dependent response of porous media are derived from balance laws based on the mixture theory. Darcy's law is assumed for the fluid flow through the porous media. Perzyna's viscoplastic model incorporating the Von-Mises yield criterion are implemented. The Green-Naghdi stress rate is used for the invariant of stress tensor under superposed rigid body motion. Isotropic elements are used for the spatial discretization and an iterative scheme based on the full Newton-Raphson method is used for solving the nonlinear governing equations.

• 대한조선학회논문집
• /
• 제50권5호
• /
• pp.349-354
• /
• 2013

The blades of flexible propellers are formed by overlaying and adhering many layers of thin glass-fiber fabric sheets, are compressed and dried in the rigid mold. The current manufacturing process can not avoid the rather irregular deformation of the blades composed of non-isotropic non-uniform fabric structures, and inevitably introduces the different shape-forming errors between blades. In this paper, several flexible model propellers are precisely measured with three-dimensional optical instrument and compared with the original design geometry. The model propellers with the as-measured geometry are evaluated with the lifting-surface-theory-based propeller analysis code. The open-water performance are presented and discussed. The importance of the manufacturing accuracy is addressed to be able to apply the flexible propellers for propulsion of marine vehicles.

• Composites Research
• /
• 제12권2호
• /
• pp.46-52
• /
• 1999

본 연구는 면내 전단과 휨을 동시에 받는 직교이방성 구조재의 복부판의 탄성좌굴거동에 대한 해석적 연구결과이다. 펄트루젼 방법으로 생산된 섬유보강 플래스틱을 직교이방성으로 간주하였다. 복부판의 좌굴해석에서 직교이방성 재료의 역학적 성질을 고려할 수 있도록 기존의 등방성 판의 좌굴해석을 위해 개발된 이론적 해를 확장하였다. 이론식의 해를 구하는 방법으로 Rayleigh-Ritz법을 사용하였으며, 면내 전단과 휨을 동시에 받는 복부판의 탄성좌굴강도를 구할 수 있는 그래프를 제시하였다. 전단과 휨의 상호작용과 관련된 설계기준에 대해서도 도한 검토하였다.

• Smart Structures and Systems
• /
• 제12권5호
• /
• pp.523-545
• /
• 2013

Piezoelectric and dielectric behaviors of a piezoceramic patch adhesively centered on a carbon composite plate are identified using a robust multi-objective optimization procedure. For this purpose, the patch piezoelectric stress coupling and blocked dielectric constants are automatically evaluated for a wide frequency range and for the different identifiable behaviors. Latters' symmetry conditions are coded in the design plans serving for response surface methodology-based sensitivity analysis and meta-modeling. The identified constants result from the measured and computed open-circuit frequencies deviations minimization by a genetic algorithm that uses meta-model estimated frequencies. Present investigations show that the bonded piezoceramic patch has effective three-dimensional (3D) orthotropic piezoelectric and dielectric behaviors. Besides, the sensitivity analysis indicates that four constants, from eight, dominate the 3D orthotropic behavior, and that the analyses can be reduced to the electromechanically coupled modes only; therefore, in this case, and if only the dominated parameters are optimized while the others keep their nominal values, the resulting piezoelectric and dielectric behaviors are found to be transverse-isotropic. These results can help designing piezoceramics smart composites for various applications like noise, vibration, shape, and health control.

• Steel and Composite Structures
• /
• 제12권3호
• /
• pp.249-260
• /
• 2012

In this study, stress and deflection behaviours of T-type welding joint applied to HE200M steel beam and column were investigated in finite element method (FEM) under different distributed loads. In the 3D-FEM modelling, glue option was used to contact between steel materials and weld nuggets. Geometrical model was designed as 3-dimensional solid in ANSYS software program. After that, homogeneous, linear and isotropic properties were used to design to materials of model. Solid-92 having 3-dimensional, 4 faced and 10-noded was selected as element type. In consequence of mesh operation, elements of 13285 and nodes of 28086 were occurred. Load distribution was applied to top surface of steel beam to determine behaviours of stress and deflection. As a result of FEM analysis applied with the loads of 55,000 N, 110,000 N and 220,000 N, maximum values were obtained as 116 N/$mm^2$, 232 N/$mm^2$ and 465 N/$mm^2$ for stress and obtainedas 1,083 mm, 2,166 mm and 4.332 mm for deflection, respectively. When modelling results and classical calculation values were compared, it was obtained difference of 10 % for stress values and 2.5% for deflection values.

• Nuclear Engineering and Technology
• /
• 제25권1호
• /
• pp.80-90
• /
• 1993

원자력발전소에는 방사선 차폐체를 통한 수 많은 관통부들이 존재하며. 이를 통한 방사선 스트리밍의 해석은 발전소 작업자들의 방호를 위한 차폐 설계에 있어 중요한 고려사항 중 하나이다. 본 연구에서는 관통부 중 주종을 이루는 콘크리트 벽체 내 원통형 직관통부로 단방향. 단일 에너지의 감마선 면선원에 의한 방사선 스트리밍 해석을 위하여 몬테칼로방법에 따른 전산 프로그램을 개발하였으며, 이를 사용하여 여러 경우의 감마선원 에너지와 입사각. 관통부의 반경과 길이에 대하여 관통부 출구에서의 평균 선량을 계산하여 그 결과를 라이브러리화 하였다 또한. 이를 이용하여 등방향 점선원에 대하여 적절히 근사할 수 있음을 보임으로서 임의의 감마선원 분포에 대하여 짧은 전산시 간으로 정확한 결과를 구할 수 있는 방법을 제공하였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2004년도 추계학술대회논문집
• /
• pp.928-933
• /
• 2004

The vibration characteristic is a primary design factor. The cylindrical shells are used as a primary components of complex structure. also, The cylindrical shells have oblique angle. In this study, The vibrational characteristics of steel and plain wave GFRP cylindrical shell with an oblique end are given by experimental and finite element method. To be find characteristic of the oblique end, the mass of the cylindrical shell is maintained. Natural frequency and mode shapes of isotropic and plain weave composite shells are obtained by modal test. The results are compared with those of the finite element method. The simply supported boundary conditions with bolts along the circumferential direction of the GFRP shell are well achieved. Also, The clamped boundary conditions is applied to the steel specimen. Those are shown to agree well with the analytical results and finite element analysis results.

• Structural Engineering and Mechanics
• /
• 제69권6호
• /
• pp.667-676
• /
• 2019

Minimizing the stress concentration around hypotrochoid hole in finite metallic plates under in-plane loading is an important consideration in engineering design. In the analysis of finite metallic plate, the effective factors on stress distribution around holes include curvature radius of the corner of the hole, hole orientation, plate's aspect ratio, and hole size. This paper aims to investigate the impact of these factors on stress analysis of finite metallic plate with central hypotrochoid hole. To obtain the lowest value of stress around a hypotrochoid hole, a swarm intelligence optimization method named ant lion optimizer is used. In this study, with the hypothesis of plane stress circumstances, analytical solution of Muskhelishvili's complex variable method and conformal mapping is employed. The plate is taken into account to be finite, isotropic and linearly elastic. By applying suitable boundary conditions and least square boundary collocation technique, undefined coefficients of stress function are found. The results revealed that by choosing the above-mentioned factor correctly, the lowest value of stress would be obtained around the hole allowing to an increment in load-bearing capacity of the structure.