• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
• /
• pp.12-18
• /
• 2002

For the analysis of Kirchhoff plate bending problems, a new meshless method is implemented. For the satisfaction of the C¹ continuity condition in which the first derivative is treated as another primary variable, Hermite interpolation is enforced on standard reproducing kernel particle method. In order to impose essential boundary conditions on solving C¹ continuity problems, shape function modifications are adopted. Through numerical tests, the characteristics and accuracy of the HRKPM are investigated and compared with the finite element analysis. By this implementation, it is shown that high accuracy is achieved by using HRKPM fur solving Kirchhoff plate bending problems.

• 풍력에너지저널
• /
• 제14권2호
• /
• pp.26-33
• /
• 2023

In this study, the global response characteristics of floater and mooring for floating offshore wind turbine with a detachable mooring system are performed. Global motion and structural response result extracted from the coupled motion analysis of 10MW DTU floating offshore wind turbine with detachable mooring system modeled by high-order boundary element model and finite element mesh, were used to study the characteristics of tension on mooring lines subjected to three different types of ocean loads. Breaking limit of mooring line characterized by wind, current and wave load has a major effect on the distribution of mooring tension found in time domain analysis. Based on the numerical results of coupled motion analysis, governing equation for calculating the motion response of a floater under ocean loads, and excitation force and surge motion and tension respectively are presented using excursion curve. It is found that the response of floater is reliable and accurate for calculating the tension distributions along the mooring lines under complex loadings. This means that the minimun breaking limit of mooring system satisfied a design criteria at ultimate ocean environmental loading condtions.

• Structural Engineering and Mechanics
• /
• 제68권6호
• /
• pp.713-720
• /
• 2018

In this paper a new numerical method to determine the elastic curve of the simply supported beams of variable cross-section is demonstrated. In general case it needs to solve linear or small nonlinear second order differential equations with prescribed boundary conditions. For numerical solution the initial values of the slope and the deflection of the end cross-section of the beam is necessary. For obtaining the initial values a lively procedure is developed: it is a special application of the shooting method because boundary value problems can be transformed into initial value problems. As a result of these transformations the initial values of the differential equations are obtained with high accuracy. Procedure is applied for calculating of elastic curve of a simply supported beam of variable cross-section. Results of these numerical procedures, analytical solution of the linearized version and finite element method are compared. It is proved that the suggested procedure yields technically accurate results.

• 대한기계학회논문집A
• /
• 제41권6호
• /
• pp.455-467
• /
• 2017

본 논문에서는 원통형 다층 이종 금속 용접부를 대상으로 유한요소 해석을 수행하여, 열원 입력 방법과 용접 비드 생성 방법이 용접 잔류 응력 분포에 미치는 영향을 고려하였다. 열원 입력 방법은 열속 입력 방법과 온도 경계조건 입력 방법으로 나누어 비교하였고, 용접 비드 생성 방법은 요소망 생성 방법과 평온 요소망 방법으로 나누어 비교하였다. 두 열원 입력 방법에 따른 열 해석 결과는 차이가 있었으나, 응력 해석 결과는 유사하였다. 이것은 고온(약 $1000^{\circ}C$ 이상)에 노출되었던 영역이 비슷하고, 고온에서 재료의 강도가 매우 낮아 용접 비드의 온도가 용접잔류응력에 미치는 영향이 미미하기 때문이다. 두 용접 비드 생성 방법의 용접 잔류응력 분포는 유사하였지만 요소망 생성 방법 적용 시 용접 비드 경계에서 겹침과 들뜸이 발생하였다. 대변형이 발생하는 모델의 용접부 형상을 정확하게 모사하기 위해서는 평온요소망이 더 적합하다고 판단된다.

• 한국자동차공학회논문집
• /
• 제11권3호
• /
• pp.28-38
• /
• 2003

Finite element analysis of cylinder heat/block compound under assembly, thermal and firing condition were performed. FE model including two cylinders with gasket, head bolts, liners and valve seats was used. FE modeling method and boundary conditions were introduced. Stress distribution and deformation of cylinder head and block under each loading condition were presented. Gasket pressure distribution and bore distortion level were predicted. Measured data of bore distortion was compared with the analysis results. The analysis result showed similar trends with the experimental data. High cycle fatigue analysis on the basis of this result has been performed in order to find the critical areas of the engine assembly.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2007년도 정기 학술대회 논문집
• /
• pp.577-582
• /
• 2007

A variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions in analysis domain arc generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Thus. the solution space can be represented in terms of the same functions to represent the geometry. The coefficients of basis functions or the control variables play the role of degrees-of-freedom. Furthermore, due to h-. p-, and k-refinement schemes, the high order geometric features can be described exactly and easily without tedious re-meshing process. The isogeometric sensitivity analysis method enables us to analyze arbitrarily shaped structures without re-meshing. Also, it provides a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling. To obtain precise shape sensitivity, the normal and curvature of boundary should be taken into account in the shape sensitivity expressions. However, in conventional finite element methods, the normal information is inaccurate and the curvature is generally missing due to the use of linear interpolation functions. A continuum-based adjoint sensitivity analysis method using the isogeometric approach is derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of boundary. In isogeometric analysis, however, the geometric properties arc already embedded in the B-spline shape functions and control points. The perturbation of control points in isogeometric analysis automatically results in shape changes. Using the conventional finite clement method, the inter-element continuity of the design space is not guaranteed so that the normal vector and curvature arc not accurate enough. On tile other hand, in isogeometric analysis, these values arc continuous over the whole design space so that accurate shape sensitivity can be obtained. Through numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.

• Structural Engineering and Mechanics
• /
• 제70권2호
• /
• pp.199-207
• /
• 2019

In this paper, a semi-analytical method will be discussed for free vibration analysis of rotating beams with variable cross sectional area. For this purpose, the rotating beam is discretized through applying the transfer matrix method and assumed the axial force is constant for each element. Then, the transfer matrix is derived based on Euler-Bernoulli's beam differential equation and applying boundary conditions. In the following, the frequencies of the rotating beam with constant and variable cross sections are determined using the transfer matrix method in several case studies. In order to eliminate numerical difficulties in the transfer matrix method, the Riccati transfer matrix is employed for high rotation speed and high modes. The results are compared with the results of the finite elements method and Rayleigh-Ritz method which show good agreement in spite of low computational cost.

• Steel and Composite Structures
• /
• 제38권3호
• /
• pp.281-291
• /
• 2021

An equivalent single-layer theory (EST) is put forward for analyzing free vibrations of steel-concrete composite beams (SCCB) based on a higher-order beam theory. In the EST, the effect of partial interaction between sub-beams and the transverse shear deformation are taken into account. After using the interlaminar shear force continuity condition and the shear stress free conditions at the top and bottom surface, the displacement function of the EST does not contain the first derivatives of transverse displacement. Therefore, the C0 interpolation functions are just demanded during its finite element implementation. Finally, the EST is validated by comparing the results of two simply-supported steel-concrete composite beams which are tested in laboratory and calculated by ANSYS software. Then, the influencing factors for free vibrations of SCCB are analyzed, such as, different boundary conditions, depth to span ratio, high-order shear terms, and interfacial shear connector stiffness.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제49권5호
• /
• pp.291-296
• /
• 2000

Recently large size color TV and computer monitor are very popular and a lot techniques are being developed to get a high quality picture on the screen through reducing the convergence error among the red, green and blue beams and achieving a high focusing. One of the techniques is considering the mutual effects of the components of the Brown tube. The magnetic deflection yoke, especially, stands immediately next to the electron gun and generates the leakage magnetic fields at the electron gun which affects the trajectories of the electron beams inside the gun. Hence a shield cup made of thin conducting plate is located at the end of electron gun in order to shield the leakage flux from the deflection yoke. Since the red, green and blue beams are placed unsymmetrically the shielding effects of the shield cup on the beams are not same and eddy current controller, made of thin conducting plate, is auxiliary placed inside the shield cup. In this paper a transient magnetic field analysis algorithm is developed using boundary element method, and applied to the analysis of the shielding effects of the eddy current controller of shield cup in an electron gun.

• 한국철도학회논문집
• /
• 제16권1호
• /
• pp.20-25
• /
• 2013

고속철도 차량의 프레임은 굽힘 강성이 높고 가벼운 알루미늄 압출재를 이용하고 있으나, 그 차음성능은 동일 면밀도의 평판에 비하여 취약하다. 본 연구에서는 유한요소해석을 통하여 알루미늄 압출재의 음향투과 손실 값을 예측하는 방법을 제시하였다. 압출재를 유한요소로 모델링하고 무반사 방사조건, 시편의 경계 조건, 재질의 감쇠손실계수 등을 사용하여 투과손실을 예측하였으며, 해석결과의 신뢰도를 검증하기 위하여 압출재 시편을 대상으로 ASTM E2249-02에 근거한 투과손실을 측정하였다. 제시된 해석방법은 철도차량용 알루미늄 압출재의 차음특성을 설계단계에서 파악하고 대책을 수립하는데 유용하게 활용될 것이다.