• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1009-1011
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• 2003

This study investigates the characteristics of Permanent Magnet Assisted Synchronous Reluctance Motor (PMASynRM) using coupled FEM and Preisach modelling. The focus of this paper is the characteristics analysis of d, q axis inductance according to magnetizing direction and quantity of interior permanent magnet far PMASynRM. Investigation on nonlinear characteristic of machine is performed by Preisachs theory application. Comparisons are given with characteristics of normal Synchronous reluctance motor(SynRM) and those according to the quantity of residual flux density (0.3T and 0.4T) in PMASynRM, respectively.

• Smart Structures and Systems
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• 제23권4호
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• pp.337-345
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• 2019

This work resumes a research that proposes the use of the technique based on the dissipation energy of the shape memory alloy (SMA) ties. It focuses principally on the assessment of the effectiveness of the use of these smart materials on displacements, accelerations and the stresses of the minaret of the great mosque of Ajloun in Jordan. The 3-D finite element model of the minaret is performed by the ANSYS software. First of all, the proposed model is calibrated and validated according to the experimental results gathered from ambient vibration testing results. Then, a nonlinear transient analysis is considered, when the El-Centro earthquake is used as the input signal. Different simulating cases concerning the location, number and type of SMA devices are proposed in order to see their influence on the seismic response of the minaret. Hence, the results confirm the effectiveness of the proposed SMA device.

• Structural Engineering and Mechanics
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• 제80권5호
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• pp.595-608
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• 2021

To investigate the mechanical behavior of large stud shear connector embedded in hybrid fiber-reinforced concrete (HFRC), a refined 3D nonlinear finite element (FE) model incorporating the constitutive model of HFRC was developed using ANSYS. Firstly, the test results conducted by the authors (He et al. 2017) were used to validate FE model of push out tests. Secondly, a total of 27 specimens were analyzed with various parameters including fiber volume fractions of HFRC, diameter of studs and HFRC strength. Finally, an empirical equation considering the contribution of steel fiber (SF) and polypropylene fiber (PF) was recommended to estimate the ultimate capacity of large stud shear connector embedded in HFRC.

• Steel and Composite Structures
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• 제49권2호
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• pp.197-213
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• 2023

To investigate the static properties of large high strength bolt shear connector in hybrid fiber-reinforced concrete (HFRC) and normal concrete (NC), eight push-out test specimens with single/double nut and HFRC/NC slabs were designed and push-out tests were conducted. A fine 3D nonlinear finite element (FE) model including HFRC constitutive model was established by using ANSYS 18.0, and the test results were used to verify FE models of the push-out test specimens. Then a total of 13 FE models were analyzed with various parameters including fiber volume fractions of HFRC, bolt diameter and thickness of steel flange. Finally, the empirical equations considering the contribution of polypropylene fiber (PF) and steel fiber (SF) obtained from the regression of the test results and FE analysis were recommended to evaluate the load-slip curve and ultimate capacity of the large high strength bolt shear connector embedded in HFRC/NC.

• 한국강구조학회 논문집
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• 제12권1호통권44호
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• pp.75-82
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• 2000

현재 접합부에 대한 연구가 활발하게 이루어지고 있다. 구조물의 설계에서는 접합부를 강접합 또는 핀접합으로 가정하여 설계를 하고 있으나, 실제 접합부의 거동은 완전한 강접합도 핀접합도 아닌 반강접의 특성을 보이고 있다. 본 연구에서는 이러한 반강접의 분야 중 더블앵글에 의한 접합부의 거동을 파악하고자 한다. 중 저층 건물에서 가새의 지지능력을 상실하거나, 갑작스럽게 발생할지 모르는 축방향 인장력에 대한 더블앵글의 거동을 상용유한요소해석 프로그램인 ABAQUS를 이용하여 3D 비선형 해석을 수행하였다. 3D 해석결과를 이용하여 더블앵글 접합부를 단순화한 앵글모델로 유도한 후 앵글의 코너에서의 회전강성을 찾아내어 더블앵글 접합부에 대한 설계 기초자료로 제시하였다.

• International Journal of Aeronautical and Space Sciences
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• 제13권4호
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• pp.446-457
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• 2012

Aeroelastic analysis of an aircraft with a high aspect ratio wing for medium altitude and long endurance capability was attempted in this paper. In order to achieve such an objective, various structural models were adopted. The traditional approach has been based on a one-dimensional Euler-Bernoulli beam model. The structural analysis results of the present beam model were compared with those by the three-dimensional NASTRAN finite element model. In it, a taper ratio of 0.5 was applied; it was comprised of 21 ribs and 3 spars, and included two control surfaces. The relevant unsteady aerodynamic forces were obtained by using ZAERO, which is based on the doublet lattice method that considers flow compressibility. To obtain the unsteady aerodynamic force, the structural mode shapes and natural frequencies were transferred to ZAERO. Two types of unsteady aerodynamic forces were considered. The first was the unsteady aerodynamic forces which were based on the one-dimensional beam shape; the other was based on the three-dimensional FEM model shape. These two types of aerodynamic forces were compared, and applied to the foregoing flutter analysis. The ultimate goal of the present research is to analyze the possible interaction between the rigid-body degrees of freedom and the aeroelastic modes. This will be achieved after the development of a reliable nonlinear beam formulation that would validate the current results as well as enable a thorough investigation of the nonlinearity. Moreover, such analysis will allow for an examination of the above-mentioned interaction between the flight dynamics and aeroelastic modes with the inclusion of the rigid body degrees of freedom.

• Journal of Magnetics
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• 제18권3호
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• pp.297-301
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• 2013

Flux-reversal machine (FRM) is cost effective and suitable for mass production due to its simple structure. However, there is a notable permanent magnet flux leakage which deteriorates the performance. To compensate this drawback with a design method, an Inset-Permanent-Magnet-Type FRM (ITFRM) has been proposed. The ITFRM has permanent magnets perpendicular to the stator teeth surface, and thus, is much more difficult to demagnetize. In this paper, we deal with the iron losses and irreversible permanent magnet demagnetization characteristics of the ITFRM according to various design variables and driving conditions. To analyze the characteristics, a two-dimensional finite-element method (2D-FEM) considering nonlinear analysis of permanent magnets is used. As a result, we propose the design variables that have the largest effects on the iron losses and irreversible magnet demagnetization.

• Geomechanics and Engineering
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• 제28권1호
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• pp.11-23
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• 2022

The response of pile foundations under lateral loads are usually analyzed using beam-on-nonlinear-Winkler-foundation (BNWF) model framework employing various forms of empirically derived p-y curves and p-multipliers. In practice, the p-y curve presented by the American Petroleum Institute (API) is most often utilized for piles in granular soils, although its shortcomings are recognized. The objective of this study is to evaluate the performance of the BNWF model and to quantify the error in the estimated pile response compared to a rigorous numerical model. BNWF analyses are performed using three sets of p-y curves to evaluate reliability of the procedure. The BNWF model outputs are compared with results of 3D nonlinear finite element (FE) analysis, which are validated via field load test measurements. The BNWF model using API p-y curve produces higher load-displacement curve and peak bending moment compared with the results of the FE model, because empirical p-y curve overestimates the stiffness and underestimates ultimate resistance up to a depth equivalent to four times the pile diameter. The BNWF model overestimates the peak bending moment by approximately 20-30% using both the API and Reese curves. The p-multipliers are revealed to be sensitive on the p-y curve used as input. These results highlight a need to develop updated p-y curves and p-multipliers for improved prediction of the pile response under lateral loading.

• 한국항공우주학회지
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• 제31권4호
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• pp.44-52
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• 2003

형상기억합금은 스마트 구조물에서 작동기로 널리 쓰인다. 형상기억합금은 초기변위를 부고 열을 가하게 되면 단위 부피당 큰 회복력과 변위를 발생한다. 형상기억합금의 이론 특성은 인공근육, 작동기, 소음 및 진동감쇠, 형상의 변형 제어 등에 응용될 수 있다. 본 논문에서는 형상기억합금의 3차원 비선형 구성방정식을 이용하여 재료의 거동특성을 해석하고, 형상기억합금이 부착된 스마트구조로 응용될 수 있는 공기 흡입 덕트, 항공기 및 잠수함 동체 등의 구조를 압력이 존재하는 원형 및 복원을 해석하였다. 수치해석결과, 형상기억합금 엑츄에이터가 내압 하에서 작동하자 단면은 변형전의 모습(낮은 응력상태)으로 회복되었다.

• 한국전산구조공학회논문집
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• 제24권3호
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• pp.343-351
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• 2011

원자로 격납건물은 원자력발전소에서 발생가능한 모든 비상사태에 대한 최후의 방벽 역할을 하고 있다. 따라서 사고발생시 원자로 격납건물의 극한능력을 판단하는 것은 매우 중요하다. 대표적인 고려사항 가운데 하나인 LOCA사고 발생시 CANDU형 원자로 격납건물의 극한능력을 파악하기 위해서는 구조적 안전성 평가를 위한 구조해석이 필요하다. CANDU형 원자로 격납건물은 돔과 원통형벽체로 구성된 프리스트레스 콘크리트 쉘 구조물로서 부착식 텐돈을 사용하고 있다. 본 논문에서는 극한내압능력의 평가를 위하여 3차원 구조해석시스템을 사용한 프리스트레스 콘크리트 격납건물의 비선형해석을 수행하였다.