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스펙트럴요소법을 이용한 동적분포하중을 받는 구조물의 동적해석
이우식,이준근,Lee, U-Sik,Lee, Jun-Geun 대한기계학회 1996 大韓機械學會論文集A Vol.20 No.6
Finite element method(FEM) is one of the most popularly used method analyzing the dynamic behaviors of structures. But unless number of finite elements is large enough, the results from FEM some what different from exact analytical solutions, especially at high frequency range. On the other hand, as the spectral analysis method(SAM) deals directly with the governing equations of a structure, the results from this melthod cannot but be exact regardless of any frequency range. However, the SAM can be applied only to the case where a structure is subjected to the concentrated loads, despite a structure could be unddergone distributed loads more generally. In this paper, therefore, new spectral analysis algorithm is introduced through the spectral element method(SEM), so that it can be applied to anlystructures whether they are subjected to the concentrated loads or to the distributed loads. The results from this new SEM are compared with both the results from FEM and the exact analytical solutions. As expected, the results from new SEM algorithm are found to be almost identical to the exact analytical solutions while those from FEM are not agreed well with the exact analytical solutions as the mode number increases.
등가연속체 Beam-Rod 모델을 이용한 항공기 날개의 공력탄성 해석
이우식,이항,Lee, U-Sik,Lee, Hang 대한기계학회 1995 대한기계학회논문집 Vol.19 No.3
It may be inefficient to conduct the aeroelastic analysis by using full-scale conventional finite-element analyses or experiments, from the initial design phase, for an aircraft wing which can be considered as the discontinuum complex structure with composite laminated skins. In this paper, therefore more efficient aeroelastic analysis has been conducted for a box-beam typed aircraft wing by using the equivalent continuum beam-rod model which is derived from the concept of energy equivalence. Equivalent structural properties of the continuum beam-rod model are obtained from the direct comparison of the finite-element matrices of continuum beam-rod model with those of box-beam typed aircraft wing. Numerical results by the continuum beam-rod model approach are compared with those by the conventional finite-element analysis approach to show that the continuum beam-rod model proposed herein is quite satisfactory as a simplified model of aircraft wing structure for aeroelastic analyses.
이우식(W.S.Lee),권태우(T.W.kwon),조열래(Y.R.Cho),김대업(D.U.Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The application of high strength steel contribute to mass efficiency with excel lent performance. In this study light weight reduction of automotive chassis parts by application of hot rolled 590 Mpa grade dual phase steel which was newly· developed was performed. The formability in stamping was revealed on the equivalent grade by relative high work-hardening coefficient. Furthermore, according to similar contents of carbon element between mass productive steel and this developed steel, those welding and painting behavior were shown good performance. For checking the durability of the automotive parts adopted the developed steel, various test were carried out, and the result was compatible with the present mass production parts.
이우식(W.S.Lee),강동포(D.P.Kang),권태우(T.W.Kwon),김대업(D.U.Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Weldability of carbon steel was influenced on the carbon composition and welding condition. In this study, weldability was investigated by microstructure, hardness, fatigue test of heat treated carbon steel S35C, S45C and untempered steel KF40CV. Although it used to the same welding wire, the different hardness was revealed by the amount of carbon content in the specimen. As the test point came close to HAZ region from the substrate, the hardness was shown the peak value. The bigger hardness gap in HAZ region, the lower value of fatigue limit at 10? cycle in the fatigue test.