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티타늄 합금의 연마제 워터 제트 절단에 의한 절단표면 특성
정남용,진윤호,Chung Nam-Yong,Jin Yun-Ho 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.1
Abrasive waterjet (AWJ) can provide a more effective means for precision of difficult -to-machining materials such as ceramics and titanium alloys. The present study is focused on the surface roughness of abrasive waterjet cut surfaces. This paper investigated theoretical and experimental surface characteristics associated with abrasive waterjet cutting of titanium alloy Gr2. It is shown that the proper variations of several cutting parameters such as waterjet cutting pressure, cutting speed and cutting depth improve the roughness and characteristics on specimen surfaces produced by AWJ cutting. From the experimental results by AWJ cutting of titanium alloy Gr2, the optimal cutting conditions to improve the surface roughness and precision were proposed and discussed.
반도체 패키지의 층간박리 파괴역학인자 해석 및 균열진전경로 예측
정남용,박철희,Chung, Nam-Yong,Park, Cheol-Hee 한국생산제조학회 2009 한국생산제조학회지 Vol.26 No.3
This paper presents a method of calculating the stress intensity factor (K) and crack propagation direction (${\theta}_0$) at the crack-tip that is associated with delamination in the large scale integration(LSI) package. To establish a reasonable strength evaluation method and life prediction, it is necessary to assess fracture parameters under various fracture conditions. Therefore, we conducted quantitative stress singularity analysis considering thermal stress simulating the changes of crack length (a), (h) and (v) in delamination using the 2-dimensional elastic boundary element method (BEM), and from these results predicted crack propagation direction and path.
정남용,박철희,Chung, Nam-Yong,Park, Cheol-Hee 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.4
In this paper, an evaluation method of fracture toughness on interface cracks was investigated in friction welded dissimilar materials with interfacial edge cracks. To establish a reasonable strength evaluation method and fracture criterion, it is necessary to analyze stress intensity factor under the load and residual stress condition on friction welded interface between dissimilar materials. The friction welded specimens with an edged crack were prepared for analysis of stress intensity by using the boundary element method (BEM) and the fracture toughness. A quantitative fracture criterion for friction welded STS 304/SM 45C with interface crack is suggested by using stress intensity factor, F and the results of fracture toughness experiment.
Al/ Epoxy 이종 접합체에 대한 계면강도의 평가방법
정남용,Chung, Nam-Yong 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.11
The application of bonded dissimilar materials to industries as automobiles, aircraft, rolling stocks, electronic devices and engineering structures is increasing gradually because these materials, compared to the homogeneous materials, have many advantages for material properties. In spite of such wide applications of bonded dissimilar materials, the evaluation method of quantitative strength considering the stress singularities for its bonded interface has not been established clearly. In this paper, the stress singularity for Bctors and the stress intensity factors were analyzed by boundary element method(BEM) for the scarf joints of Al/Epoxy with and without a crack, respectively. From static fracture experiments of the bonded scarf joints, a fracture criterion and a evaluation method of interface strength in bonded dissimilar materials were proposed and discussed.
정남용(N.Y.Chung),이원(W.Yi),정의섭(E.S.Jeong) 한국자동차공학회 1994 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, the widespread use of dissimilar materials in metal/ceramics, resin/metal, IC package, coating, brazing and soldering which is required bonded strength evaluation at the interface edge of bonded joint in dissimilar materials.<br/> In this paper, the stress distribution and stress singularity of single-lap joint in dissimilar materials were investigated analytically by the bogy's solution and numerically by using boundary element method, The numerically calculated results of the stress singularity by boundary element method were in good agreement with Bogy's analytical solution. On the basis of the obtained results, the effects of dissimilar materials combinations. bonded length and fillet angle at the interface edge are discussed.
SUH35/SUH3 마찰용접 접합계면에 대한 잔류응력 특이성의 해석
정남용(Nam yong Chung),박철희(Chul Hee Park),이대영(Dae young Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_2
With increasing use of SUH35/SUH3 dissimilar materials for automotive engine valve, it is required that stress singularities on an interface for friction welded dissimilar materials analyzed to establish strength evaluation. The stress singularity index(λ) and stress singularities factor(Γ) were calculated from using the results of stress analysis to consider residual stress and loads. The stress singularities on variations for shapes and thickness of welded flashes were analyzed and discussed. This paper suggested that the strength evaluation by using the stress singularity factors as fracture parameters, considering the stress singularity on an interface edge of friction welded dissimilar materials will be useful.
접착부재의 초음파 감쇠계수에 의한 계면균열 길이의 측정
정남용(Namyong Chung),박성일(Sungil Park) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, the ultrasonic attenuation coefficient was measured by interfacial crack lengt in the adhesive components of double-cantilever beam(DCB). The energy release rate, G, was obtained by the experimental measurement of compliance. The numerical analysis by the boundary element method(BEM) and Ripling's equation were investigated. The experimental results represents that the relation between interfacial crack length for the ultrasonic attenuatio<br/> coefficient and energy release rate is increased proportionally. From the experimental results, a measurement method of interfacial crack length by the ultrasonic attenuation coefficient was proposed and discussed.<br/>