http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
계장화 압입시험에 의한 용접부의 물성 측정 및 피로수명 예측
구병춘,이동형,권동일,최열,Goo, Byeong-Choon,Lee, Dong-Hyung,Kwon, Dong-Il,Choi, Yeol 한국철도학회 2004 한국철도학회논문집 Vol.7 No.2
When material properties depend much on positions in a material or it is difficult to make test specimens from a material or component, an instrumented indentation test described in ISO 14577-1, 14577-2 or KS B 0950 can be used to measure material properties and damage. In this study, first of all, the principals of the instrumented indentation test, KS B 0950 are introduced and yield strengths, tensile strengths and work hardening exponents of base materials, heat affected zones and weld materials are measured. In addition, the influence of post-weld heat treatment on the material properties is investigated. Finally the fatigue lift of butt welded specimens are evaluated by the local strain approach. To calculate local strains and stresses, elasto-plastic finite element analysis is conducted using the measured properties.
구병춘,김재훈,Goo, Byeong-Choon,Kim, Jai-Hoon 대한용접접합학회 2007 대한용접·접합학회지 Vol.25 No.1
A lot of fatigue tests on a material, JIS SM490A, with yielding strength of about 350 MPa and tensile strength of about 520 MPa were carried out. Various butt-welded specimens such as reinforcement removed, as-welded and weld toe ground, several types of fillet-welded specimens and full-size box type components were used. After having obtained S-N curves for the above- mentioned specimens, fatigue strengths were compared to those of foreign design codes, AWS, BS 7608 and ENV. It was found the fatigue strengths at low cycles are not in a good agreement with the foreign codes, but the fatigue limits are in a good agreement.
Al6061-T6 판재의 마찰교반용접 3D 유한요소 해석
구병춘,정현승,Goo, Byeong-Choon,Jung, Hyun-Seung 대한용접접합학회 2011 대한용접·접합학회지 Vol.29 No.4
Friction stir welding (FSW) is a solid state joining method patented in 1991 by The Welding Institute (TWI). It is widely used for joining light metals such as Al and Mg alloys. Foreign railway vehicle manufacturing companies have been applying FSW to car body welding, but domestic companies are in the beginning of feasibility study. Therefore, lots of experimental and analytical study is needed. In this study, three-dimensional finite element modeling of the friction stir welding of two Al6061-T6 plates was carried out. And temperature field and residual stresses were obtained and compared to experimental results in the literature. It is found the analytic thermal field is in a good agreement with the experimental results, but there are some differences between numerical and experimental residual stresses.
구병춘(Byeongchoon Goo),김재훈(Jaehoon Kim),양승용(Sungyong Yang),서정원(Jungwon Seo),정홍채(Hungchai Jung) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
First of all, experimental study on the fatigue behavior of SM 490 A was carried out on double V-grooved butt welded plates such as reinforcement removed, as-welded and weld toe ground. In addition, welded plates with transverse fillet welded web, load carrying cruciform fillet welded plates, non-load carrying cruciform fillet welded plate and longitudinal butt welded plates were tested. The obtained S-N curves for the weld details are compared each other. To evaluate the fatigue life a simple model considering residual stress relaxation was proposed and applied. Estimated results show the developed model seems to be applicable.
계장화 압입시험에 의한 용접부의 물성 측정 및 피로수명 예측
구병춘(Byeong-Choon Goo),이동형(Dong-Hyung Lee),권동일(Dong-Il Kwon),최열(Yeol Choi) 한국철도학회 2004 철도저널 Vol.7 No.2
When material properties depend much on positions in a material or it is difficult to make test specimens from a material or component, an instrumented indentation test described in ISO 14577-1, 14577-2 or KS B 0950 can be used to measure material properties and damage. In this study, first of all, the principals of the instrumented indentation test, KS B 0950 are introduced and yield strengths, tensile strengths and work hardening exponents of base materials, heat affected zones and weld materials are measured. In addition, the influence of post-weld heat treatment on the material properties is investigated. Finally the fatigue life of butt welded specimens are evaluated by the local strain approach. To calculate local strains and stresses, elasto-plastic finite element analysis is conducted using the measured properties.
[구조강도부문] 유한요소법에 의한 드럼과 라이닝의 접촉해석
구병춘(Byeongchoon Goo),서정원(Jungwon Seo) 한국자동차공학회 2000 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In the case of axisymmetric thermal analysis of drum brakes, the distribution of frictional heat produced in the interface and temperature difference between mating frictional faces are very interesting problems to computational researchers. In the first part, heat conduction from the interface to the pad and the drum was modeled by using a thin interface element, so artificial division of the generated heat flux between pad and drum is not necessary. Temperature difference between mating frictional faces is successfully modeled by using the interface element. In the second part the influence of some parameters on the thermal distribution is checked. The analysis was performed by ABAQUS/Standard code.
구병춘(B. C. Goo),정현승(H. S. Jung) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Aluminum alloy composites with SiC particles are useful for weight reduction of mechanical components. But they are expensive and it is difficult to make complex components. If we found out a reliable method to join aluminum alloys and Al/SiC composites, we could make complex mechanical parts at a low price. In this study A356 aluminum alloy and A356/SiC 20 vol.% composite were chosen as dissimilar materials. To join two different materials by casting, first, A356 blocks were cast and cylindrical holes with conical end were drilled in the blocks. A mold with a cylindrical hole was placed on an A356 cast block. Molten A356/SiC at about 750℃ was poured into the mold. Before pouring molten A356/SiC, A356 blocks were heated and kept at 550℃. Using the specimens tensile strength tests were carried out. As tensile forces increased, some composite bars were pulled out from the A395 blocks and others fractured near the border. Tensile strengths depended on the surface conditions of the cast-bonded joints.
SM490A 용접시편의 초음파 핀 피닝 및 피로수명 평가
구병춘(Byeong-Choon Goo) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.4
용접부는 용접비드의 토우에서 균열이 발생하여 파손되는 경우가 대부분이다. 용접으로 토우 주변에는 미세조직이 변하고 표면이 거칠어져 응력집중이 발생하고 용접에 의한 인장 잔류응력이 작용하므로 구조강도 측면에서 매우 취약하다. 고주파 핀 피닝기술은 용접 토우 주위를 고주파 가진 액추에이터에서 발사된 핀으로 타격하여 소성변형을 발생시켜 표면의 인장 잔류응력을 압축 잔류응력으로 바꾸고, 조직을 미세하게 하며 응력집중을 완화하여 피로강도를 향상하는 기술이다. 본 연구에서는 용접부의 피로강도 향상에 탁월한 효과가 있는 이동형 고주파 피닝장치를 개발하고 성능을 평가하였다. MP Sonic 2020A 발진기와 압전 액추에이터를 바탕으로 피닝장치의 사양을 결정하고 설계하였다. 진동 혼의 형상을 다양하게 변경하면서 고유진동수를 유한요소법으로 해석하고 형상변화와 고유진동수의 관계를 분석한 후 최적의 형상을 선정하여 시제품을 제작하였다. SM 490A 강판으로 맞대기 용접시편과 T형 필렛 용접시편을 제작하고 피닝을 한 후 4점 굽힘 피로시험을 수행하여 피닝이 용접시편의 피로수명에 미치는 효과를 평가하였다. SM 490A 강판 용접시편의 경우 피닝은 용접시편의 피로수명을 500 % 이상 향상하였다. 이러한 결과는 기존의 문헌이나 피닝 관련 자료에서 발표되고 있는 피로수명 향상 효과와 유사한 수준이다. The microstructure near the weld toe region changes during welding, and the surface becomes rough. As a result, stress concentration occurs at the toe, and tensile residual stresses are generated on the surface layer. Ultrasonic pin peening strikes the weld toe area with a pin propelled from a high-frequency actuator. It induces plastic deformation and compressive residual stress on the surface layer. It also makes the microstructure fine and smoothens the rough surface to reduce stress concentration. This study developed a portable ultrasonic pinning device. The finite element method analyzed the natural frequency for various horns with different sizes. Butt-welded and T-shaped specimens were manufactured with SM490A steel plate to evaluate the performance of the peening device. Four-point bending fatigue tests were carried out after peening to analyze the effect of peening on the fatigue life of the welding specimen. It turned out that peening improved the fatigue life of the welded specimen by more than 500 %. The results are similar to the effects published in the literature or peening-related data.