http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Hot-Air Forming of Al-Mg-Cr Alloy and Prediction of Failure Based on Zener-Holloman Parameter
김우진,W. Y. Kim,H. K. Kim 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.6
The microstructure of an Al-Mg-Cr alloy tube fabricated through indirect extrusion at 673 K showed elongated grains with a mean size of ~26 μm. The strain rate-stress relationship at high temperatures (753 K to 793K) revealed that dislocation climb creep was the rate-controlling deformation mechanism. The hot-air forming process was successful at a pressure of 70 bar. The Zener-Hollomon parameter based failure criterion was 3602+, and was used to explain the failure behavior of a deforming body. The forming and fracture behavior of the Al-Mg-Cr alloy tube was analyzed with the aid of finite element (FE) simulation, into which the failure criterion was incorporated. Comparison of the simulation and the experimental results indicated that the proposed fracture criterion was useful in predicting the fracture behavior of aluminum tube deforming by means of gas pressure.
AZ31판재 온간 성형의 파단 예측을 위한 한계응력 모델
김흥규(H. K. Kim),김우진(W. J. Kim) 한국소성가공학회 2010 한국소성가공학회 학술대회 논문집 Vol.2010 No.5
Magnesium alloy sheet has a relatively low formability compared to other commercial structural metals though it is press-formed at elevated temperatures to improve the press formability. In general, the formability of magnesium alloy sheet is known to depend on temperature as well as strain-rate imposed on the material, and the accurate prediction of the formability considering the dependence is crucial to design the forming process of magnesium alloy sheet parts. In the recent work, we proposed the failure models based on the critical damage work as well as the critical strain for warm forming of AZ31 sheet. However, it is to be examined whether the criterion is capable of predicting the forming limits for various strain paths of sheet metal before applying the failure model to the sheet forming process under complex strain modes. In this paper, we propose a simple stress-based failure criterion for warm forming of AZ3l sheet motivated by the stress-based FLD concept suggested by Stoughton (2000). The predictability of the stress-based failure criterion will be examined compared with the previous damage work- or strain-based failure models.
풍력 블레이드 복합재의 결함 탐상을 위한 NDE 모니터링기법
임광희(K. H. Im),김우진(W. J. Kim),정예원(Y. W. Jeong),조철현(C. H. Cho),김선규(S. K. Kim),조영태(Y. T. Cho) Korean Society for Precision Engineering 2021 한국정밀공학회 학술발표대회 논문집 Vol.2021 No.11월
Terahertz waves (T-ray) was extensively studied for the nondestructive evaluation of characterization of various and FRP composite materials for a use of wind energy. The composite materials are being utilized on the various areas. Here, T-rays were used to perform NDE when detecting defects in the trailing edge of a wind turbine blade. This study proposed a method to measure a refractive index of a composite, using T-rays (THz) and reviewed the characteristics of the T-ray E-field of a CFRP composite. Particularly, this study produced images to determine defects in the trailing edge of a wind turbine blade and compared and analyzed the images. The TOF of T-ray penetration was measured using a T-ray through-transmission mode to find the following characteristics of the blade. The trailing edge of a nonconductive wind turbine blade could transmit T-rays, enabling the measurement of refractive indices in a through-transmission mode. The effectiveness and limitations of T-ray for the NDE of composites are discussed.
초음파 비파괴 검사 기반의 용접결함 패턴분류기 성능 비교
김재열(J. Y. Kim),김창현(C. H. Kim),김우진(W. G. Kim),최철준(C. J. Choi),윤성운(S. U. Yoon) 한국생산제조학회 2005 한국공작기계학회 추계학술대회논문집 Vol.2005 No.-
In this study, we compared backpropagation neural network(BPNN) with probabilistic neural network(PNN) as shape recognition algorithm of welding flaws. For this purpose, variables are applied the same to two algorithm. Here, feature variable is composed of time domain signal itself and frequency domain signal itself. Through this process, we comfirmed advantages/disadvantages of two algorithms and identified application methods of two algorithms.