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회전익 항공기용 외활형식 착륙장치의 정ㆍ동적 분석에 관한 연구
유용석,이동명,채경덕,오택열 경희대학교 산학협력기술연구원 1996 산학협력기술연구논문집 Vol.2 No.-
It is important to make sure of design's reasonability concerning of structural vibration problems and safety with fulfilling the research and with analyzing the body structures that include the landing gear which has dynamic significant characteristics in helicopter, and to make systematical procedure which obtains engineering data to guarantee the quality of the helicopter that was developed by testing of parts, subsystems and body. In this study, Analysis of landing gear under FAR regulations was attempted, and systematical procedure for static and dynamic characteristics of the landing gear in many subsystems of the helicopter was classified.
유한요소법을 이용한 복합조직강의 경도비 변화에 따른 응력-변형거동에 관한연구
吳澤烈,張現貴 慶熙大學校 材料科學技術硏究所 1992 材料科學技術硏究論集 Vol.5 No.-
Mechanical properties of dual phase steel are affected by the microstructural factor, such as, martensite volume fraction, grain size of ferrite, hardeness ratio of ferrite-martensite, connectivity and chemical properties. In this study, the tensile test was carried out to analyze the tensile characteristic of the Ferrite-Martensite dual phase steel with the Hardeness Ratio of four kinds. The result obtained could be summarized as follow ; The calculated Stress-Strain curves for four hardeness ratios were compared with their corresponding experimental curves, and in general, good agreements were found. After tensile tests were done at various tempering temperatures, we had a result that the tensile strength at 200℃ was the largest. It was found that for a given hardeness ratio, the calculated stress-strain curve was higher than experimental curve. The more reduce the hardeness ratio, the more narrow the gaps between the experimental curve and the calculated curve. It is related with the plastic constraint factor K.
吳澤烈 慶熙大學校 1984 論文集 Vol.13 No.-
This study has been made of analysis on the influence of micro-structure which releates to impact behavior of dual-phase(D.P.) steel. Some important conclusions obtained from this study are summerized in the following 1. Martensite encapsulated islands of ferrite (MEF Microstructure) satisfied the Hall-Petch relation well. In the case of Ferrite encapsulated islands of ferrite (FEM Microstructure), it didn't satisfy the relation when Impact velocity was law. According to the increase of impact velocity, however, both materials became satisfied the Hall-Petch relation completely. 2. The more matrix grain size was minute, the more maximum load was increased. And maximum load of MEF structure was higher than FEM structure. 3. Loading time of FEM structure was longer than FEM structure, and large matrix grain size prolonged the loading time. 4. Fracture toughness increased when matrix grain size became minute and martensite came to more isolated. 5. The reason that strength of MEF structure is higher than FEM structure is due to the restraint effect of plastic deformation of MEF structure.
吳澤烈 慶熙大學校 材料科學技術硏究所 1989 材料科學技術硏究論集 Vol.2 No.-
The problem on the dynamic ductile-brittle behavior is an important factor to the design of ferrite-martensite dual phase steel. The macroscopic fracture behavior of the dynamic ductile-brittle materials is related to the microscopic fracture behavior, which is explained by the micro slip together with crack initiation and propagation. Moreover, the mechanical properties of ferrite-martensite dual phase steel are affected by the microstructural factors, such as, martensite volume fraction, grain size of ferrite, strength ratio of ferrite-martensite, connectivity and chemical components etc. Therefore, this study investigated the rule of martensite on the microscope fracture behavior, the formation of micro crack and slip, the dunamic ductile-brittle fracture behavior, and plastic restraint of martensite on the plastic deformation.
吳澤烈 慶熙大學校 材料科學技術硏究所 1988 材料科學技術硏究論集 Vol.1 No.-
Mechanical properties of dual phase steel is affected by microstructural factors. Microstructural factors are composed of martensite volume fraction, grain size, hardness ratio, connectivity and chemical composition etc. In this study, connectivity of low Mn steel specimen on which other microstructural factors were made be constant has been changed by treatment process. This ferrite - Martensite dual phase specimen had given impact bending load, thereby impact strength, impact loading time and absorbed energy etc. of specimen was investigated. Some important results in this study can be summerized as follows. 1. The more connectivity increase, the more impact strength increase. Impact strength was increased according to the increase on impact velocity. 2. Based upon the velocity to cause fracture, impact load time curve shape devided into two.
Dual phase steel의 衝擊破壞特性에 關한 硏究
吳澤烈 慶熙大學校 1982 論文集 Vol.11 No.-
In this report strength, ductility, formability, energy absorption and deformed angle of dual phage being accompanied martensite volume fraction under the dynamic Impact bending load, is present. The reciprocal relations of thess factor which are studied in connection with variation impact velocity are as follows. (1) Impact maximum load is increased linearly in proportion to Martensite volume fraction increase rate. (2) Imapat maximum load is rapidly increased until fraction on the other hand, is slowly increased after fraction. (3) Loading time is nearly decreased linearly because ferrite volume decrease rate is constant. (4) Due to ferrite volume, energy absorption is decreased in proportion to martensite volume increase rate. (5) Reformed angle condition is similar until impact velocity reach 2.71 m/sec.
적층각 변화에 따른 복합재료 회전익의 구조적 연성에 관한 연구
변창환,유용석,오택열 경희대학교 산학협력기술연구원 1997 산학협력기술연구논문집 Vol.3 No.-
This study is made allowance for using one dimensional modeling method that extracts equivalent stiffness matrix used the reduction of degree of freedom in order to sufficiently express the cross section of rotor blade and the material properties of composite. Modern helicopter rotor blade which are made from anisotropic material is very important a subject on the tailoring based on coupling tearms by changing of ply angle. In basing on this, we have searched for coupling terms by changing of ply angle of composite rotor blade and the dynamic behaviour of rotor blade for each coupling term.