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안상태,강국정,홍석균,Ahn, Sang-Tae,Kang, Kuk-Jung,Hong, Suk-Kyun 한국군사과학기술학회 2010 한국군사과학기술학회지 Vol.13 No.3
The necessity for harmonically growing of economy and environment has been on the rise late in the twentieth century. Green transformation is defined as efficiency enhancement of conventional guns and ammunitions. We also define green innovation as evolution of fire power systems breaking with conventional methodology. This kind of green innovation could even change a paradigm of warfare in the future. In this paper, we classify the green technology in the field of fire power into five technological groups, and the research and development trend of green technology in the field of fire power is analyzed.
〈응용논문〉 : 내부압력 작용하에서 자긴가공 실린더 구조의 응력거동
김학인(Hakin Gimm),강국정(Kuk Jung Kang),안상태(Sang Tae Ahn),홍석균(Suk Kyun Hong) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
압력용기와 실린더 형태의 구조설계 문제에 관한 이론과 실험적 연구는 매우 고전적인 문제임에도 여전히 연구 대상이다. 특히 군사용 포신 설계에서 자긴 가공으로 불리는 포열 두께 상에 과도변형 부여에 의한 압축 잔류응력 상태를 형성하여 포신의 허용 압력 증대와 이로 인한 피로수명을 높이는 기술은 새로운 포신 설계기술과 소재 발전에도 여전히 유효하다. 본 연구에서는 중공 장축 실린더 구조에 대해 자긴 이론에 관한 고찰과 이에 따른 수치해석을 통해 내부 압력이 작용된 실린더의 응력거동에 대해 살펴보았다. Although the efforts on theories and experimental works regarding the pressure vessels and gun tubes in cylinder are old aged issues, the subjects still remain the serviceable works to be continued in these days. Particularly the auttofrettage and overstraining for the gun tube in military use are still valid measures, even the advance in the technologies of gun and metallurgy, in order to enhance the operational performance with the improvement in fatigue life. Current work investigates the stress behaviors on the autofrettaged hollow cylinder which is subjected to an internal pressure loading, using the numerical methods as well as the review of theories
박재현(Jae-Hyun Park),이영신(Young-Shin Lee),김재훈(Jae-Hoon Kim),차기업(Ki-Up Cha),홍석균(Suk-Kyun Hong) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
Autofrettage process is used for internal forming and sizing of cylinder designed to withstand high internal pressures. The multi-layered cylinders can be manufactured with combining autofrettaging and shrink fit process to extend fatigue lifetimes. This paper presents an analytical analysis of compound cylinder using Tresca yield theory. The compound cylinder is investigated on principal stress and residual stress distribution. Consequently, shrink fitting is affect to stress distribution a little but residual stress distribution largely. The effects of autofrettage overstrain on the principal stress and residual stress are also studied.
심우성(Woo-Sung Shim),김재훈(Jae-Hoon Kim),이영신(Young-Shin Lee),차기업(Ki-Up Cha),홍석균(Suk-Kyun Hong) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The uniaxial tension-compression tests were conducted to evaluate Bauschinger effect in gun barrel high strength steel. The Bauschinger effect is originally defined as the phenomenon which plastic deformation causes a loss of yield strength restraining in the opposite direction. The Bauschinger effect factor(BEF), defined as the ratio of the yield stress on reverse loading to the initial yield stress, is a measure of the magnitude of the Bauschinger effect. As this factor is utilized to calculate the accurate residual stress in thick-walled cylinder after autofrettage process, evaluation of this factor is very important. The aim of the present paper is to evaluate the influence of plastic deformation and the behavior of the Bauschinger effect. From the experimental results, BEF is found to be a strong function of prior plastic strain.
이세훈(Se-Hoon Lee),이영신(Young-Shin Lee),최영진(Young-Jin Choi),채제욱(Je-Wook Chae),최의중(Eui-Jung Choe),홍석균(Suk-Kyun Hong) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
The rifle impact of human body is affected by the posture of human for rifling. The human model of shooting posture is defined by the action of shooter. The shooting impact of the rifle is transferred to the human model. In this study a finite element analysis has been performed in order to investigate the human body impact by shooting of rifle. The model(height 170 ㎝, weight 60 ㎏) is developed by finite element method using beam elements. The human body impulse is analyzed by the ANSYS 8.1 code. The human impact analysis of stand shooting posture, knee shooting posture and prone shooting posture is investigated. In this study, the rifle used for the impulse analysis is K2. The applied load for the simulation inputs is about 4 kN. As the results, the displacement and stress of human body is presented.
멱함수 가공경화 모델을 이용한 복합실린더의 자긴가공해석
박재현(Jae-Hyun Park),이영신(Young-Shin Lee),심우성(Woo-Sung Shim),김재훈(Jae-Hoon Kim),차기업(Ki-Up Cha),홍석균(Suk-Kyun Hong) 대한기계학회 2008 大韓機械學會論文集A Vol.32 No.6
In order to achieve long fatigue lifetimes for cyclically pressurized thick cylinders, multi-layered compound cylinder has been proposed. Such compound cylinder involves a shrink-fit procedure incorporating a monobloc tube which has previously undergone autofrettage. The basic autofrettage theory assumes elastic-perfectly plastic behaviour. Because of the Bauschinger effect and strain-hardening, most materials do not display elastic-perfectly plastic properties and consequently various autofrettage models are based on different simplified material strain-hardening models, which is assumed that combination of linear strain-hardenig and power strain-hardening model. This approach gives a more accurate prediction than the elastic-perfectly plastic model and is suitable for different strain-hardening materials. In this paper, a general autofrettage model that incorporates the material strain-hardening relationship and the Bauschinger effect, based upon the actual tensile-compressive stress-strain curve of a material was proposed. The model was obtained using the von Mises yield criterion and plane strain condition. The tensile-compressive stress-strain curve was obtained by experiment. The parameters needed in the model were determined by fitting the actual tensile-compressive curve of the material. Finally, strain- hardening model was compared with elastic-perfectly plastic model.
멱함수 가공경화 모델을 이용한 복합실린더의 자긴가공해석
박재현(Jae-Hyun Park),이영신(Young-Shin Lee),심우성(Woo-Sung Shim),김재훈(Jae-Hoon Kim),차기업(Ki-Up Cha),홍석균(Suk-Kyun Hong) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
In order to achieve long fatigue lifetimes for cyclically pressurized thick cylinders a multi-layer design has been proposed. Such compound cylinder involves a shrink-fit procedure incorporating a monobloc tube which has previously undergone autofrettage. The basic autofrettage theory assumes elastic-perfectly plastic behaviour. Because of the Bauschinger effect and strain-hardening, most materials do not display elastic-perfectly plastic properties and consequently various autofrettage models are based on different simplified material strain-hardening models, which is assumed that combination of linear strain-hardenig and power strain-hardening model. This approach gives a more accurate prediction than the elastic-perfectly plastic model and is suitable for different strain-hardening materials. In this paper, a general autofrettage model that incorporates the material strain-hardening relationship and the Bauschinger effect, based upon the actual tensile-compressive stress-strain curve of a material is proposed. The model is obtained using the Von Mises yield criterion and plane strain condition. The tensile-compressive stress-strain curve is obtained by experiment. The parameters needed in the model are determined by fitting the actual tensile-compressive curve of the material. Finally, strainhardening model is compared with elastic-perfectly plastic model.
이은엽(Eun-Yup Lee),이영신(Young-Shin Lee),양추명(Qui-Ming Yang),김재훈(Jae-Hoon Kim),차기업(Ki-Up Cha),홍석균(Suk-Kyun Hong) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.4
Thick-walled cylinder with high pressure have had wide application in the armament industry. In the thick-walled cylinder, fatigue crack is generated at inner radius and developed toward the outer radius. To prevent generation of fatigue crack, the autofrettage process had been used. The compressive residual stress induced by the autofrettage process extends loading pressure and fatigue life of the thick-walled cylinder. In this study, the residual stress of single and compound cylinder by the autofrettage process was evaluated. The analytical compressive residual stress of single cylinder was good agreement with experimental result at inner radius. The analysis on the residual stress of compound cylinder was conducted. The compressive residual stress at inner radius was increased with the overstrain level. And fatigue life of the compound cylinder with initial crack was evaluated. The considered initial crack shape was straight and semi-elliptical. The fatigue life was extended with the overstrain level. The fatigue life of the compound cylinder with semi-elliptical crack was longer than straight crack. The suitable way to extend fatigue life of the compound cylinder was proposed.