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PCVN 시편 파괴인성의 균열 깊이 영향에 대한 Scaling 모델 해석
박상윤(Sang Yun Park),이호진(Ho Jin Lee),이봉상(Bong Sang Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.4
Standard procedures for a fracture toughness testing require very severe restrictions for the specimen geometry to eliminate a size effect on the measured properties. Therefore, the used standard fracture toughness data results in the integrity assessment being irrationally conservative. However, a realistic fracture in general structures, such as in nuclear power plants, may develop under the low constraint condition of a large scale yielding with a shallow surface crack. In this paper, cleavage fracture toughness tests have been made on side-grooved PCVN (precracked charpy V-notch) type specimens (10 by 10 by 55 ㎜) with various crack depths. The constraint effects on the crack depth ratios were evaluated quantitatively by the developed scaling method using the 3-D finite element method. After the fracture toughness correction from scaling model, the statistical size effects were also corrected according to the standard ASTM E 1921 procedure. The results were evaluated through a comparison with the T0 of the standard CT specimen. The corrected T0 for all of the PCVN specimens showed a good agreement to within 5.4℃ regardless of the crack depth, while the averaged PCVN T0 was 13.4℃ higher than the real CT test results.
추진축계 비틀림 진동 감쇠를 위한 점성 댐퍼의 최적 설계
박상윤(Sang-Yun Park),한국현(Kuk Hyun Han),박주민(Ju-Min Park),권성훈(Sung Hun Kwon),송오섭(Ohseop Song) 한국소음진동공학회 2015 한국소음진동공학회 논문집 Vol.25 No.9
In this study, the torsional vibration analysis for a marine propulsion system is carried out by using the transfer matrix method(TMM). The torsional moment produced by gas pressure and reciprocating inertia force may yield severe torsional vibration problem in the shaft system which results in a damage of engine system. There are several ways to control the torsional vibration problem at hand, firstly natural frequencies can be changed by adjusting shaft dimensions and/or inertia quantities, secondly firing order and crank arrangement are modified to reduce excitation force, and finally lower the vibration energy by adopting torsional vibration damper. In this paper, the viscous torsional vibration damper is used for reducing the torsional vibration stresses of shaft system and it is conformed that optimum model of the viscous damper can be determined by selecting the geometric design parameters of damper and silicon oil viscosity.
경계조건에 따른 자기장 및 열하중을 받는 복합재료 원통셸의 진동해석
박상윤(Sang-Yun Park),김성균(Sung-Kyun Kim),최종운(Jong-Woon Choi),송오섭(Ohseop Song) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.10
In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT with two different boundary conditions(C-C, S-S) was performed through discretization of equations of motion and boundary condition. Model of laminated composite cylindrical shells subjected to a combination of magnetic and thermal fields is developed via Hamilton’s variational principle. These coupled equations of motion are based on the electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Variations of dynamic characteristics of composite shells with applied magnetic field, temperature gradient, and stacking sequence for each boundary conditions are investigated and pertinent conclusions are derived.
박상윤(Sang-Yun Park),김성균(Sung-Kyun Kim),최종운(Jong-Woon Choi),송오섭(Ohseop Song) 한국소음진동공학회 2012 한국소음진동공학회 학술대회논문집 Vol.2012 No.4
In this paper free vibration analysis of symmetric and cross-ply elastic laminated shells based on FSDT was performed through discretization of equations of motion and boundary condition. Model of laminated composite shells subjected to a combination of magnetic and thermal fields is developed. These coupled equations of motion are based on the electromagnetic equations (Faraday, Ampere, Ohm, and Lorenz equations) and thermal equations which are involved in constitutive equations. Dynamic characteristic of composite shells for change of magnetic fields is investigated.