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등이축 굽힘강도를 이용한 중고 자동차용 앞창유리의 안전성 평가
조석수,이성룡,홍성왕 한국기계기술학회 2017 한국기계기술학회지 Vol.19 No.4
Recycling is required for all disused vehicle since 2015. The resource recycling act also recommends that most disused vehicle parts have to be reused except for steering and brake parts. Since vehicle windshields should provide protection for drivers and passengers, they need high structural strength and reliability. However, the vehicle windshields themselves contain many defects arising from glass production process. Because the vehicle windshields are exposed to harsh road conditions, they are expected to experience the formation and growth of surface cracks, which can result in sudden failure. In this study, equibiaxial flexural strength tests are performed on used vehicle windshields to examine whether or not the parts can endure high impact stress due to foreign flying objects. The following conclusions can be drawn: (1) The equibiaxial flexural strength of used vehicle windshields fits the two-parameter Weibull distribution. The equibiaxial flexural strength with a 99.9% failure probability is 69MPa for used vehicle windshields. (2) The equibiaxial flexural strength with six sigma quality level and maximum principal stress at vehicle windshield under high impact load are 8.05MPa and 23MPa respectively. Therefore, Structural safety factor of used vehicle windshields is 0.35 and so we should prohibit used vehicle windshields from keeping in reuse.
조석수,주원식 동아대학교 공과대학부설 생산기술연구소 1997 生産技術硏究所硏究論文集 Vol.2 No.1
Impact loads may be expected in many of the engineering applications of composites. The suitability of composites for such applications is determined not only by the usual parameters, but its impact or energy-absorbing properties. Frequently, an attempt to improve tensile properties results in a deterioration of impact properties. Therefore, it is necessaryto have a good understanding for both safe and efficient design of structures and to develop new composites suitable to service conditions. This study presents optimization techniques on the basis of genetic algorithms to minimum stiffness design of laminated composites.
실험계획법과 유한요소법을 이용한 4기통 SOHC 엔진용 로커 암 축의 피로파손해석에 관한 연구
조석수,이성룡,문성동 三陟大學校 産業科學技術硏究所 2003 産業科學技術硏究論文集 Vol.8 No.2
Failure analysis of mechanical components is divided into naked eyes, SEM. X-ray fractography. This methods can predict applied load as well as failure type. But This cann't evaluate the boundary condition under failure condition and play an important role in structural design. Therefore, This study evaluates the most dangerous boundary condition of rocker arm shaft by DOE and FEM and the safety-of it.
균질화법과 변동벡터를 이용한 전동차 크로빔의 위상최적화에 관한 연구
조석수,이성룡,문성동 三陟大學校 産業科學技術硏究所 2004 産業科學技術硏究論文集 Vol.9 No.1
Electric vehicle body has to be subjected to uniform load and requires auxiliary equipment such as air pipe and electric wire pipe. Especially, the cross beam supports the weight of passenger and electrical equipments. This needs to use adaptive design in initial design stage to gain economy through interchangeability between many kinds of components. This study performs the topology optimization by the concept of homogenization based on optimality criteria method which is efficient for the problem with a number of boundary condition and design variable. Therefore this provides the method to determine the optimum position and the shape of circular hole in the cross beam and then can achieve the weight minimization of electric vehicle body.
인공지능형 네트워크를 이용한 재료거동모델링에 관한 연구
조석수,김민철,주원식 동아대학교 생산기술연구소 1999 生産技術硏究所硏究論文集 Vol.4 No.1
Backpropagation neural networks performs computer simulations that have the potential to find the same patterns that fatigue practitioners recognize to relate experimental results to fatigue life prediction. This potential was used to construct neural networks to recognize the relation between X-ray diffraction half-value breadth ratio B/Bo, fractal dimension D_f, stress amplitude Δσ, main crack length α, (Δσ/σ_ys)^ma^n and da/dN, N/N_f for Al 2024-T3 alloy. Learning and generalization of neural networks was optimized by floating rate method. This study shows that neural networks has ability to predict fatigue crack growth rate and life on data of unlearned experimental condition.
프랙탈 차원을 이용한 재료손상의 자기 상사성에 관한 연구
조석수,주원식 동아대학교 생산기술연구소 1999 生産技術硏究所硏究論文集 Vol.4 No.1
The postion and the length of surface micro-crack has random properties. It is difficult to detect the progressive changes in surface micro-crack distribution that occur during fatigue stressing. In this paper to overcome this problem, fractal dimension was introduced to characterized the change in two-dimensional surface micro-crack distribution during fatigue process. Box counting method was adopted to measure the fractal dimension. The features of surface micro-crack growth and coalescence have fractal property. Fractal dimension increases with the number of cyclic load. Remaining fatigue life of mechanical components can be predicted by the relation between fractal dimension and cycle ratio to fracture. Therefore, we proposed complex system design that uses fractal dimension in material design and structure design and safety estimation.
다축하중을 받는 적층복합재료의 강성 및 중량 최적설계에 관한 연구
조석수,주원식,장득열 동아대학교 공과대학부설 생산기술연구소 1997 生産技術硏究所硏究論文集 Vol.2 No.1
The present paper deals with the stiffness and weight optimization of laminated composites under multiaxial loading on the basis of genetic algorithms. Laminated composites are in the form of laminates consisting of multiple laminae oriented in the design directions and bonded together in a structural unit. Design variables used in optimization are layer angle and thickness. In order to prevent GA from premature convergence, subelitism is used instead of elitism. It is shown that GA is applicable to multivariable design as well as single varialbe design.
평면굽힘하중을 받는 Al 2024-T3 합금의 미소균열 분포특성에 관한 연구
조석수,주원식,장득열,장백선,안원기 동아대학교 공과대학부설 생산기술연구소 1997 生産技術硏究所硏究論文集 Vol.2 No.1
Machine structures, aircraft and pressure vessel etc. are designed by fail-safe or safe-fail concept but on the basis of existance of internal defect or crack initiation in early stage of fatigue life. Failure or fracture of machine structures is mainly occured by fatigue and relation between stress intensity factor range and crack growth rate can predict remaining life in components containing through-the-thickness crack but fatigue life of smooth specimen is dependent of initiation, growth and coalescene of micro-crack. Therefore, this paper presents relation between statistical properties of micro crack and fatigue life ratio in age-hardened Al 2024-T3 tested in-plane bending.