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가중함수법에 의한 기계적 체결부에 존재하는 타원형 모서리균열의 혼합모드 응력확대계수
허성필,양원호,김철,Heo, Sung-Pil,Yang, Won-Ho,Kim, Cheol 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.4
Mechanical joints such as bolted or riveted joints are widely used in structural components and the reliable determination of the stress intensity factors for corner cracks in mechanical joints is needed to evaluate the safety and fatigue life. This paper analyzes the mixed-mode stress intensity factors of surface and deepest points for quarter elliptical corner cracks in mechanical joints by weight function method and the coefficients included in weight function are determined by finite element analyses for reference loadings. The extended form of the weight function method for two-dimensional mixed-mode to three-dimensional is presented and the number of terms in weight function is determined by comparing the results for the different number of terms. The amount of clearance is an important factor in evaluating the severity of elliptical corner cracks in mechanical joints and even horizontal crack normal to the applied load is under mixed-mode in the case that clearance exists.
가상균열닫힘법에 의한 기계적 체결부에 존재하는 타원호형 관통균열의 응력확대계수 계산
허성필(Sung-Pil Heo),양원호(Won-Ho Yang),김철(Cheol Kim),고명훈(Myung-Hoon Ko) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.3
It has been reported that cracks in mechanical joints usually nucleate as corner cracks at the faying surface of the joints and continuously grow as elliptical arc through cracks. In this paper mixed-mode stress intensity factors for an elliptical arc through crack in mechanical joints are obtained by three dimensional finite element analysis. The virtual crack closure technique is used to calculate stress intensity factors using nodal forces at crack tip and crack opening displacements. Stress intensity factors along elliptical crack front including two surface points are analyzed and the effects of the amount of clearance in mechanical joints on stress intensity factors are investigated.
최적화 H형 스프링이 부착된 핵연료 지지격자의 충격해석
허성필(Sung-Pil Heo),윤경호(Kyung-Hlo Yoon),송기남(Kec-Nam Song) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Spacer grid in a nuclear fuel assembly holds the fuel rods in an appropriate position and provides a flow channel between the fuel rods. The spacer grid must protect the fuel rods and should not lose its role by large plastic deformation for the lateral impact force. In developing the spacer grid, therefore, it is required to evaluate its impact characteristics accurately. The spacer grid with optimized H-shape spring is designed to minimize the fretting damage, and is the optimized model to minimize the equivalent stress by the inclusion of the fuel rod. In this study, The lateral impact analysis of a 5 x 5 type partial spacer grid with optimized H-shape spring is performed. The critical impact force and maximum impact force are determined from the dynamic finite element analysis. The analysis model and procedure arc verified by comparing the analysis results with the impact test results, and the possible ways improving the prediction of test results are proposed.
김철,양원호,허성필,정기현,Kim, Cheol,Yang, Won-Ho,Heo, Sung-Pil,Chung, Ki-Hyun 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.3
The measurement of residual stresses by the hole-drilling method has been commonly used to evaluate residual stresses in structural members. In this method, eccentricity can usually occur between the hole center and rosette gage center. In this study, the error due to the hole eccentricity is predicted using the artificial neural network. The neural network has trained training examples of stress ratio, normalized eccentricity, off-centered direction and stress error using backpropagation learning process. The prediction results of the error using the trained neural network are good agreement with FE analyzed ones.
김형규(Hyung-Kyu Kim),허성필(Sung-Pil Heo),강흥석(Heung-Seok Kang),윤경호(Kyung-Ho Yoon),송기남(Kee-Nam Song) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
Studied are the deformation shape and the traction of a thin strip structure, which is in contact with a rigid<br/> cylinder. Finite element (FE) analysis is carried out to investigate the change in shape and traction during the<br/> increase of the load using the code, ABAQUS. It is found that the traction begins with Hertzian profile as the<br/> load is applied, and is changed to have the similar shape induced by the rounded punch as the load increases.<br/> This implies that the contact shape should be carefully investigated even in the period of the load increase for<br/> correct contact analysis. The analytical solution in the case of the contact with rounded punch is also<br/> discussed with the FE result.