Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main facto...Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main factors that affect the cladding performance during normal or off-normal operation, which induces force interaction between the pellet and cladding. In the case of a normal operation period, to estimate the cladding stress and strain, various models and codes have been developed using a simplified 1D （one-dimensional） assumption. However, in the case of a slow ramp during start-up and shut-down and a fast transient such as an AOO （anticipated operational occurrence）, it is difficult for a 1D model to simulate the cladding stress and strain accurately due to its modeling limitation. To model a large deformation along the radial and axial directions such as a ＂＇ballooning＂ phenomenon, FE （finite element） modeling, which can simulate a higher degree of freedom, is an indispensable requirement. In this work, an axisymmetric two-dimensional FE module, which will be integrated into the transient fuel performance code, has been developed. To solve the mechanical equilibrium of the pellet-cladding system, taking into account the geometrical and material non-linearities, the FE module employs an ESF （effective-stress-function） algorithm. Verifications of the FE module for the cases of thermal and elastic analyes were performed using the results of ANSYS 13.0.展开更多
This paper presents the characteristics of the crack growth at the interface of rubber-rubber and rubber-steel bimaterials undertensile deformation using the non-linear finite element method. By using the commercial f...This paper presents the characteristics of the crack growth at the interface of rubber-rubber and rubber-steel bimaterials undertensile deformation using the non-linear finite element method. By using the commercial finite element software ABAQUS,the J integral calculations are carried out for the initial interface crack in the interfaces in-between two Neo-Hookean materials,two Mooney-Rivlin materials, Neo-Hookean and Mooney-Rivlin rubbers, Neo-Hookean and Polynomial, Mooney-Rivlin andPolynomial, and the Mooney-Rivlin and steel bi-materials. The computational results of the maximum J integral directionaround the crack tip illustrate the possible direction of crack growth initiation. Furthermore, it is found that the crack bends tothe softer rubber material at a certain angle with the initial crack direction if the crack depth is relatively small. For the crackwith a larger depth, the crack propagates to grow along the interface in-between the bimaterials.展开更多
文摘Because zirconium alloy cladding is the first containment barrier for fission products, its mechanical integrity is the most important concern. In view of the mechanical integrity, stress and strain are the main factors that affect the cladding performance during normal or off-normal operation, which induces force interaction between the pellet and cladding. In the case of a normal operation period, to estimate the cladding stress and strain, various models and codes have been developed using a simplified 1D （one-dimensional） assumption. However, in the case of a slow ramp during start-up and shut-down and a fast transient such as an AOO （anticipated operational occurrence）, it is difficult for a 1D model to simulate the cladding stress and strain accurately due to its modeling limitation. To model a large deformation along the radial and axial directions such as a ＂＇ballooning＂ phenomenon, FE （finite element） modeling, which can simulate a higher degree of freedom, is an indispensable requirement. In this work, an axisymmetric two-dimensional FE module, which will be integrated into the transient fuel performance code, has been developed. To solve the mechanical equilibrium of the pellet-cladding system, taking into account the geometrical and material non-linearities, the FE module employs an ESF （effective-stress-function） algorithm. Verifications of the FE module for the cases of thermal and elastic analyes were performed using the results of ANSYS 13.0.
基金supported by the Hong Kong Polytechnic University (Grant No. G-YH32)
文摘This paper presents the characteristics of the crack growth at the interface of rubber-rubber and rubber-steel bimaterials undertensile deformation using the non-linear finite element method. By using the commercial finite element software ABAQUS,the J integral calculations are carried out for the initial interface crack in the interfaces in-between two Neo-Hookean materials,two Mooney-Rivlin materials, Neo-Hookean and Mooney-Rivlin rubbers, Neo-Hookean and Polynomial, Mooney-Rivlin andPolynomial, and the Mooney-Rivlin and steel bi-materials. The computational results of the maximum J integral directionaround the crack tip illustrate the possible direction of crack growth initiation. Furthermore, it is found that the crack bends tothe softer rubber material at a certain angle with the initial crack direction if the crack depth is relatively small. For the crackwith a larger depth, the crack propagates to grow along the interface in-between the bimaterials.
