engleski

Influence of chosen expression for J-integral and plastic collapse loads on structural integrity assessment of surface cracked thick-walled tubes

The plastic limit and collapse loads as well as the stress intensity factor and J-integral of thick-walled tubes with external axial semi-elliptical surface cracks are investigated by three-dimensional non-linear finite element analyses. Unlike the existing solutions, the newly developed analytical approximation of the plastic limit pressure for thick-walled tubes is applicable to a wide range of crack dimensions. The influence of the choice of flow stress on the plastic collapse estimation of steam generator tubes is considered. Numerical results show that the flow stress, defined by some Failure Assessment Diagram methods, depends not only on the tube material, but also on the crack geometry. Further, for application of the J-integral results to general stress-strain laws, the J estimation equation is re-formulated using the modified reference stress approach.

J-integral; plastic limit pressure; plastic collapse pressure; GE/EPRI; reference stress method

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