Naslov
Influence of flow stress choice on the plastic collapse estimation of axially cracked steam generator tubes

Autori
Tonković, Zdenko ; Skozrit, Ivica ; Alfirević, Ivo

Izvornik
Nuclear Engineering and Design (0029-5493) 238 (2008), 7; 1762-1770

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
tube; surface crack; limit load; integrity assessment; finite element analysis

Sažetak
The influence of the choice of flow stress on the plastic collapse estimation of axially cracked steam generator tubes is considered. The plastic limit and collapse loads of thick-walled tubes with external axial semi-elliptical surface cracks are investigated by three-dimensional non-linear finite element (FE) analyses. The limit pressure solution as a function of the crack depth, length and tube geometry has been developed on the basis of extensive FE limit load analyses employing the elastic-perfectly plastic material behaviour and small strain theory. 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. Further, the plastic collapse analysis with a real strain hardening material model and a large deformation theory is performed and an analytical approximation for the estimation of the flow stress is proposed. 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. It is shown that the plastic collapse pressure results, in the case of deeper cracks obtained by using the flow stress as the average of the yield stress and the ultimate tensile strength, can become unsafe.

Izvorni jezik
Engleski

Znanstvena područja
Strojarstvo

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