In technical codes and standards the strength assessment of pressurized components and systems is usually performed by limitation of fictitious elastic stresses as well as by limitation of the fatigue level. It shall be proven that the highest stresses resp. stress ranges caused by external loading show a specific margin against the resistance of the material used (concept of stress limitation). This concept is based on the principle that in a component with inhomogeneous stress distribution plastic deformation are allowed at the locations which sustain the highest loads. If in special cases the stress categorization is unclear, the effect of plastic deformation on the mechanical behavior shall be decisive. The same holds for postulated load levels with low occurrence probability (severe accidents) for which the stress limits do not utilize fully the deformation capacity of ductile materials. For that reason solutions that are based on the “Strain Limitation Concept” (SLC) shall be developed. Strength assessment using the concept of strain limitation relies on limiting strains to a specified allowable strain value, i.e. “Limit Strain Curve” (LSC). Within this presentation the approach of the concept of strain limitation is described with a special attention for the determination of the strain limits that can be allowed. With the help of Finite Element damage calculations (Rousselier model) on notched round bars the deformation behavior of an austenitic steel is described until failure. The dependency of the local failure strain on size, stress triaxiality and stress gradients is analyzed. In order to validate the numerical investigation these results are compared with experiments.

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