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2012
Conference Paper
Titel
Enhancement of local approach models for assessment of cleavage fracture considering micromechanical aspects
Abstract
The objective of the current contribution is the derivation of a micro mechanics based local probabilistic cleavage model for the assessment of the cleavage probability of ferritic steels. The probabilistic cleavage models available in literature account for the processes on the micro structural level only in a simplified manner. By a micromechanical modelling of the cleavage initiation process the effects and the interactions of the relevant parameters can be identified more precisely. For this purpose Representative Volume Elements (RVE) of the microstructure are considered, accounting for both, the grain structure as well as the brittle particles within the grain structure. The RVE's are loaded based on the local mechanical field quantities at the cleavage origins determined numerically for a variety of deep and shallow crack specimens. Thereby, the behaviour of the brittle particles acting as cleavage initiation sites can be specified for different mechanical loadin g conditions. By this micromechanical modelling the relevant parameters for the formulation of an enhanced local probabilistic cleavage model are determined. The model defined in this study accounts for micro defect nucleation as well as for the possible instability of potentially critical micro defects and provides a tool for the integrity assessment in consideration of the local loading conditions.