engleski

Influence of graphite nodularity on plastification around crack tip of ductile iron

The dependence of plastic zone magnitude around crack tip on graphite nodularity of cast iron wasconsidered in this paper. Mechanical properties of four different samples of cast iron as a function of graphite nodularity (21%, 52%, 77% and 95%) were taken from available literature. At plastic deformation, the cast iron is nonlinearly hardened in accordance with the Ramberg-Osgood equation. Those data wasfitted with non-linear Ramberg-Osgood equation, where material parameters were determined using least-squares method. Thin infinite plate with straight crack was loaded perpendicularly to the crack plane. Plastic zone magnitude around the crack tip was determined according to the Dugdale model. An isotropic and non-linear strain hardening of a plate material was assumed. The stress intensity coefficient from the cohesive stresses was calculated using Green functions. The analytical methods, assuming small plastic zone around a crack tip, were used in the analysis. The results were obtained by means of commercial software package and presented in the form of diagrams.

graphite nodularity, Ramberg-Osgood equation, strain hardening exponent, Dugdale model, plastic zone magnitude around crack tip

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