A CRACK PATH-BASED MODEL TO ASSESS MICROSTRUCTURE INCLUSIONS RANDOMNESS

ABSTRACT:
Discussed are the two main phenomena often observed in engineering materials prior to its fracture; namely dislocation-based strain hardening and the crack governing factor to steer its direction of propagation. The study investigates the micro displacements of these two mechanisms as monitored in a soft matrix full of hard obstacles (constraints). Based on a marked similarity with an artificial intelligence method called Uphill Climbing, a cellular model is so constructed that relevant formulas of plane strain analysis are properly included. In the model, the magnitude and direction of each successive micro displacement are optimized with reference to a globally updated potential objective and a locally selected stressed spots. It is found that for a randomly uniform obstacle distribution, low values of mean obstacle density lead to a direction-independent resistance against defects′ micro displacements. As obstacle density increases, such a resistance shows a direction trend. Depending on the dislocation hardening history, the 100% full loading results in several independent segments of crack paths that may either finally meet or distantly lock apart, in which cases the fractured surfaces reflect relevant distinct zones.