EXPERIMENTAL AND COMPUTATIONAL EVALUATION OF CRACK-GROWTH THROUGH A SPATIALLY NONUNIFORM MICROSTRUCTURE

Crack growth through a spatially non-uniform microstructure of 1045 st eel edge-notched and pre-cracked panel specimens was investigated expe rimentally and computationally. The microstructural gradient was produ ced by heat treatment and differential quenching. A fractographic exam ination was performed on the crack growth specimens to correlate fract ure mode and local toughness. Tensile specimens, corresponding to diff erent sites in the edge-notched panel, were used to characterize the c onstitutive response and fracture resistance of the as-treated materia l. The Rockwell B hardness was used to identify and map material const itutive responses to corresponding locations in a finite element model of the panel. A debonding algorithm was used in the finite element si mulations to model stable crack growth using a local fracture criterio n.