| Based on the stress-modified critical strain fracture criterion, a new analytic model of ductile fracture of a blunt notched specimen is proposed. With the aid of a notch tip stress and strain field in power-law hardening material given by Bates et al., the interrelatonship between the local stress and strain state and the microstructural characteristic distance is analyzed in terms of the notch root radius. From this model, the K_(IC)(ρ) values are predicted to increase with increasing ρ, but a minimum point of K_(IC)(ρ) exists at a small ρ value. Also, the material parameters which control the ductile fracture criterion, namely the microstructural characteristic distance and the reference critical strain, can be quantitatively estimated by fitting the K_(IC)(ρ) vs. ρ data on the model equation. These parameters enable us to understand more ststematically the micromechanism of ductile fracture. |
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