Dislocation-free zone model of mode III fracture: the effect of crack bluntness

✍ Scribed by Sham-Tsong Shiue; Sanboh Lee

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 306 KB
• Volume: 176
• Category: Article
• ISSN: 0921-5093
• DOI: 10.1016/0921-5093(94)90966-0

✦ Synopsis

The effect of crack blunting on mode III fracture is investigated using a discrete dislocation approach. The blunt crack is simulated by a small sharp crack emanating from a semi-elliptic hole. It is found that the applied stress intensity factor for dislocation emission increases with the number of emitted dislocations, but decreases with the increasing extent of bluntness. For a given number of emitted dislocations, the region between the crack tip and furthest dislocation increases with the bluntness of crack. However, the distance between the first dislocation and the crack tip becomes larger as the crack is more blunt. It is implied that the plastic zone and dislocation-free zone sizes increase with the bluntness of the crack. In addition, the dislocation-free zone size also increases with decreasing friction stress. The ductile vs. brittle behavior of the material is also studied. A material with a blunt crack has a lower applied stress intensity factor for dislocation emission, so it behaves more ductile.