Discussion on the neutral angle of macrocrack-microcrack interaction

✍ Scribed by X.-M. Wang; S. Gao; Y.-P. Shen

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 137 KB
• Volume: 54
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(95)00186-7

✦ Synopsis

MArrY researchers have been paying a lot of attention to explain why the macrocrack is shielded or antishielded by microcracking within the macrocrack tip region [1][2][3][4] during the recent decade. As already known, there exists a microcrack position at which the change from the case that microcracks amplify the macrocrack to the case that microcracks shield the macrocrack takes place, it is called the neutral position, and its polar angle is called the neutral angle for considered polar radius.

In previous works, based on the change of mode I stress intensity factor from a value greater than 1 to a value less than I, and the assumption of the remote field determined by mode I stress intensity factor, the neutral angle is calculated. We think that there are still two issues to clear up in their works: (1) the mode I stress intensity factor cannot fully characterize the state of crack tip, (2) the remote field is not always determined by mode I stress intensity factor. So we are going to study the neutral angle in the problems of microcrack-macrocrack interaction using the energy release rate, and discuss the effect of the remote load phase angle on the neutral angle in the following.

Applying Muskhelishvili's linear elastic theory [5], and simulating the macrocrack described as the semi-infinite crack and microcracks of 2 'tlnit length with dislocation arrays, we have the singular equation for macrocrack as [6]