Condition for stable growth of branched cracks

✍ Scribed by Nakasa Keijiro; Takei Hideo; Takemoto Shinji

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 534 KB
• Volume: 18
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(83)90132-7

✦ Synopsis

ln order to clarify the reason why the stable growth of branched cracks occurs in delayed failure, while not in other subcritical crack propagation process such as fatigue, the stress intensity factor after crack branching in delayed failure was dropped to various values, and the propagation behavior of both cracks was investigated.

The well balanced growth of branched cracks in delayed failure occurs only when the crack propagation velocity after crack branching belongs to the region II where the crack propagation velocity is constant independently of K. The fatigue cracks at the tips of artificially branched cracks, on the other hand, can not propagate stably, and only either crack propagates preferentially.

The exponent m in the crack propagation law (daldt = c,K" or da/dN = c!(AK)~) expresses the degree of unbalance growth of branched cracks. The stable growth of branched cracks occurs only when the crack propagation velocity is constant independently of K or AK, i.e. m = 0.